2010 Canada Basin seismic reflection and refraction survey, western Arctic Ocean

2010 Canada Basin seismic reflection and refraction survey, western Arctic Ocean
GEOLOGICAL SURVEY OF CANADA
OPEN FILE 6720
2010 Canada Basin seismic reflection and refraction
survey, western Arctic Ocean:
CCGS Louis S. St-Laurent expedition report
D.C. Mosher, J.W. Shimeld and C.B. Chapman
2011
GEOLOGICAL SURVEY OF CANADA
OPEN FILE 6720
2010 Canada Basin seismic reflection and refraction
survey, western Arctic Ocean:
CCGS Louis S. St-Laurent expedition report
D.C. Mosher, J.W. Shimeld and C.B. Chapman
2011
©Her Majesty the Queen in Right of Canada 2011
doi:10.4095/288024
This publication is available from the Geological Survey of Canada Bookstore
(http://gsc.nrcan.gc.ca/bookstore_e.php).
It can also be downloaded free of charge from GeoPub (http://geopub.nrcan.gc.ca/).
Recommended citation
Mosher, D.C., Shimeld, J.W. and Chapman, C.B., 2011. 2010 Canada Basin seismic reflection and
refraction survey, western Arctic Ocean: CCGS Louis S. St-Laurent expedition report,
Geological Survey of Canada, Open File 6720, 252 p.
Publications in this series have not been edited; they are released as submitted by the author.
ii
2010 Canada Basin Seismic Reflection and Refraction
Survey, western Arctic Ocean:
CCGS Louis S. St-Laurent expedition report
August 4 – September 15, 2010
Kugluktuk, NWT to Kugluktuk, NWT
CCGS Louis S. St-Laurent
Photo by Bill Schmoker
Captain Andrew McNeill, Commanding Officer
Dr. David C. Mosher, Chief Scientist
Mr. John W. Shimeld, Second Scientist
Mr. C. Borden Chapman, Senior Technician
iii
Executive Summary
The principal objective of the 2010 Canadian Polar Margin Seismic Reflection and
Refraction Survey was to acquire multichannel seismic reflection and refraction data
along positions that serve to establish sediment thicknesses and acquire bathymetric
soundings along Canadian and US western Arctic continental margins. Strategic ship
track lines were established to complement existing data to meet UNCLOS Extended
Continental Shelf (ECS) sediment thickness, bathymetric and scientific objectives. In
addition to the geoscience program, ice observations were acquired to groundtruth
remotely sensed data. Seismic system calibration experiments were conducted to quantify
sound signal intensity levels produced by the sound source. 3673 line-km of high quality
multichannel seismic reflection data were acquired in addition to seismic refraction data
recorded from 34 sonobuoy deployments. 9500 line-km of single beam bathymetry data
were obtained plus 61 helicopter spot soundings. In collaboration the United States Coast
Guard Cutter Healy, similar amounts of multibeam bathymetric and chirp subbottom
profiler data were acquired.
iv
CCGS LOUIS S. ST-LAURENT
AUGUST 4th - SEPTEMBER 15th, 2010
v
Table of Contents
Chapter 1: 2010 Canada Basin seismic reflection and refraction survey, western
Arctic Ocean: CCGS Louis S. St-Laurent expedition report: Summary
D.C. Mosher, J. Shimeld, C.B. Chapman …………………………… 1
Chapter 2: Acquisition and Processing of the Seismic Reflection Data
J. Shimeld ………………………….…………………………………. 49
Chapter 3: Canadian Hydrographic Service Report
J. Biggar ……………………………….......................................……. 69
Chapter 4: LSSL2010 Seismic System Calibration Experiment
D.C. Mosher ………………………….……………………………… 94
Chapter 5: Ice and Weather Conditions Summary
B. Barrette ……………………………………...................................108
Appendices ……………………………………..............................................136
Executive Summary ........................................................................................................... iv
The principal objective ...................................................................................................... iv
Table of Contents................................................................................................................ v
Table of Contents............................................................................................................... vi
Figure Captions.................................................................................................................. ix
List of Tables .................................................................................................................... xii
Chapter 1: 2010 CBSRRS Summary .............................................................................. 1
Introduction......................................................................................................................... 1
Objectives ........................................................................................................................... 1
Personnel............................................................................................................................. 2
Scientific Personnel ........................................................................................................ 2
CCGS Louis S. St-Laurent Personnel............................................................................. 2
Navigation, Record Keeping and Networking.................................................................... 5
Seismic Reflection and Refraction.................................................................................... 11
Seismic Source.............................................................................................................. 12
Compressors.................................................................................................................. 13
Geometrics GeoEel Digital Streamer............................................................................ 14
Seismic Calibration........................................................................................................... 17
Seismic Reflection ............................................................................................................ 18
Reflection Results ......................................................................................................... 20
Seismic Refraction ............................................................................................................ 25
Refraction Results......................................................................................................... 25
Chirp sonar........................................................................................................................ 29
Bathymetry........................................................................................................................ 32
Gravity .............................................................................................................................. 34
vi
Physical Oceanography..................................................................................................... 37
Vertical Casts ................................................................................................................ 37
SVP, XCTD and XBT ................................................................................................ 37
Underway Systems: ...................................................................................................... 39
Mammal Interactions and Mitigation................................................................................ 40
Sea Ice............................................................................................................................... 43
Weather ............................................................................................................................. 45
Recommendations............................................................................................................. 46
Acknowledgements:.......................................................................................................... 47
References:........................................................................................................................ 48
Chapter 2: Acquisition and Processing of the Seismic Reflection Data..................... 49
Introduction:...................................................................................................................... 49
Source Parameters............................................................................................................. 52
Airgun Configuration and Firing Delays ...................................................................... 52
Shot Interval.................................................................................................................. 52
Source Wavelet ............................................................................................................. 53
Receiver Parameters.......................................................................................................... 59
Source-to-Receiver Offsets............................................................................................... 61
Data Recording ................................................................................................................. 62
CNT-2 Software Parameters ......................................................................................... 62
Data Storage.................................................................................................................. 62
Data Quality Monitoring and Seismic Watchkeeping .................................................. 63
Data Processing................................................................................................................. 64
Processing Workflow.................................................................................................... 64
Comments ..................................................................................................................... 66
Recommendations............................................................................................................. 68
Chapter 3: Canada Basin 2010 Canadian Hydrographic Service.............................. 69
Background ....................................................................................................................... 70
Summary ........................................................................................................................... 70
Sounding Methods ............................................................................................................ 71
Positioning Methods ......................................................................................................... 78
Data Collection ................................................................................................................. 81
Processing Methods .......................................................................................................... 85
Science .............................................................................................................................. 86
Expendable Deployments ................................................................................................. 86
Recommendations and Conclusions ................................................................................. 86
Acknowledgements........................................................................................................... 86
Chapter 4: Seismic Source Calibration......................................................................... 94
Source Signature Test: Shallow Tow Array Configuration............................................. 94
Equipment and configuration........................................................................................ 94
Source Signature Test: Deep Tow Array Configuration.................................................. 97
Equipment ..................................................................................................................... 97
Results............................................................................................................................... 99
vii
Shallow Tow configuration........................................................................................... 99
Model .......................................................................................................................... 103
Deep Tow Configuration ............................................................................................ 104
Model .......................................................................................................................... 106
Chapter 5: Ice and Weather Observations................................................................. 108
Introduction..................................................................................................................... 109
Daily Log: Beaufort Sea Unclos Operations 2010 ......................................................... 109
Weather Conditions ........................................................................................................ 128
Avos Equipment Operation and Malfunctions ............................................................... 129
Ice Specialist Work Station and Equipment ................................................................... 130
Satellite Imagery and Quality of Cis Ice Charts and Analysis........................................ 132
Communications ............................................................................................................. 132
Accomodations ............................................................................................................... 133
Support of Bridge Officers and Crew Personnel ............................................................ 133
Recommendations and Actions....................................................................................... 133
Acknowledgements......................................................................................................... 134
Appendix A .................................................................................................................... 136
Daily and Weekly Logs .................................................................................................. 136
Chief Scientist Daily Log............................................................................................ 137
NRCan Weekly Reports.............................................................................................. 146
Canadian Hydrographic Services Weekly Report ...................................................... 153
Appendix B: Bridge Instructions................................................................................. 163
Appendix C: Gundalf, G Gun Modeling Results ....................................................... 182
GUNDALF array modelling suite - 1150 in3, 6 m depth Array report ......................... 182
GUNDALF array modelling suite – 1150 in3, 12 m depth Array report .................... 198
viii
Figure Captions
Figure 1-1. Total ship's track .............................................................................................. 4
Figure 1-2 Science program wiring schematic, CCGS Louis S. St-Laurent 2010 ............ 6
Figure 1-3. Deep tow G-gun array design and photo of it being deployed. .................... 11
Figure 1-4. Seismic gun array configuration for shallow tow. The 150 in3 gun is in the
lead and the two 500's astern. ............................................................................... 12
Figure 1-5. Two Geometrics GeoEEL Streamers on the quarter deck of the LSSL........ 13
Figure 1-6. Deep tow configuration calibration test result, shot 5307. Top is a time
domain shot signature showing a zero to peak amplitude of 5.135 bar-m or 234
dB re 1 Pa at 1 m. Bottom is the frequency spectrum plot for this trace, showing
prominent power between 2 and 60 Hz with notching occurring at 65 Hz, caused
by the bubble pulse period. ................................................................................... 17
Figure 1-7. Geometric arrangement of the seismic reflection equipment. Top is the
shallow tow configuration, bottom is the deep tow (in ice) configuration. .......... 18
Figure 1-8. SeaStar mini CTD, About 2.5 cm in length. .................................................. 19
Figure 1-9. Cedar float that attaches over the repeater and A/D units. This one has been
drilled to house the miniature CTD ...................................................................... 19
Figure 1-10. An example of seismic data acquired during this mission. Top is the brute
stack and bottom is the final processed version of Line 16. ................................. 22
Figure 1-11. Map showing cruise track and line numbers............................................... 24
Figure 1-12. Location of sonobuoy deployments along track. ......................................... 25
Figure 1-13. Sonobuoy being deployed off the quarter deck............................................ 25
Figure 1-14. Top: an example of a sonobuoy record showing high data quality with
easily identifiable refractions arriving before the direct wave. Bottom:Plot file
results from deploying the sonobuoy ~17 nMi ahead of the vessel, so signals are
received fore and aft.............................................................................................. 27
Figure 1-15. Wiring schematic for Forward and Aft sonobuoy, dual receivers ............... 28
Figure 1-16: Sea Chest in Cradle ...................................................................................... 30
Figure 1-17: Interior of the chirp sonar sea chest showing transducer placement............ 31
Figure 1-18. Example of LSSL2010 Chirp sonar profile, 1500 m water depth, showing
>60m subseafloor penetration............................................................................... 32
Figure 1-19. CHS spot soundings via helicopter ............................................................. 33
Figure 1-20. US Coast Guard Cutter Healy ship track during which multibeam
bathymetric sonar and concurrent chirp subbottom profile data were acquired... 34
Figure 1-21. BGM-3 sensor SN 223 ................................................................................ 35
Figure 1-23. Top image shows gravity signal(blue line) with Healy breaking ice ahead of
LSSL. Notice the goodness of fit with the ArcGP grid (green line), with some
finer detail added. Bottom image shows gravity signal while LSSL breaks ice.
Notice the addition high frequency noise due to accelerations of ice contact. ..... 37
Figure 1-24. Vertical oceanographic profile data. Black dots are XCTD and XBT
locations and the green dots are full ocean depth Sound Velocity Probe locations.
............................................................................................................................... 39
Figure 1-25: TSG inlet temperature.................................................................................. 40
Figure 1-26: TSG salinity ................................................................................................. 40
Figure 1-27. Locations of mammal sightings. ................................................................. 42
ix
Figure 1-28. Daily Arctic sea ice extent as of September 6, 2010, along with daily ice
extents for years with the four lowest minimum extents. The solid light blue line
indicates 2010. ...................................................................................................... 43
Figure 1-29. 2010 Weekly ice coverage, Southern Canada Basin.................................... 43
Figure 1-30. Advanced Microwave Scanning Radiometer - Earth Observing System
(AMSR-E) images: Top is August 5, 2010 and bottom September 7, 2010,
showing differences in ice edge positions and approximate percent ice cover, as
interpreted from the imagery data. The white boxes outline our survey area....... 45
Figure 2- 31. Location map of the survey area. In total, 3763.3 line km of 16-channel,
short-offset seismic data were acquired during the Louis S. St-Laurent 2010
cruise. The seismic lines are shown in black. The start of each line is numbered
and indicated with a white dot. Pre-existing seismic data are plotted with thin
white lines. ............................................................................................................ 50
Figure 2-32: Source wavelets for the open-water towing configuration (source
depth = 5.5 m). The time series were derived by aligning and stacking the traces
recorded for various G-gun combinations during the August 10th calibrated
hydrophone measurements (cf. Chapter 4). Total source volumes are as follows :
A) 150 in3 ; B) 500 in3 ; C) 650 in3 ; D) 1000 in3 ; E) 1150 in3............................ 54
Figure 2-33: Relative power spectra for the open-water towing configuration (source
depth = 5.5 m). The various G-gun combinations were recorded during the
August 10th calibrated hydrophone measurements (cf. Chapter 4). Total source
volumes are as follows : A) 150 in3 ; B) 500 in3 ; C) 650 in3 ; D) 1000 in3 ; E)
1150 in3. ................................................................................................................ 55
Figure 2-34: Source wavelets for the icepack towing configuration (source
depth = 11.2 m). The time series were derived by aligning and stacking the traces
recorded for various G-gun combinations during the September 4th calibrated
hydrophone measurements (cf. Chapter 3). Total source volumes are as follows :
A) 150 in3 ; B) 500 in3 ; C) 1000 in3 ; D) 1150 in3. ........................................... 56
Figure 2-35: Relative power spectra for the icepack towing configuration (source
depth = 5.5 m). The various G-gun combinations were recorded during the
September 4th calibrated hydrophone measurements (cf. Chapter XX). Total
source volumes are as follows : A) 150 in3 ; B) 500 in3 ; C) 1000 in3 ; D) 1150
in3. ........................................................................................................................ 57
Figure 2-36: Relative power spectra for samples of the unprocessed data. Traces within
each shot record were stacked and then sets of 5 adjacent shots were summed.
The power spectra were computed over a 6.5 s window for A) LSL1001,
representing the open-water towing configuration with the 1150 in3 source, and
B) LSL1011 which was acquired with the icepack towing configuration with the
1150 in3 source. Receiver depths for LSL1011 ranged between 14 and 21 m in
this example, which noticeably suppresses power in the 35 to 50 Hz band. ........ 58
Figure 2-37: Comparison of receiver depth measurements obtained using the ODDI
SeaStar mini-CTD sensors with the GeoEel depth sensors on A) channel 1, and B)
channel 16. For the seismic data processing, measurements from the GeoEel
sensors were corrected to more closely match those of the SeaStar sensors by
applying the linear regression equations shown on the figure.............................. 60
x
Figure 2-38: Source to receiver offsets for A) the open-water towing configuration and B)
the icepack towing configuration. All distances are in metres. ........................... 61
Figure 2-39: Screen capture of the CNT-2 graphical user interface showing a message
log (top left), RMS noise chart (top middle), shot record (bottom left), and brute
stack (right). The software also allows the frequency spectra of each trace to be
monitored (not shown).......................................................................................... 63
Figure 3-40........................................................................................................................ 71
Figure 3-41. Knudsen 320B/R Plus sounder and PC interface was located in the
Oceanographic lab on the 300 level. The sounder is a dual frequency
configuration with the high frequency set to 12 kHz and low frequency reserved
for a 3.5 kHz transducer which is not installed..................................................... 72
Figure 3-42. 12 kHz transducer acoustic window in hull. ............................................... 73
Figure 3-43. transducer below landing on deck................................................................ 73
Figure 3-44. Helicopter spot soundings (yellow dots) collected during program. ........... 74
Figure 3-45. Spot sounding in open water, showing 12 kHz transducer slung below
helicopter............................................................................................................... 75
Figure 3-46. Knudsen sounder and laptop ........................................................................ 76
Figure 3-47. As recommended from previous year a permanent GPS antenna mount was
attached on the dash of the B105 .......................................................................... 76
Figure 3-48........................................................................................................................ 77
Figure 3-49. Typical echo traces (Echo Control window) when travelling in heavy ice
conditions.............................................................................................................. 77
Figure 3-50. MSat coverage map for CDGPS corrections .............................................. 78
Figure 3-51. NovAtel DL V3 GPS receiver in the equipment rack located on the bridge of
the ship. Positions were fed directly to seismic lab for distribution to various
computers/navigation programs............................................................................ 79
Figure 3-52. NovAtel software interface used to configure and monitor NovAtel GPS
receiver.................................................................................................................. 80
Figure 3-53. HyPack logging software ............................................................................ 80
Figure 3-54. Science winch with SV Plus v2 (sound velocity meter) depth range 5000
metres (SVP) mounted.......................................................................................... 81
Figure 3-55. The data were downloaded from SV Plus v2 using Smartalk v2.27 software.
............................................................................................................................... 82
Figure 3-56. The setup used for downloading XCTD/XBT using the MK21 USB DAQ –
Surface ship. Bathythermograph Data Acquisition system and LM-3A Hand-Held
Launcher (Lockheed Martin Sippican) ................................................................. 82
Figure 3-57. Locations of Sound Velocity casts in survey area. ..................................... 83
Figure 3-58. Figure 5 - SVP / XCTD graph/profiles ....................................................... 84
Figure 3-59. NRCan Seismic lab onboard CCGS LSSL showing Navigation (collection)
Knudsen sounder control and processing station.................................................. 85
Figure 4-60. Seismic gun array configuration for shallow tow. The 150 in3 gun is in the
lead and the two 500's astern. ............................................................................... 94
Figure 4-61. Design and measurement parameters of the Sercel G-gun array for
CPMSRRS 2010 ................................................................................................... 97
Figure 4-62. Fire point signal digitized from the LongShot fire unit. ............................. 99
xi
Figure 4-63. Shallow tow configuration calibration test result, shot 107. Top is a time
domain shot signature showing a zero to peak amplitude of 5.16 bar-m or 234 dB
re 1 Pa at 1 m. Bottom is the frequency spectrum plot for this trace, showing
significant power between 2 and 60 Hz with notching occurring at 100 to 120 Hz,
caused by the bubble pulse period. ..................................................................... 102
Figure 4-64. Comparison of the measured and modeled time-signature results. Note the
0-Peak amplitude of the model suggests 6.42 Bar-m (236 dB re 1 mPa @ 1 m),
while the measured result is 5.16 Bar-m (234 dB re 1 mPa @ 1 m). This
difference is consistent but unexplained. See Appendix C for modeling results
details. ................................................................................................................. 103
Figure 4-65. Deep tow configuration calibration test result, shot 5307. Top is a time
domain shot signature showing a zero to peak amplitude of 5.135 bar-m or 234
dB re 1 Pa at 1 m. Bottom is the frequency spectrum plot for this trace,
showing prominent power between 2 and 60 Hz with notching occurring at 65 Hz,
caused by the bubble pulse period. ..................................................................... 105
Figure 4- 66. Comparison of the measured and modeled time-signature results. Note the
0-Peak amplitude of the model suggests 6.33 Bar-m (236 dB re 1 mPa @ 1 m),
while the measured result is 5.29 Bar-m (234.5 dB re 1 mPa @ 1 m). This
difference is consistent but unexplained. See Appendix C for modeling results
details. ................................................................................................................. 106
Figure 4-67. A comparison of measurements made in 2009 with those of 2010. ......... 107
List of Tables
Table 1-1. Data summary................................................................................................... 9
Table 1-2. Summary of data archives .............................................................................. 10
Table 1-3. Line numbers and associated start and end times, locations and shot numbers.
............................................................................................................................... 21
Table 1-4. Summary of sonobuoy deployments .............................................................. 26
Table 1-5. LSSL2010 Chirp Data .................................................................................... 32
Table 1-6 *.rgs data record; fixed length 263 characters; space delimited ASCII; 29
record fields. (Note – need to add or replace table with description of the words
in rgs string.) ......................................................................................................... 36
Table 1-7 Physical Oceanographic vertical casts.............................................................. 38
Table 2-8: Shot and trace statistics for seismic reflection line segments collected during
this cruise. ............................................................................................................. 51
Table 2-9: Recording parameters used with the Geometrics CNT-2 software during the
survey.................................................................................................................... 62
Table 2-10: Summary of deconvolved CMP stacks derived from the 16-channel,
short-offset seismic data acquired during the Louis S. St-Laurent 2010 program.
............................................................................................................................... 66
Table 3-11. Major Equipment and Software Programs ................................................... 87
Table 3-12. Locations of XCTD (eXpendable Conductivity – Temperature – Depth) and
XBT (eXpendable Bathythermograph probes) and SVP (Sound Velocity Probe)88
Table 3-13. Ship Activity Log ......................................................................................... 90
xii
Table 4-14. Average amplitudes (0-peak and peak-peak) for calibration trials with the
shallow tow configuration..................................................................................... 99
Table 4-15. Table of amplitude values reported from the model compared with the field
measurement ....................................................................................................... 103
Table 4-16. Average amplitudes (0-peak and peak-peak) for calibration trials with the
deep tow configuration. ...................................................................................... 104
Table 4-17. Amplitude values reported from the model compared with the field
measurement ....................................................................................................... 106
xiii
Chapter 1: 2010 CBSRRS Summary
D.C. Mosher, J. Shimeld, C.B.Chapman
Introduction
Canada ratified Article 76 of the International Convention on the Law of the Sea
(UNCLOS) in 2003. This Article specifies a legal mechanism for defining the extended
continental shelf (ECS) beyond the 200 nautical mile limit. To assert sovereign rights
beyond 200 nautical miles, a country has ten years to collect the appropriate information
and submit a case to the United Nations Commission on the Limits of the Continental
Shelf (CLCS). Canada can exercise specified sovereign rights out to a distance of 350
nautical miles or further as a natural prolongation of Canadian territory. Rights include
jurisdiction in matters related to environment and conservation and powers over mineral
and biological resources on and below the seabed.
In order to extend boundaries beyond the 200 nMi limit, Canada must acquire
geophysical and geological data to define the limit of Canada’s continental shelf as
stipulated under Article 76. To this end, Canada has undertaken a program of data
acquisition along its frontier regions. Specific to this expedition, Natural Resources
Canada and Fisheries Ocean Canada, acting on behalf of the Government of Canada, is
operating a project in the western Arctic Ocean (Canada Basin) to acquire necessary
marine geophysical and geological data. This 2010 expedition represent the fifth
consecutive year of such activities in this region.
Although not yet a signatory of UNCLOS, the United States of America requires similar
data along its continental margin for eventual ratification; thus, a collaborative program
between Canada and the United States was established in 2008. This collaboration
included each country contributing an ice breaker to operate simultaneously in the icecovered waters of the western Arctic. Programs on each vessel acquire complimentary
data sets that will be shared and the vessels operate in tandem to ensure maximum data
quality. For 2010, the US contributed the US Coast Guard Cutter Healy (Healy) and
Canada, the Canadian Coast Guard Ship Louis S. St-Laurent (LSSL). For the Healy’s
part, the principal data acquired were multibeam bathymetry and high resolution
subbottom reflection profiles (Chirp). They also collected five piston cores. LSSL
collected seismic reflection and refraction data in addition to single beam bathymetry and
spot sounding data. Both vessels had gravimeters on board to measure the gravitational
potential on a continuous basis.
Objectives
The principal objectives of the LSSL2010 program were to, 1) acquire multichannel
seismic reflection and refraction data to establish sediment thicknesses along Canadian
and US western Arctic continental margins, and, 2) to acquire bathymetric sounding data
at specific locations along this same margin in order to validate bathymetric data acquired
1
by other means, for example by g. satellite altimetry or submarine, to establish baseline
information such as the 2500 m contour and foot of slope positions. Strategic ship track
lines were established to meet these criteria and to complement data acquired in earlier
phases of this program or exist from legacy programs from national and international
sources. Line orientations were also established to permit conducting scientific
investigations regarding the origin of the Amerasian Basin and associated submarine land
masses. Seismic system calibration experiments were also conducted to quantify sound
signal intensity levels produced by the seismic system.
Personnel
Scientific Personnel
1. David Mosher, NRCan, Chief Scientist
2. Jon Biggar, DFO, Hydrographer in Charge
3. John Shimeld, NRCan, Second Scientist
4. Borden Chapman, NRCan, Chief Technician
5. Jim Weedon, DFO, Hydrographer, watch keeping
6. Marcus Beech, DFO, Hydrographer, watch keeping
7. Jon Childs, USGS Scientific Liaison
8. Peter Vass, contract, Machinist and Mechanical Technician
9. Ryan Pike, contract, MechanicalTechnician
10. Paul Girouard, contract, Navigation and Data Curation Technician
11. Jim Etter, contract, Electronics Technician, watch keeping
12. Dwight Reimer, contract, Electronics Technician, watch keeping
13. Jamison Etter, contract, Compressor Technician watch keeping
14. Rodger Oulton, contract, Compressor Technician, watch keeping
15. Nelson Ruben, contract, Mechanical Technician
16. Jonah Nakimayak, contract, Mammal Observer
17. Dale Ruben, contract, Mammal Observer
18. John Ruben, contract, Mammal Observer
19. Walta Rainey, NRCan, GIS Support
CCGS Louis S. St-Laurent Personnel
Commanding
Officer
Chief Officer
First Officer
Second Officer
Third Officer
Chief Engineer
Senior Engineer
Andrew McNeill
Kerry Evely
Marian Punch
Reginald Prior
Adam Howell
Ronald Collier
Michael Willis
First Engineer
Second
Engineer
Third Engineer
Electrical Ofc
Electrical Ofc
Logistics Ofc
Boatswain
Carpenter
Joshua McInnis
Wayne Barter
Glen Nolan
Stephen Tucker
Anthony Engbers
Tony Walters
Rico Amamio
Gary Morgan
2
Winchman
Leading
Seaman
Leading
Seaman
Leading
Seaman
Seaman
Seaman
Seaman
Seaman
Seaman
E/R Tech
E/R Tech
E/R Tech
E/R Mechanic
E/R Mechanic
E/R Mechanic
E/R Mechanic
E/R Mechanic
E/R Mechanic
E/R Mechanic
Edward Bridgeman
David Bartlett
Stephen Archibald
Michael Worth
Daniel Dunlap
Allan Snow
Barney Noseworthy
Al Jarvis
Derrick Stone
Justin Bishop
(medevac)
Jeff Doane
Travis Tibbo
Cyril O'Brien
Jeff Simms
Kody Critch
Raine Jones
Wallace Jackman
Dean Kavanagh
Paul Jenkins
Chief Cook
Storekeeper
Storekeeper
Second Cook
Second Cook
Second Cook
Steward
Steward
Steward
Steward
Steward
Helicopter Pilot
Helicopter
Engin
Electronics
Tech
Ice Observer
Ice Observer
Medical Officer
Randy Turner
Jaimie Mizuik
Joe Gurney
Daryl Tobin
Fred Skanes
Wanda Oram Canning
Lawrence Jesso
Darlene Bedard
Cory Simms
Larry Royea
Winston Brinson
Christopher Swannell
William Duff
Stephen Wheeler
Bruno Barrette
Caryn Panowicz
(Healy)
Marcelle Collins
3
Figure 1-1. Total ship's track
4
Navigation, Record Keeping and Networking
The navigation and bathymetry data streams required by the various systems in
operation in the seismic lab were provided through dedicated fibre connections from the
bridge and the forward lab (Fig. 1-2). Differential GPS navigation was provided by the
science Novatel receiver. NMEA sentences from this system were multiplexed to the
ship’s speed log and gyro NMEA sentences and distributed to the seismic lab at 9600
baud via a dedicated fiber connection. The bathymetry was distributed to the lab at 4800
baud via a dedicated fiber connection from the Knudsen 12 Khz sounder located in the
forward scientific lab. The information received from the bridge was again multiplexed in
the seismic lab with the bathymetry and distributed at 19200 baud to the Regulus
navigation system and the seismic logger. The 9600 baud navigation stream was also
distributed to the sonobuoy GSCDIG logging system from a data line splitter located in
the seismic lab. The Regulus navigation system, running Build 4.8.21 of the software,
was used to view and log the scientific navigation. The Regulus system was also used to
view and update the electronic log. A GPS network time server was installed in the
seismic lab and provided a standardized time to all the systems in the lab. Their clocks
were updated every hour.
The navigation data were cleaned and merged using a text editor and the standard
GSCA programs ETOA, INTA and APLOT. Raw E-format, raw A-format and cleaned
and edited 10 second A-format files were saved on a daily basis and transferred to CD for
archiving. All seismic, gravity, sonobuoy, and Knudsen bathymetric and chirp data, as
well as their related logfiles, were also backed up to DVD for archiving. The compressor
watchkeepers and mammal observers maintained paper records of their observations.
These were reviewed on a daily basis and transferred to digital spreadsheets and archived.
A digital log of the daily scientific activities was maintained around the clock by the
watchkeepers and archived. A computer located in the radio room was used to control the
sonobuoys. The GSCADIG4 system was used for digitizing and recording the analog
sonobuoy signals as well as maintaining the Sonobuoy log sheets . The sonobuoy control
was managed from the seismic lab over the network using VNC Viewer, a remote
desktop management application. This software was also used for remote observation of,
and communication with, the compressor control computers. This arrangement was
changed during the last week of the cruise when a second sonobuoy antenna, looking
forward, was installed. The GSCDIG computer was moved to the radio room and the
coax cable normally used to carry the sonobuoy signal to the GSCDIG computer was
used to carry the trigger pulse up to the GSCDIG computer. The navigation was sent to
the GSCDIG computer via a dedicated fiber connection and two single port serial to fiber
converters. The compressor monitoring was moved to the CHIRP logger as the system
was not in use. The Knudsen 3.5Khz CHIRP system was a new addition for 2010.
All systems operated without any major problems. As in previous years, there
were some problems with the extremely slow links between some of the cabins and the
Seismic Lab. The problem was again traced to a duplex mismatch between the cabins’
media converters and the port they were connected to on the network switch in the
5
Figure 1-2 Science program wiring schematic, CCGS Louis S. St-Laurent 2010
6
LSL 2010 Data Summary
Line
Shotpoint
Start
End
Sonobuoy
No.
Start
End
LSL1001
LSL1002
LSL1003
LSL1004
2191222
2191905
2201500
2202130
2210826
2211256
2220216
2191544
2201459
2222139
2210826
2211256
2220216
2220821
1
4381
5996
19768
4380
5995
10767
12951
x
x
x
x
x
x
x
LSL1005
2220821
2221535
12952
15548
x
LSL1006
LSL1007
LSL1008
LSL1009
2242307
2251420
2260008
2261414
2251420
2252210
2261055
2262145
15449
18854
20510
22710
18853
20509
22709
24090
LSL1010
2262149
2281431
24091
31809
LSL1011
2281811
2301417
31810
40513
LSL1012
2301417
2311932
40514
46023
LSL1013
2320139
2320944
46024
47818
No.
Start
Knudsen
End
1
2
2250303
2251509
2251100
2252210
3
4
5
6
7
2261544
2270042
2270854
2272010
2280412
2262145
2270836
2271701
2280406
2281100
8
9
10
11
12
13
2282105
2290637
2291500
2292310
2301428
2310110
2290500
2291430
2292300
2300715
2302330
2310916
14
2320851
3.5Khz
12Khz
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Gravity
SVP
Launch
Time
XBT
Launch
Time
XCTD
Launch
Time
x
x
x
x
x
x
x
x
2221741
2211809
x
x
x
x
x
2251513
2260056
2261515
2270240
2271516
2280259
2260100
2281454
x
x
2290252
2291506
2300250
2301500
2311305
2311451
2311952
x
2320304
2320311
7
LSL1014
2321052
2331509
47819
53039
LSL1015
2341142
2342221
53040
55102
LSL1016
2350052
2351830
55103
58293
14
15
16
17
2330323
2350109
2350917
2321718
2331130
2350905
2351830
LSL1017
2381140
2391333
58294
63759
18
2390233
2391017
LSL1018
2391934
2392145
63814
64270
19
2392045
2392145
LSL1019
2460152
2470416
64318
70233
LSL1020
2470421
2480230
70234
74696
LSL1021
2480312
2500111
74697
84731
LSL1022
2500114
2502310
84732
90176
LSL1023
LSL1024
2502314
2520450
2520443
2541019
90180
97494
97493
109683
20
20a
21
22
2460935
2461056
2470455
2471642
2461056
2461735
2471255
2480038
23
24
25
26
27
28
29
30
2480326
2481658
2490505
2491702
2500117
2501327
2511640
2520754
2481130
2490300
2491300
2500104
2500919
2502130
2520101
2521613
x
x
xx
x
x
x
x
x
2321953
2331704
x
2341943
x
2321454
2330150
2331445
2340255
2341505
2350253
2351446
2351837
2360255
2371751
2371943
2380140
2381454
2381458
2390023
2391611
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
2471450
x
x
2480234
x
x
x
x
x
x
x
x
2391705
2401441
2402343
2411700
2421451
2422331
2460128
2461453
2470255
8
LSL1025
2541020
2541919
109684
111470
31
32
33
34
2521751
2530717
2532037
2541030
2530304
2531517
2540406
2541916
x
x
x
x
x
x
2542052
Table 1-1. Data summary
9
LSL 2010 Data Archive Summary
Seismics
DVD
No.
Gravity
Shotpoint
Start
End
DVD
No.
Line No.
Start
End
LSL1001
2202130
2210826
1
LSL1002
2210826
2211256
4381
5995
LSL1003
2211256
2220216
5996
10767
LSL1004
2220216
2220821
19768
12951
LSL1003
LSL1005
2220821
2221535
12952
15548
LSL1003
LSL1006
2242307
2251420
15449
18853
LSL1004
LSL1007
2251420
2252210
18854
20509
LSL1005
LSL1008
2260008
2261055
20510
22709
LSL1009
2261414
2262145
22710
24090
S3
LSL1010
2262149
2281431
24091
31809
LSL1008
S4
LSL1011
2281811
2301417
31810
40513
LSL1009
LSL1012
2301417
2311932
40514
46023
LSL1010
LSL1013
2320139
2320944
46024
47818
LSL1010
LSL1014
2321052
2331509
47819
50749
LSL1015
2341142
2342221
53040
55102
LSL1016
2350052
2351830
55103
58293
LSL1013
LSL1017
2381140
2391333
58294
63759
LSL1014
LSL1018
2391934
2392145
63814
64270
LSL1015
LSL1019
2460152
2470416
64318
70233
S8
LSL1020
2470421
2480230
70234
74696
S1
S2
S5
S6
S7
4380
S9
LSL1021
2480312
2500111
74697
84731
S10
LSL1022
2500114
2502310
84732
90176
S11
LSL1023
2502314
2520443
90180
97493
S12
LSL1024
2520450
2531600
97494
105899
LSL1024
2531600
2541019
105900
109683
LSL1025
2541020
2541919
109684
111470
S13
G3
G5
215
216
221
222
227
228
233
234
239
240
245
246
251
252
258
LSL1002
LSL1006
LSL1007
LSL1012
LSL1016
LSL1017
LSL1018
G6
LSL1019
LSL1020
G7
LSL1021
LSL1022
LSL1023
All Sonobuoys
LSL1024
LSL1025
Knudsen
All SVP, XCTD, XBT
Data and archive summaries
198
LSL1011
G4
All other data
A
End Day
LSL1001
G2
G8
Navigation
Mammal observers
logs
Electonic Log
Start Day
G1
Source calibration files
Seastar DVD CTD
Line No.
DVD
No.
Source
Start Day
End Day
K1
3.5Khz KEB & SGY
219
222
12Khz KEB
220
257
12Khz SGY
247
252 + 256
K2
Table 1-2. Summary of data archives
forward lab. The only major problem was the loss of all navigation data during the
second day. Although the seismic program had not yet started, this interruption in
navigation data meant that the gravimeter could not function. The problem was traced to
10
a malfunctioning serial to RJ45 converter in on the bridge. The exact cause of the
malfunction was impossible to determine but the converter eventually started working
and the problem did not recur.
A network radio link was again installed by the technicians from the USCGC Healy to
provide communication between the two ships over an IP phone connection for the
benefit of the science program. The installation went smoothly having the benefit of
previous experience. In order to isolate this network from the ship and science networks,
the network connection to the phone in the Conference Room was accomplished by
patching the radio link installed in the radio room directly to a network receptacle in the
conference room via the Forward Lab and After Lab patch panels.
Seismic Reflection and Refraction
The LSSL acquired multichannel seismic reflection and sonobuoy refraction data. The
four major equipment categories for seismic data acquisition are:
 Tow sled and G-gun equipment
 Compressor and air distribution system
 GeoEel streamer system
 Sonobuoy system
Figure 1-3. Deep tow G-gun array design and photo of it being deployed.
Full technical details of the systems can be read in Chapter 4 of the 2009 cruise report
(Mosher et al., 2009).
11
Seismic Source
The seismic source was an 1150 in3 pneumatically charged array (Fig. 1-3) of three
Sercel G-guns arranged in two configurations, a shallow tow-configuration for open
water (Fig. 1-4) and a deep tow configuration for ice operations (Fig. 1-3). For the deep
tow arrangement, there were two arrays for redundancy. A square wave trigger signal
was supplied to the firing system hardware by a FEI-Zyfer GPStarplus Clock model 565,
based on GPS time (typically about 19.5 seconds). Gun firing and synchronization was
controlled by a RealTime Systems LongShot fire controller, which sent a voltage to the
gun solenoid to trigger firing. There was a 56.8 ms delay between trigger and fire point.
Figure 1-4. Seismic gun array configuration for shallow tow. The 150 in3 gun is in the lead and the
two 500's astern.
12
Compressors
Pressurized air for the pneumatic G-guns was supplied by two Hurricane compressors,
model 6T-276-44SB/2500. No configuration changes were made for the 2010 Louis
program over the 2009 program. These are air cooled, containerized compressor systems.
Each compressor was powered by a C13 Caterpillar engine which turns a rotary screw
first stage compressor and a three stage piston compressor capable of developing a total
air volume of 600 SCFM @ 2500 PSI. The seismic system was operated at 1950 PSI and
one compressor could easily supply sufficient volume of air under appropriate pressure.
Unfortunately, these compressors have been plagued with mechanical problems requiring
extensive in-field repairs and off-season maintenance and modifications. Due to poor
“plumbing”, most of the high pressure lines on both machines have required reworking to
correct alignment issues at couplings and joints.
In 2010 there has been a decided decrease in the actual down time of both machines,
mainly due to the many upgrades and corrective maintenance provided by NRCan and
contract staff. In 2010 there was no lost survey time as a result of both compressors being
out of service at the same time. Technicians were able to “keep ahead” of service issues,
relying on one machine to be functional long enough to repair the other.
For the survey year 2010, a concerted effort was made to accumulate a maximum number
of operational hours on the newer Hurricane Compressor, HC #2. Approximately 500
operational hours were added to the 250 hours already on this machine. By the end of the
2010 survey HC #2 had run a total of 750 hours while HC #1 had run 1740 hours.
Seismic acquisition required a watchkeeper in the seismic lab and another in the
compressor container. The seismic lab watchkeepers (Etter and Reimer) were
responsible for data acquisition/recording, watching over-the-side equipment, gun firing
and log keeping. As well, a remote screen permitted monitoring compressor pressures
and alerts as well as
communicating with the
compressor watch-stander.
Compressor watchkeepers (Roger
Oulton, Nelson Ruben, Ryan Pike
and Jamieson Etter) were required
to watch over the compressor for
any failures for emergency shut
down and provide general
maintenance that might be required
during operations. During much of
the program, the ambient air
temperature was below zero
Figure 1-5. Two Geometrics GeoEEL Streamers on the
degrees Celsius, and with the high
quarter deck of the LSSL.
air flow rate through the enclosure,
13
the working environment within the compressor container was extremely uncomfortable.
Wind chill became a real issue and concern. As a result, watches were shortened to four
hours and a third watchkeeper (Ryan Pike) was added to the schedule.
Geometrics GeoEel Digital Streamer
Two identical GeoEel streamers were assembled in July 2010 while the vessel was along
side in St. John’s, NL (Fig. 1-5). For all deployments and recoveries, the streamer was
hand hauled and flaked on the deck. This technique allowed preparation of the streamer
before deployment (attaching it to the sled and preparing the floats and CTDs). Also, it
was faster than deploying and hauling in with the winches, thus preventing the streamer
from getting caught in the ice. On recovery, the streamer was pulled through a
submerged shackle in order to weight the streamer and keep it at depth and vertical off
the stern of the vessel.
No configuration changes were made for the 2010 Louis program. Please refer to the
2009 technical report (Mosher, 2009) for streamer “component placement”.
In 2010, two streamer problems were carried forward from the previous year:
(1) The issue of the electro-mechanical coupling connectors between streamer
sections working loose. While deployed, the connectors would loosen over time.
This allowed sea water ingress into the connectors causing high leakage values to
register on the deck equipment and eventually leading to an electrical short
circuit, damaging the connectors and/ or streamer sections;
(2) Leaky pressure case and connectors on the repeater located immediately aft of the
depressor, between the deck cable (or as it is referred to in the NRCan documents,
the “bundle cable”) and the float cable.
Steps taken to address issue #1:
In 2010 during the assembly process, an “O” ring was placed over the groove of each
electro- mechanical connector, into the small gap between the connector collar and
connector body. The “O” ring served to stabilize the collar and dampen the vibration
which caused the collar to loosen during towing. With the “O” ring in place,
approximately six wraps of electrical tape were wound around the connector collar to
increase the outside diameter of the collar and hold the “O” ring in place. A #26 hose
clamp was secured over top the electrical tape and carefully located in such a way as to
span the connector collar, overtop the “O” ring and the connector body. Once securely
tightened, the hose clamp forced the “O” ring into the tight groove between the connector
collar and the connector body, further preventing the connector from loosening. This
proved to be a successful technique preventing the connector loosening.
Steps taken to address issue #2;
14
The water ingress/ repeater issue was dealt with while at sea. This problem was a holdover from previous years and once again arose early in the 2010 cruise.
Shortly after gear deployment, streamer leakage and soon after, streamer current
increased. The problem was traced to the repeater immediately behind the tow sled. Upon
removing the repeater, sea water was found in the electro- mechanical connectors. After
several recoveries, sea water was also discovered inside the repeater pressure case. On
one occasion the sea water had damaged the electronic circuit boards rendering this
repeater unserviceable.
In 2009, an attempt was made to cure the ingress of sea water into the repeater/ connector
using a clamp and support bracket system. The “on board” fabricated clamp secured the
deck (bundle) cable to the back of the tow sled using a four point tow harness. The
support bracket secured the deck (bundle) cable mould and the float cable mould while
rigidly supporting the repeater. This helped address the issue immensely but again in
2010, the sea water was found inside the repeater pressure case and/ or the electromechanical connectors.
On careful examination it was observed that the outside diameter of the potted electrical
moulds for the deck (bundle) cable and the three available float cables were quite
different. Further, it was observed that there was a torque being applied to the repeater
pressure case as it was secured to the support bracket. The support bracket was also only
limiting movement of the repeater in one plane. To address these issues, a new bracket
was fabricated from 2”x 2” x ¼” aluminium angle. The inner surface of the aluminium
angle was machined on one end to allow for the difference in the outside diameter of the
float cable which had a larger OD than the deck (bundle cable). Also specially fitted
collars were fabricated to slide over the repeater body to fit the angle bracket securely. As
with the other streamer sections, an “O” ring/ tape and hose clamp arrangement was used
to prevent the connector collars from loosening. The entire assembly was secured to the
aluminium angle bracket using seven- #36 hose clamps. By properly aligning the three
components, deck cable, repeater and float cable, water ingress was stopped. Also the
“L” shape of the aluminium angle offered structural support in both the vertical and
horizontal plane, thus stopping any movement of the assembly.
As the OD on the port and starboard streamer float cable moulds were found to be
different, two separate angle brackets had to be fabricated. Separate port and starboard
repeater collars were also made to adapt the repeater to the different aluminium angle
brackets.
The final step to reduce the water ingress into these repeaters involved disassembling the
port bundle and increasing the layback of the deck (bundle) connector from 3 feet to 10
feet. This placed the deck (bundle) clamp approximately 10 feet behind the tow sled. The
four legs of the pull cable bridle, which previously had been connected directly to the tow
sled, were connected to a new seven foot single cable secured onto the back of the sled.
This single cable served to reduce the “shock” transferred to the clamp and thus the deck
15
(bundle) cable. With less movement on this new deck cable/ repeater/ tow cable
assembly, there was no water ingress into the repeater pressure case or repeater
connectors for the remainder of the program.
During an eight day tow, no streamer issues arose and streamer leakage remained at a
minimum. On disassembly all connections over the streamer length remained
comparatively tight and there was no observed water ingress at any of the connector
joints.
The hardware performance of the Geometrics GeoEel system in 2010 was judged as
“acceptable”. A considerable portion of the 2010 program involved open water towing so
the stress on the streamer would be similar to that of any open water seismic program.
The modifications to the pulling arrangement as discussed above helped to eliminate
some of the issues plaguing the seismic operation in previous years.
As stated, much of the program was in ice free or reduced ice filled waters. There was no
incident where the streamer had to be deployed or recovered in rafting ice conditions or
with sea ice under compression. Over the past years, these difficult environmental
conditions proved significant to maintaining streamer functionality.
Modifications to improve stability of the connectors at the rear of the tow sleds and
between streamer sections meant that less gear retrieval was necessary, reducing the
chance of damage due to handling. There are a number of streamer components which
will require Geometrics “factory service” before the 2011 season. These components will
be grouped and inventoried before being sent to the manufacturer for repair.
16
Seismic Calibration
Figure 1-6. Deep tow configuration calibration test result, shot 5307. Top is a time domain shot signature
showing a zero to peak amplitude of 5.135 bar-m or 234 dB re 1 Pa at 1 m. Bottom is the frequency
spectrum plot for this trace, showing prominent power between 2 and 60 Hz with notching occurring at 65
Hz, caused by the bubble pulse period.
Two separate seismic calibration experiments were implemented during this program;
one on the shallow tow arrangement and one on the deep tow arrangement. Most data
were acquired throughout the program with the deep tow configuration. A full write up
on these experiments is provided in Chapter 3. In both instances, 0-peak sound pressures
were found to measure at 234dB re 1 Pa at 1 m and peak-to-peak pressures of 238 dB re
1 Pa at 1 m. A much improved signature was recorded over last years trials, indicating
that there was indeed a problem with last year's experiment and results from that effort
should be ignored.
17
In addition, an accurate time gap between trigger and fire points was recorded. The fire
break point signal from the LongShot firing unit was recorded on a separate channel
(channel 2) of the GSCDIG #4, along with the calibration trace on channel 1.
Figure 1-7. Geometric arrangement of the seismic reflection equipment. Top is the shallow tow
configuration, bottom is the deep tow (in ice) configuration.
Seismic Reflection
Full details of the seismic reflection acquisition and processing component of the
program are provided in Chapter 2. For most of the program the streamer was towed
from the aft end of the G-gun tow sled at a depth of 11.2 m (see Fig. 1-7, deep tow
configuration). For Lines 1 to 5, in open water, the shallow tow configuration was
employed (Figs. 1-4 & 1-7). Two active 150 foot streamer sections were included in the
overall streamer configuration. Total streamer length was approximately 300 m.
The active elements in the GeoEel streamer were Benthos Geopoint hydrophones. There
were eight groups of four Geopoint hydrophone cartridges in each active section. Thus,
18
with two active sections, the streamer had a total of 16 active channels, each with four
Geopoint cartridges. Seismic signals received by the hydrophone elements in the streamer
were digitized by 24 bit A/D modules which form part of the streamer system. Digitized
seismic signals were sent up the cable as USP data packets to the recording system. A
Geometrics software program called Stratavisor provided streamer control, logging and
display of the data. Stratavisor version 5.31 was implemented for most of the 2010
program and was found to be stable.
Included in the Stratavisor software was a streamer depth
monitoring option. Depth sensors were fitted inside the
forward end of each active section. The active section tow
depth was displayed on the Stratavisor monitoring software.
Wooden floats were added to cover the A/D and repeater
modules (Fig. 1-9). These floats added significant buoyancy
to the streamer and helped immensely in maintaining
appropriate tow depths. Miniature SeaStar CTD’s were
mounted in the floats at the A/D converters and on the tail
section of the streamer. These CTD’s provided depth
information after recovery of the streamer, permitting us to
Figure 1-8. SeaStar mini
understand streamer dynamics during operation (Fig. 1-8).
CTD, About 2.5 cm in
Temperature and salinity data were also acquired with these
length.
CTD’s, showing salinity in the range of 27 to 28 psu and
temperatures on the order of -1.2 to -1.5ºC. Full description of the CTD’s are provided in
the 2009 cruise report (Mosher et al., 2009) and in Chapter 2.
Seismic reflection data were post-processed using Claritas seismic processing software.
Original SEG-D files were assembled into line segments and converted to SEG-Y format.
Brute stacks were generated at sea and printed to verify the data quality. Final postprocessing was also completed at sea and included : static shifts for recording delay,
field time break, and firing delay ; debias ; design of wiggly line CMP bins at a 12.5 m
interval ; matching and
interpolation of receiver depths for
each shot record ; bandpass
filtering (3/8/140/240 Hz) ; F-K
filtering ; T-squared amplitude
scaling ; trace balancing ; trace
editing based on frequency
characteristics ; minimum phase
conversion ; source signature
deconvolution ; gapped
deconvolution ; CMP stacking ;
primary multiple suppression using
Figure 1-9. Cedar float that attaches over the
an autoconvolution model with
repeater and A/D units. This one has been drilled to
adaptive subtraction ; poststack
house the miniature CTD
coherency filtering ; finite
19
difference migration using 2-D velocity models derived from previous sonobuoy results ;
linear amplitude scaling (5 dB/s below seafloor) ; phase shift ; and time-varying lowpass
filtering. Data quality was excellent for the most part. Heavy ice conditions requiring
extra propeller revolutions and heavy sea states during several days of the open water
surveying created most of the noise apparent on seismic data. See Figure 1-10 for a
comparison of brute stack and processing seismic results and Chapter 2 for the full
acquisition and processing report.
Very little time was lost this season due to seismic equipment failure; an estimated 18
hours total. The only significant problem was streamer leakage at the foremost repeater
unit in the streamer. The most significant block of time lost was 14 hours on line 21/22
(Day 239) at the northernmost portion of the survey, due to streamer leakage. Ultimately,
we finished the line in multibeam mode only while we effected streamer repairs. With
redesign of the towing harness, the situation seems to have been resolved. Data quality
were affected by bad sea states in open water conditions, particularly during days
227/228 on Line 10 and day 250 on Line 21. Data quality were also affected by
excessive propeller wash in ice conditions. A streamer failure on August 27 (JD 239)
between 0150 and 0630 and resulted in acquisition on only 8 active channels, which also
affected data quality.
Reflection Results
25 seismic reflection lines totalling 111460 seismic shots and 3673 line-km of seismic
reflection data were acquired over the course of 29.5 acquisition days (Figure 1-11; Table
1-3). Lines 1-5 were acquired on the Canadian Beaufort Shelf and uppermost slope to tie
into existing industry data sets in this region (Fig. 1-11). The shallow tow configuration
was used for these lines. The original intent was to acquire these data at the end of the
program, but because of delays in obtaining permissions to acquire data in the US
Exclusive Economic Zone (EEZ), this portion of the program was implemented first. By
August 11th, US approvals were obtained and we proceeded to acquire data in the US
EEZ.
Lines 6 to 11 were acquired within the US EEZ along the Alaska margin. By Day 230, at
the end of Line 11, we were outside of the US EEZ, but continuing work for US interests
with lines along Northwind Ridge. These included Lines 12-14 from NW Ridge to tie to
the existing grid of seismic data in the central portion of the basin. These lines were
modified to optimize ship time. Line 12 was oriented to attempt to tie into Grantz's 1993
lines (Grantz et al., 2004).
Line 15/16 runs from the north end of Northwind Ridge to the basin in a NE direction, in
an attempt to cross a basement ridge and graben structure at an orthogonal angle (see Fig.
1-11). Once the crossing was made the line was terminated as northern objectives were a
priority and shared time with the Healy was running out. It was hoped that we could tie
in this line from the east as the two ships headed south again.
20
Line
No.
Start
Time
Lat
LSL1001
2202130
71
09.5487
LSL1002
2210826
70 29.4577
LSL1003
2211256
70 21.3779
LSL1004
2220216
71 11.5090
LSL1005
2220821
70 59.0587
LSL1006
2242307
LSL1007
2251420
LSL1008
2260008
LSL1009
2261414
LSL1010
2262149
LSL1011
2281811
LSL1012
2301417
LSL1013
2320139
LSL1014
2321052
LSL1015
2341142
LSL1016
2350052
LSL1017
2381140
LSL1018
2391934
LSL1019
2460152
LSL1020
2470421
LSL1021
2480312
LSL1022
2500114
LSL1023
2502314
LSL1024
2520450
LSL1025
2541020
71
39.3983
72
15.8884
72
46.4979
73
25.4160
73
55.3428
71
48.2714
74
43.5333
76
10.5362
76
14.5613
78
06.8297
78
22.9335
82
32.6675
81
47.34738
76
32.3485
76
51.5339
75
21.6690
72
25.2838
70
59.5841
71
30.3010
73
50.9258
Long
135
31.0039
134
18.4119
135
08.7449
136
36.4786'
137
46.8283
148
11.189
145
24.4562
145
22.2098
145
19.8999
145
19.1072
151
43.5665
150
02.8734
156
12.6693
154
09.2348
153
16.3645
150
43.3595'
138
55.8290
128
13.6112
128
44.7508
136
03.0370
136
25.1744
136
59.4271
137
36.2321
131
29.5314
140
21.1254
End
Time
Lat
2210826
70 29.4577
2211256
70 21.3779
2220216
71 11.5090
2220821
70 59.0587
2221535
71 18.8510
2251420
2252210
2261055
2262145
2281431
2301417
2311932
2320944
2331509
2342221
2351830
2391333
2392145
2470416
2480230
2500111
2502310
2520443
2541019
2541919
72
15.8884
72
47.6661
73
25.7201
73
55.0725'
71
53.1010
74
43.5333
75
49.3355
76
14.9631
76
35.3846
78
23.5169
78
59.5373
81
45.6753
81
43.3297
76
51.6771
75
22.4588
72
25.4835
70
59.8249
71
29.7805
73
50.8787
73
42.0085
Long
134
18.4119
135
08.7449
136
36.4786
137
46.8283
136
59.5461
145
24.4562
145
22.7278
145
20.275
145
18.2737
151
22.3980
150
02.8734
156
10.8935
154
06.2002
146
24.1893
150
47.7797
145
07.4122
128
37.6587
127
18.2167
136
01.7003
136
24.8971
136
59.3035
137
36.2238
131
29.5214
140
20.8305
142
29.3098
Shot
Start
Shot
End
1
4380
4381
5995
5996
10767
19768
12951
12952
15548
15449
18853
18854
20509
20510
22709
22710
24090
24091
31809
31810
40513
40514
46023
46024
47818
47819
53039
53040
55102
55103
58293
58294
63759
63814
64270
64318
70233
70234
74696
74697
84731
84732
90176
90180
97493
97494
109683
109684
111470
Table 1-3. Line numbers and associated start and end times, locations and shot numbers.
21
Figure 1-10. An example of seismic data acquired during this mission. Top is the brute
stack and bottom is the final processed version of Line 16.
During transit to the north, LSSL developed propeller shaft problems which took ~36
hours to repair. This delay forced us to abandon plans to shoot a seismic line north
through Stefansen Basin up to Alpha Ridge to 85ºN. We opted instead to start on
Nautilus Spur and shoot Line 17 from west to east towards the north side of Sever Spur,
and tie into the Borden Island spot sounding line. Ice conditions were heavy. The
streamer failed about half way through this transect. We were able to tie into 2009 lines
20/21, but were not able to complete the transect. As a result, we completed the line and
to tie to the spot sounding line with Healy multibeam only and LSSL broke ice for Healy.
The intent was to tie the line up to the 2500 m contour, but at 1630, Day 240 (August 28),
we broke the survey to go on a medical evacuation.
Following the med-evac, we had only 1.5 days left for joint operations with the Healy.
To take advantage of this little remaining time, we ran a line (Line 19) from the north
side of McClure Strait westward to tie into Line 09-31. This line forms the northernmost
margin tie-line along the Canadian Archepelago margin; the other three being acquired in
2007. After tying to 09-31 we turned south on Line 20/21/S22 in order to make an
22
eastern tie line between these margin perpendicular lines and to tie the grid in to the
Beaufort margin, the FGP lines that exist there and our own few lines that were acquired
at the start of the program. Healy was able to break ice for us until September 4th (Day
247) at 12:00h PST on line 20/21/22, after which we broke ice for ourselves. Ice
conditions were relatively light, however.
From Line 21/22, we turned east on Line 23 to acquire a margin-parallel line along the
upper portion of the Beaufort Slope. The original intent was to transit this line but
weather did not permit recovery of the seismic equipment, so we continued surveying.
We tied into FGP line 87-1 and turned northwest to acquire a dip line (Line 24) down the
length of the MacKenzie fan delta and tie to the existing grid within the basin. We then
turned SW on Line 25 to cross the gravity low in the central basin and terminated the line
just after completing the crossing, thus terminating the seismic program at 1200h
September 11, 2010.
23
Figure 1-11. Map showing cruise track and line numbers.
24
Seismic Refraction
Ultra-Electronics marine sonobuoys
(Model 53C) were deployed to acquire
wide angle reflection and refraction data
for velocity determination, required to
convert seismic reflection traveltime to
depth. Sonobuoys were deployed at
irregular but frequent periods, particularly
over line segments meant to be greater
than 35 km in length (see Fig. 1-13, Table
1-4). The sonobuoy hydrophone was
Figure 1-13. Sonobuoy being deployed off the
quarter deck
activated at 60 m water depth. Sonobuoyreceived seismic signals were radiotelemetered to two Winradio Model WR-G39WSBe VHF sonobuoy receivers. A stacked
Yaggi array of two Andrews DB292-C VHF antennas, cut to respond to frequencies
between 150 and 160 MHz were fitted to the aft railing, port side of the “crow’s nest”.
This array has a 15º beam width pattern focussed astern of the vessel. A high pass RF
filter prevented damage to the sonobuoy receivers from the strong signal of the
Helicopter DF beacon. Signal reception was excellent, often received beyond 35 km.
These signals were recorded on GSCDIG #4 as standard SEG-Y files. The seismic
trigger pulse from the Zyfer clock was supplied to the digitizer to initiate recording. The
record window length was only
slightly shorter than the fire period.
Several sonobuoys were deployed
ahead of the vessel via helicopter drop
in order to acquire approaching and
departing refraction limbs. A single
Yaggi array was mounted on the rail
on Monkeys Island to receive the
sonobuoy radio signals during the
approach. This forward signal was
recorded on a separate channel from
the aft antenna of the GSCDIG, so two
separate SEGY files were created for
the one deployment (see Fig 13).
Refraction Results
34 sonobuoys were deployed with no
complete failures (Fig. 1-12 and Table
Figure 1-12. Location of sonobuoy deployments along
1-4), although some had poor signal to
track.
noise issues. High quality records
were obtained for the majority (Fig. 1-13). Helicopter and ship-to-ship communications
resulted in HF intereference on digitized records, but this interference was not fatal. In
addition, periodic bursts of noise of unknown source appear on the records.
25
SB#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
20a
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Start
End
Time
Lat. N
Long. W
Time
Lat. N
Long. W
225030300
225150900
226154400
227004151
227085400
227200400
228041212
228210508
229000637
229150000
229231000
230143824
231011028
232085125
233032249
235010900
235091712
239023320
239204501
246093532
246105601
247045538
247164151
248032614
248165746
249050446
249170200
250011724
250132723
251164032
252075409
252175100
253071653
253203700
254102951
71 49.1747
72 19.1675
73 31.1373
73 46.9449
73 23.406 3
72 47.9686
72 25.7874
71 58.6938
72 38.1202
73 12.6702
73 43.2974
74 44.3399
75 12.6063
76 14.3705
76 26.9973
78 23.4513
78 40.3398
82 06.0357
81 45.2101
76 39.7429
76 40.8499
76 49.2360
76 01.1420
75 20.7535
74 27.6277
73 40.6054
72 42.388
72 25.1613
71 36.5063
71 22.6800
71 38.8588
72 16.5750
72 41.6563
73 25.4150
73 50.7931
147 26.6461
145 24.5047
145 19.7748
145 44.8650
147 01.8250
148 54.1545
150 02.2801
151 44.6130
151 21.2573
151 00.1861
150 41.4246
150 07.6549
152 07.1913
154 18.4270
149 37.8642
150 38.2894
148 04.9256
133 22.3962
127 44.7812
130 49.3772
131 10.5827
136 01.9116
136 08.8133
136 23.7082
136 22.1561
136 29.8982
136 52.928
136 59.5373
137 20.4561
133 11.2600
131 58.1249
134 02.0740
135 31.9230
138 26.9840
140 23.7769
225110300
225221000
226214500
227083600
227170055
228000406
228110000
229000500
229143000
229230000
230071500
230233000
231091600
232171837
233113000
235090500
235183000
239101700
239214443
246105601
246173522
247125537
248003813
248113000
249030000
249130000
250010400
250091900
250213000
252010118
252161300
253030400
253151711
254040449
254191542
71 08.3785
72 46.6661
73 55.0725
73 24.3061
72 59.8980
72 26.1131
72 04.6601
72 31.6032
73 10.5805
73 42.5655
74 16.2145
75 10.8946
75 32.1232
76 19.3421
76 33.0062
78 39.9388
78 59.5373
81 51.8505
81 43.3297
76 40.8499
76 45.6914
76 16.6892
75 30.1987
74 48.9657
73 48.3134
73 10.4438
72 25.8665
71 54.0124
71 05.8280
71 26.7680
72 02.2545
72 31.1848
73 02.5191
73 35.3218
73 42.0175
146 00.2386
145 22.7278
145 18.2737
146 58.8830
147 16.8283
150 01.3067
151 04.6995
151 25.2516
151 01.4895
150 41.6940
150 19.9271
151 39.9034
153 49.7580
152 26.0675
147 21.4272
148 08.5123
145 07.4122
130 02.5758
127 18.2167
131 10.5827
133 05.0660
136 06.0822
136 20.5914
136 17.1150
136 19.7559
136 41.5793
136 59.0075
137 21.8463
137 33.2909
132 12.8410
131 12.9282
134 54.4797
136 53.5755
139 11.5323
142 29.2969
Table 1-4. Summary of sonobuoy deployments
Although it will take time to process and analyse the sonobuoy results, it is clear from a
cursory look that there are distinct changes in the slopes and amplitudes of refracted
arrivals from location to location. These differences are no doubt related to velocity and
geologic changes. These data will provide a regional 3D model of crustal velocities and
basement affinities, holding great promise to vastly extend the understanding of Canada
Basin’s geologic history. As a trial, we deployed a sonobuoy ahead of the Louis from the
helicopter. In this way, we could receive both limbs of a refraction profile. We mounted
a forward antenna on monkey's island to receive the signal ahead of the vessel. After
several attempts, Sonobuoy 34 was successfully received (Fig. 1-14). The principal
issue
26
Figure 1-14. Top: an example of a sonobuoy record showing high data quality with easily
identifiable refractions arriving before the direct wave. Bottom:Plot file results from
deploying the sonobuoy ~17 nMi ahead of the vessel, so signals are received fore and aft.
was the the GSCDIG could not receive two channels for long record window lengths,
without introducing errors in the digitized signal start time. The work-around was to
record on only one channel but switch receivers when the vessel was beside the sonobuoy
(see schematic below). The life span of the sonobuoys is too short (8 hours) to get the full
range of refractors, but the trial was successful and perhaps for next year we can extend
the life of the sonobuoys to allow this type of deployment.
27
Figure 1-15. Wiring schematic for Forward and Aft sonobuoy, dual receivers
28
Chirp sonar
To provide sub-bottom sediment thickness measurements during parts of the 2010 CCGS
Louis S. St. Laurent UNCLOS program, a chirp sonar system that could operate in ice
was developed to tow from the stern of the vessel. Because of the configuration and
requirement to tow it from the heel block on the stern of the vessel, it could be operated
only concurrent with the shallow tow seismic configuration (see Fig. 1-7). Its use,
therefore, was limited to open water tow only for this field season, thus was utilized on
lines 1 to 5 (Table 1-5). Data quality was excellent, however, and ways will be studied in
which the system may be able to be used for the entire program for next season.
A Knudsen 3260 transceiver and associated control computer were located in the Seismic
Lab. Data were logged onto the PC’s hard drive and off-loaded over the ship’s science
network. Navigation data were derived from the ship’s navigation receivers over the
science network.
The array consists of 12- Massa TCH1075 transducers in an electrically “parallel”
arrangement, each with a nominal impedance of 250 ohms, a net transmitter load at 3.5
kHz, approx 27 ohms.
Array design Criteria: by Peter Simpkin
Beam Pattern Calculations for 12 transducer array of Massa TR1075 transducers:
Constants used:

Active Diameter of individual transducer 7.0” = 17.8cm

When formed into a 4 x 4 array with the four corner transducers missing, the
active diameter is taken as 71.2 cm (28”)
The half beamwidth for the main lobe pattern is estimated from the nomograms found in
“Principles of Underwater Sound” by R.J. Urich.
The beamwidth information is extracted for Intensity Reductions of -3dB and -10dB from
the on-axis intensity for frequencies of 2, 4 and 6 kHz .
Frequency
2 kHz
4 kHz
6 kHz
-3dB Half Angle
32º
15º
11.5º
-10dB Half Angle
60º
27º
18º
29
Figure 1-16: Sea Chest in Cradle
An aluminium sea chest was designed and constructed specifically to house the 12
transducer array and to bolt up directly under the depressor weight frame on the Port Tow
sled. The sea chest was filled with approximately 150 gallons of NoTox II antifreeze.
The electrical connection to the Knudsen 3260 Chirp transceiver was via electrical deck
and lead-in cables and through a connector located on the top of the sea chest. Also fitted
to the top of the sea chest were vent and fill piping and a pressure equalization bladder
(See Fig. 1-16). A suitable cradle was constructed to hold the sea chest while in storage
onboard the vessel and while in long term storage after use. Suitable zinc sacrificial
anodes were fitted to help reduce affects of salt water corrosion on the aluminium
components. All stainless steel 316 hardware was used in the construction and assembly.
The overall weight of the sea chest, filled with antifreeze was 2250 pounds.
Inside the sea chest a chassis was fitted to accommodate the mating pair ends of the
twelve electrical cables coming from the 12 transducers (Fig. 1-17). A single connector
exited the same chassis and mated to the connector which passed through the lid of the
sea chest. This electrical cable completed the connection to the umbilical cable from sea
chest to the surface, then to the deck cable and into the Knudsen 3260 Chirp transceiver.
The maximum cable length from the transceiver to the sea chest was 150 feet.
30
Figure 1-17: Interior of the chirp sonar sea chest showing transducer placement
A tow depth for the sea chest of 60 feet was fixed by a length of 1” steel cable fitted to
the top of the tow sled depressor weight. The 1” cable was configured to be similar to the
tow cable used to support the sled when towing air guns in ice, but was 30 feet longer. By
fixing the tow cable to 60’ the inside pressure on the transducer array was set to 2
atmospheres allowing transmit power to operate up to 7.2 kWatts. To deploy the
depressor weight and sea chest, the tugger winch located on the “tween” deck over the
ship’s quarterdeck had to be changed. The combined weight of sea chest and depressor
was 6900 pounds and a winch and cable was installed to safely carry the load.
The pull point location on the top of the tow sled depressor was moved aft to cause the
sled to tow almost level at 4.5 kts. On the first deployment, a pitch and roll system was
fitted to the sled to measure its orientation. This trial showed that the usual fixed tow
point on the depressor was too far aft, causing the sled to tow nose down approximately
7- 9 degrees. By moving the point further aft, the sled pulled well with an angle of
approximately 1 degree from horizontal.
Conclusions:
Data collected from the Chirp were judged to be of excellent quality (see Fig. 1-18).
Unfortunately the program had some major changes and the opportunity to operate the
Chirp system was brief. It is hoped that this tool could be adapted to operate in tandem
with a second sled equipped with the air gun array.
31
Line
no.
Start
Time
Lat. N
Long. W
End
time
Lat. N
Long. W
LSL1001
LSL1002
LSL1003
LSL1004
2202130
2210826
2211256
2220216
71 09.5487
70 29.4577
70 21.3779
71 11.5090
135 31.0039
134 18.4119
135 08.7449
136 36.4786'
2210826
2211256
2220216
2220821
70 29.4577
70 21.3779
71 11.5090
70 59.0587
134 18.4119
135 08.7449
136 36.4786
137 46.8283
LSL1005
2220821
70 59.0587
137 46.8283
2221535
71 18.8510
136 59.5461
Table 1-5. LSSL2010 Chirp Data
Figure 1-18. Example of LSSL2010 Chirp sonar profile, 1500 m water depth, showing >60m subseafloor
penetration.
Bathymetry
As in the past four years of this program, the Canadian Hydrographic Service (CHS)
performed bathymetric survey operations in conjunction with the NRCan seismic
operations. Two sounding techniques were employed: conventional ship sonar and
helicopter spot soundings. The ship navigated along pre-determined transects and the
helicopter was deployed to collect spot sounding data between the survey lines. The ship
logged 8355 line kilometres of bathymetry data and 61 spot soundings were acquired via
helicopter (Fig. 1-19). Virtually the same equipment was used for both platforms. The
USCGC HEALY joined the program on August 7th and departed September 4th, during
which time additional hydrographic data were collected with their EM122 deep water
multibeam and Knudsen Chirp profiler systems (Fig. 1-20).
32
The LSSL collected soundings using a Knudsen 320B/R Plus sounder attached to a hullmounted 12 KHz transducer. The system used Chirp pulse generation technology. The
echo sounder performed well although the settings in deep water (>2500 metres) were set
at maximum values to
acquire the data. As is
common when sounding in
ice, bottom detection was
sometimes lost due to
interference from ice.
Watchstanders (Weedon and
Beach) processed data in near
real-time to eliminate outliers
and maintain bottom
tracking. The sounder was
active for the entire
expedition. Knudsen Echo
Control Client V1.47 and
Echo Control Server V1.44
software were used for
acquisition and PostSurvey
V2.24 software was used for
viewing during post
processing of the data. Data
were recorded in Knudsen
native KEB format. Attempts
Figure 1-19. CHS spot soundings via helicopter
to also record in SEG-Y
format resulted in software
crashes. CARIS (Computer Assisted Resource Information System) GIS v4.4 was used
for managing, compiling, and visualizing results of the processed bathymetric data.
CARIS HIPS/SIPS v6.1 (Hydrographic Information Processing System/Sonar
Information Processing System) was used for survey data processing of positions and
depths.
33
Figure 1-20. US Coast Guard Cutter Healy ship track during which multibeam bathymetric sonar and
concurrent chirp subbottom profile data were acquired.
Gravity
A Bell Aerospace BGM-3 gravity meter, SN 223, was installed on the vessel in St. John's
in July 2010. The instrument was provided by the Woods Hole Geopotential Instrument
Pool under contract to the USGS. The instrument is scheduled to remain on board the
vessel until arrival in St. Johns on or about November 20, 2010.
This gravimeter is virtually identical in all respects to the two BGM-3 meters, SN 221
and SN 222, that have been deployed on Healy since 2005. Description of the meters and
34
details of data logging and processing can be found in earlier cruise reports from
HLY0503, HLY00805, HLY0806, and HLY0905, for example:
http://ccom.unh.edu/publications/Mayer_08_HEALY_0805_CRUISERPT.pdf (p. 80-83)
The meter was installed in the ship’s gravimeter compartment 615, as shown in Figures
1-21 and 1-22.
Figure 1-21. BGM-3 sensor SN 223
Figure 1-22. BGM-3 Electronics
and logging computers installed in
Louis Gravimeter Compartment #
615.
Data were logged to a dedicated laptop computer
installed with the gravimeter (shown in Fig. 1-1)
starting on July 17. Recording will continue
continuously until the vessel returns to St. John's and
the equipment demobilized. The data recorded while
the ship is dockside will be used to correct for the
long-term drift of the meter.
The data logging system records three files:
1. *.gef - raw sensor input as received by logger; new file created every hour
2. *.sde - log file reporting the status of sensor inputs
3. *.rgs - composite data file consisting of sensor input from BGM-3, vessel GPS,
and Knudsen 12 kHz bathymetry depth (Table 1-6).
The logged files files were transferred manually to the Louis shared science drive lslregulus daily during the cruise and backed up with the cruise data.
___
35
_____________________________________________________________________
1
2
3
4
5
6
RGS 2010/08/01 00:00:00.547 982591.637 25367 1280620800.547
7
8
9
10
11
12
13
14
4.99004915 856009.060 BGM3 S223 GPS: -999 -999 1280620800.547
15
16
17
18
19
20
21
22
23
-999 -999 NONE -999 -999 DEPTH: 73.450 1280620800.3220 KNUD035
24
25
26
27
28
29
HDG: 287.700 1279386502.398 NO_DNV_ERROR 1280620800.547 -999
Table 1-6 *.rgs data record; fixed length 263 characters; space delimited ASCII; 29 record fields. (Note
– need to add or replace table with description of the words in rgs string.)
________________________________________________________________________
Raw gravity readings data were filtered using a 4-minute Gaussian smoothing operator
and plotted to monitor the performance of the meter and input streams (Fig. 1-23).
Software for on-board processing and display was provided by Dr. Daniel Scheirer,
USGS, Menlo Park. Plots of on-board processing were sent back to Menlo Park regularly
for analysis, and no problems were noted. Data collected during periods when the vessel
was in open water or light ice were characterized by very well-behaved measurements.
Periods of heavy ice when Louis was being escorted by Healy were similarly smooth and
generally free of spurious noise. Only when Louis was breaking heavy ice were the data
noticeably degraded by the constant jarring and abrupt accelerations caused by contact
with ice, backing and ramming, and short-period turns (e.g. Fig. 1-23).
Preliminary data are available in a 1-minute data file containing the following 16 words
of data:
Date_Time(1) | Year(2) | DOY(3) | Lon(4) | Lat(5) | Dist_inc_1min(km,6) |
Dist_1min(km,7) | Course(deg,8) | Speed(kts,9) | Gravity_bgm223(mGal,10) |
PredGravity(mGal,11) | Eotvos Corr(mGal,12) | FAA_bgm223(mGal,13) |
Echosounder_depth(m,14) | ArcticGPv2.0_FAA(mGal,15) | IBCAO_depth(m,16)
The appendix contains preliminary (not edited or drift-corrected) daily plots of free-air
gravity anomalies, compared with the Arctic Gravity Project model (Kenyon and
Forsberg, 2008).
36
Figure 1-23. Top image shows gravity signal(blue line) with Healy breaking ice ahead of LSSL. Notice
the goodness of fit with the ArcGP grid (green line), with some finer detail added. Bottom image shows
gravity signal while LSSL breaks ice. Notice the addition high frequency noise due to accelerations of
ice contact.
Physical Oceanography
Vertical Casts
SVP, XCTD and XBT
3 Deep water Sound Velocity Probes, 33 XCTD (eXpendable Conductivity –
Temperature – Depth profiler, Tsurumi-Seiki Co., Ltd.) probes and 14 XBT (eXpendable
Bathy Thermograph) Probes were launched to measure the vertical profiles of water
sound velocity, temperature and salinity (Table 1-7 and Fig. 1-24). The three sound
velocity profiles were made to a maximum depth of 3640 m. Sound velocity and
temperature data were acquired using an Applied Microsystems SV Plus v2. With the
ship stopped, the sensor was deployed from the ship’s starboard A-frame. Measurement
accuracies from the manufacturer specifications are sound velocity: 0.05m/s with 0.03
m/s precision; temperature: 0.005ºC, pressure: 0.01% full scale (approx 0.5m). The
XBT's operated at depths to about 400 and the XCTD's to a depth of 1100 m.
37
Table 1-7 Physical Oceanographic vertical casts
Description
Lat (N)
Long (W)
SVP
SVP
SVP
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XBT t-6 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
76.60547432
81.78446433
73.69433343
72.49452942
72.80393344
73.48392518
73.68737273
73.08942998
71.86156149
72.37567827
73.21891421
73.98265644
74.75634477
75.82747286
76.3551426
78.34531618
77.36920653
78.44767927
72.80959117
76.44220963
76.58788134
75.28337329
75.73620642
76.84922247
76.16179506
76.16401291
81.78215612
76.52691438
77.39086233
81.74850222
80.48954386
76.2904055
78.19679833
78.85768809
78.99502011
79.72293589
80.88969615
81.07770128
82.44679823
82.44698137
82.18497857
81.34126666
146.4039403
128.3080373
142.4791223
149.8479296
145.3777611
145.3299964
146.0613606
147.9963329
151.4219537
151.5182689
151.0047909
150.528036
150.2065465
156.2985592
151.7013769
151.0152545
136.8824349
150.1248238
145.3781132
149.7870321
146.4722688
152.5611381
155.0069708
135.6228151
156.0590055
156.0256725
128.3377107
128.7429682
149.948386
138.5565437
123.6819825
153.1458159
152.336743
146.3820608
145.0988597
141.3447493
137.8203499
137.9498721
137.9702476
137.9667473
134.2891866
122.4675228
Time
(GMT)
17:04:17
17:05:45
20:51:46
02:59:47
00:58:09
15:15:10
02:40:04
15:16:07
14:54:30
02:52:32
15:06:42
02:49:48
14:59:32
19:51:46
19:52:18
19:42:15
23:29:50
02:52:10
01:03:48
02:49:55
14:44:44
03:04:11
14:50:27
02:54:25
03:03:35
03:10:21
16:10:41
01:26:50
02:54:24
01:38:56
16:57:27
14:53:37
15:04:47
14:45:05
18:36:06
02:54:46
17:50:14
19:33:47
14:53:21
14:57:42
00:22:24
14:42:07
Date
08/21/2010
08/27/2010
09/11/2010
08/16/2010
08/14/2010
08/14/2010
08/15/2010
08/15/2010
08/16/2010
08/17/2010
08/17/2010
08/18/2010
08/18/2010
08/19/2010
08/20/2010
08/22/2010
08/30/2010
08/23/2010
08/14/2010
08/21/2010
08/21/2010
08/19/2010
08/19/2010
09/04/2010
08/20/2010
08/20/2010
08/27/2010
09/03/2010
08/22/2010
08/26/2010
08/29/2010
08/20/2010
08/22/2010
08/23/2010
08/23/2010
08/24/2010
08/25/2010
08/25/2010
08/26/2010
08/26/2010
08/27/2010
08/28/2010
38
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-2 Cast
XCDT-2 Cast
80.98233202
78.85999037
76.72770615
76.78676639
76.14843125
75.37207312
71.28860186
71.28307866
118.9964465
135.5767434
132.2877867
133.6491919
136.1245698
136.4116547
137.0798967
137.0984348
23:43:07
14:49:56
14:52:02
19:34:14
14:48:59
02:35:49
17:50:05
18:10:08
08/28/2010
08/30/2010
09/03/2010
09/03/2010
09/04/2010
09/05/2010
08/10/2010
08/10/2010
Figure 1-24. Vertical oceanographic profile data. Black dots
are XCTD and XBT locations and the green dots are full
ocean depth Sound Velocity Probe locations.
Underway Systems:
Physical and chemical seawater measurements are taken at frequent regular intervals
throughout the cruise via seawater intake valves on the LSSL. These measurements
include salinity, temperature (inlet and lab), fluorescence, CDOM (2009-19 only), gas
tension, and oxygen saturation.
Instruments in the TSG lab were:
Seabird SBE 21 Thermosalinograph s/n 3297
Seabird SBE-38 Thermometer s/n
WET Labs WETStar fluorometer s/n WS3S-521P
WET Labs CDOM s/n WSCD-1281
39
Figures 1-25 and 1-26 show a summary of results of salinity and temperature
measurements taken through this underway system.
Figure 1-25: TSG inlet temperature
Figure 1-26: TSG salinity
Mammal Interactions and Mitigation
The full environmental assessment report for this expedition is available upon request. Of
greatest concern was interaction with marine mammals during seismic survey operations.
Appropriate mitigative measures were adopted to address this concern. These measures
40
differed for operations within the US EEZ versus areas outside of the US EEZ (Canadian
and international waters).
US EEZ regulations
Within the US EEZ, five mammal observers were required, thus two were transferred
from the Healy to the LSSL during this phase of the program. Mitigative operations
included:
1) 2 mammal observers for 30 minutes prior to start up of seismic operations. 2.5 km of
visibility was required. Maintaining a small airgun operation (power down) prevented
need for the full start up procedure during periods of repair.
2) Ramp up procedures as per normal over a 10 minute time span
3) Power down (one small pneumatic gun remain operational) vs shut down (all seismic
sources off) depending upon radius of interaction.
3) Summary of radii of interaction and appropriate action:
Spouting whales (bowhead, gray, humpback)
Powerdown at 2500 m or if behaviour changes are observed
Shutdown at 1000 m
Narwhals
Powerdown at 2500 m or if behaviour changes are observed
Shutdown at 1000 m
Beluga
Powerdown at 500 m
Shutdown at 75 m
Seals (ringed, bearded)
Powerdown at 100 m
Shutdown at 30 m
Walrus and Polar Bear
Do not approach closer
than 800 m
Canadian regulations
Bear on the ice, seemingly unfettered by passing of an
11,000 tonne ice breaker or two. (Photo Bill Schmoker)
Details of mitigative
requirements for the
CBSRRS2010 program can be seen in the Environmental Approval Application,
provided upon request of the Chief Scientist. In brief, mitigative measures follow the
guidelines laid out in the DFO Statement of Canadian Practice (http://www.dfompo.gc.ca/oceans/management-gestion/integratedmanagement-gestionintegree/seismicsismique/statement-enonce-eng.asp) and include “ramping-up” the pneumatic energy
source array and 24 hour observation for marine mammals by 3 observers to ensure no
marine mammals were within 1000 m radius of the array. If spotted within this 1000 m
radius,
41
Table 1-8. Mammal sightings
DAY
221
221
226
227
230
230
230
231
234
234
234
234
234
234
234
235
235
239
246
246
246
254
TIME
616
1711
717
945
843
1128
1356
225
1135
1154
1201
1205
1223
1328
1434
344
508
656
128
1621
1758
121
LINE #
lsl1001
lsl1003
lsl1008
lsl1010
lsl1011
lsl1011
lsl1011
lsl1012
lsl1015
lsl1015
lsl1015
lsl1015
lsl1015
lsl1015
lsl1016
lsl1016
lsl1017
lsl1019
lsl1019
lsl1024
LAT,
70.628769
70.605344
73.218959
73.35017
74.359943
74.536948
74.700054
75.258107
78.118357
78.108689
78.104431
78.102224
78.108588
78.14373
78.180155
78.477521
78.528315
81.96747
76.527392
76.747391
76.766025
73.473858
LONG.
134.528285
135.56863
145.348597
147.152028
150.275165
150.160933
150.06249
152.406534
153.309496
153.229376
153.206354
153.191607
153.103666
152.792354
152.472966
149.83533
149.381084
131.514092
128.74161
132.72258
133.191497
138.668374
MAMMAL
ring seal
ring seal
ring seal
ring seal
ring seal
ring seal
polar bear
polar bear
ring seal
ring seal
ring seal
ring seal
ring seal
ring seal
ring seal
ring seal
ring seal
ring seal
polar bear
ring seal
ring seal
polar bear
the source array was shut down
until the ship or animal
exceeded the 1000 m radius. It
should be noted that during this
and the previous four years of
seismic exploration in this
same region, no cetaceans were
seen by native observers.
During seismic operations
there were 4 polar bear
sightings and 18 seals observed
(Table 1-8; Fig. 1-27). Other
than seabirds, no other animals
were encountered.
Figure 1-27. Locations of mammal sightings.
42
Sea Ice
A daily documentary of ice
conditions is provided in
Chapter 5. This August, ice
extent was the second lowest
in the satellite record, after
2007. On September 3, ice
extent dropped below the
seasonal minimum for 2009
to become the third lowest in
the satellite record (see Figs.
1-28 and 1-29). Average ice
extent for August was 5.98
million square kilometres
(2.31 million square miles),
1.69 million square
kilometres (653,000 square
miles) below the 1979 to
Figure 1-28. Daily Arctic sea ice extent as of September 6, 2010,
2000 average, but 620,000
along with daily ice extents for years with the four lowest
square kilometres (240,000
minimum extents. The solid light blue line indicates 2010.
square miles) above the
average for August 2007, the lowest August in the satellite record. At the end of August,
ice extent had fallen to the fourth lowest in the satellite record, behind the seasonal
minima recorded for 2007, 2008, and 2009. The daily rate of decline for August was
55,000 square kilometers (21,000 square miles) per day, close to the 1979 to 2000
average of 54,000 square kilometers (21,000 square miles). (reference National Snow and
Ice Data Center: http://nsidc.org/arcticseaicenews/2010/090710.html).
Figure 1-29. 2010 Weekly ice coverage, Southern Canada Basin
43
Aerial photograph showing ice conditions, taken during the expedition from the
helicopter. Photo by Bruno Barrette
As a result of these conditions, combined with the fact that winds were light for the
majority of the expedition. Sea ice conditions were favourable for two-ship seismic
operations, and even single ship operations in southern extremities. The pack did not
extend as far south this year as it did last, permitting single ship operations in this area
(see Fig. 1-30).
Significant flows of second and multiyear ice were encountered, but in general there were
significant open water polynas indicating no ice pressure. Significant ice cover and
thicknesses were not experienced except in the northern region of the study area. On line
17, for example, ice breaking became difficult and ridges were encountered that required
several attempts to break through. By the easternmost extent of the line, north of Sever
Spur, where a tie was made to a spot sounding line from the 2010 spring program, ice
was heaviest. During the following med-evac, our route took us across Sever Spur from
north to south. Initial ice breaking was heavy and the two ice breakers worked in tandem.
By the southern half of Sever Spur, however, conditions lightened somewhat and open
water was observed. This is remarkable, given the difficulty in attempts to acquire data
here in 2008. Heavy ice breaking was again required off of McClure Strait during transit
to meet up with the Healy and commence Line 19.
44
Figure 1-30. Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E)
images: Top is August 5, 2010 and bottom September 7, 2010, showing differences in ice edge
positions and approximate percent ice cover, as interpreted from the imagery data. The white
boxes outline our survey area.
Weather
Weather conditions were typical of the Beaufort Sea summer season. For a month and a
half, Beaufort Sea was under the influence of a stationary high pressure system in
anticyclonic flow, with two exceptions: On August 30th and on September 9th, a trough
45
line of low pressure brushed the SW portion of Beaufort Sea which brought decks of
clouds at higher altitudes.
This anticyclone drifted with upper levels circulation from west to east and back
regularly but never by more than a few hundred NM. This anticyclone signifies that the
colder air (cooled by the presence of the ice pack) is trapped under an inversion. With
moisture from the surrounding open water and generally light winds, extensive fog
resulted from surface to a few hundred feet upward. The result was 25 days of fog,
reducing visibility between less than one-half nautical mile and 6 nautical miles.
Intermittently, when conditions were favorable, the fog dissipated somewhat from midafternoon to early evening. That was when there was enough warming in the lower levels
to “burn” the fog from the top down or when the wind was strong enough to lift the foggy
layer up a few hundred feet into a stratus layer. The sun shined on only six days on the
17th and 18th of August, on the 22nd and 23rd of August and on the 8th and 9th of
September.
Light winds (15K or less) characterised the dominant wind patterns, with a few
exceptions: on our transit to Beaufort Sea, winds blew first from the SE at 20K on August
6th and then from the NE at 20-25K with gusts up to 35K on August 7th and 8th. The
wind attained gale force on the 8th generating significant waves and swell (up to 4.5
metres). Strong winds occurred again on August 15th, with easterlies at 25 to 30 knots
due to a trough line on the Alaskan North Slope shoreline pushing and tightening the
western high pressure-gradient. The same phenomenon repeated itself on the 7th and 8th
of September when winds blew from the SE at 25K with gusts up to 35K. There was a
steady northwesterly flow at 25 knots in Dolphin and Union Strait during a return transit.
Circulation was forced by a low pressure system that developed over Victoria Island and
slowly drifted SSE to be 120 NM east of Kugluktuk on the 15th. This brought strong
colder northerlies to the region along with rain and snow.
Temperatures remained in a range such that daily minima were near -4C and the daily
maxima near +4C. The maximum temperature registered in Beaufort Sea was +7.8C on
September 7th, when the southerly flow described above brought milder air to the region.
The minimum temperature was -5C recorded on September 5th, near 75N and 135W.
Recommendations
 Compressor failures remain an issue, requiring significant maintenance and repair
and constant watchkeeping during operation. Experienced staff must be
employed for this purpose
 The working environment within the compressor container is extremely
uncomfortable. Wind chill is a real issue and concern. As well, the
operator/watchkeeper is exposed to the working parts of the compressor, posing a
risk during operation. A cabin or enclosed space within the compressor container
needs to be constructed for comfort and safety reasons.
 A hazard / general alarm light needs to be installed within the compressor
containers.
46








Sounder/Chirp: the hull mounted sounder did not perform well in ice conditions.
Can we carry a towed instrument? No doubt it would increase launch and
recovery time, which would not be ideal.
Staffing: we must carry some younger staff for job-shadowing to ensure crossover in skills and knowledge.
Replace hard drives on seismic digital acquisition and firing units. Carry spares.
Re-evaluate the design of the source array. The cluster of 2x500 in3 G guns plus
1x150 in3 G gun was chosen in previous surveys to limit stresses on the tow sled
from firing of the airguns. However the current arrangement for mounting the
airguns appears to be robust and it seems possible to revise the number and types
of airguns in the cluster. The number could be increased to four using the existing
mounts on the tow sled, and perhaps GI-guns could be added in some positions to
improve the primary-to-bubble pulse ratio.
The installation of the SeaStar CTD sensors in floats near receiver groups 1, 9,
and 16 provided useful depth, temperature, and salinity data that could be used for
rebalancing the streamer. Even if the streamer is not rebalanced, the CTDs are
useful tools that should be used next season to monitor the streamer depths. The
service life of the existing set should be checked, and an additional three CTDs
should be purchased as spares and also for rapid deployment on the second
streamer.
Before the start of acquisition next season, the depth calibration of each CTD
should be checked by placing the sensors in a permeable container and lowering
the package to a known water depth.
A few months prior to the seismic program, obtain the latest version of the CNT-2
acquisition software and manuals, install two copies of the software on removable
hard drives, and create an installation backup. The new software should be tested
prior to the start of acquisition. Version 5.36 proved to be reliable and should
therefore be kept as a backup in case there are bugs in a later version of the
software.
Replace the computer hard disks on the seismic data recorder before the next field
season in case there has been sector damage due to the vibration of ice-breaking.
Bring spare Hard Drives in case of failure.
Acknowledgements:
The scientific party wishes to thank Captain McNeill and the Officers and Crew of the
Canadian Coast Guard Ship Louis S. St-Laurent. Additionally, the Scientific Party would
like to express its appreciation to the ice-breaking efforts of the US Coast Guard Cutter
HEALY and its Commanding Officer, Capt. William Rall and his Officers, Crew and the
Scientific Staff of expedition HLY1002. Their assistance went well above and beyond
ice breaking in an effort to ensure success of this mission.
The authors would like to express our highest appreciation, respect and admiration for the
technical crew of the scientific party. The program would definitely have not achieved
success without the long hours of commitment and their innovative solutions to unique
problems that arise from working in the harsh environment of the Arctic.
47
Mr. Jamison Etter, Mechanical trainee, air gun maintenance and repair
Mr. Jim Etter: Hydraulics, electronics and watch keeping
Mr. Paul Girouard: Navigation, network, and data curation
Mr. Rodger Oulton: Compressor and diesel mechanical and watch keeping
Mr. Dwight Reimer: GeoEel system, air gun control and watch keeping
Mr. Ryan Pike: Inventory control, air gun mechanical, watch keeping
Mr. Nelson Ruben: Compressor watch keeper
Mr. Peter Vass: Machinery fabrication and equipment maintenance
And of course, our Mammal Observers, for endlessly keeping watch in the frigid and
inhuman climatic conditions on Monkey’s Island: Jonah Nakimayak, John Ruben and
Dale Ruben. Kevin DesRoches has our gratitude for reviewing this lengthy manuscript.
References:
Grantz, A., Hart, P.E. and May, S.D., 2004. Seismic reflection and refraction data
acquired in Canada Basin, Northwind Ridge and Northwind Basin, Arctic Ocean in 1988,
1992 and 1993. U.S. Geological Survey Open-File Report 2004-1243. Online
http://pubs.usgs.gov/of/2004/1243/index.html. Accessed January 7, 2011.
Kenyon, S.C. and R. Forsberg, 2008, New Gravity Field for the Arctic, EOS, 89, p. 289
Mosher, D.C., Shimeld, J.D. and Hutchinson, D.R., 2009. 2009 Canada Basin seismic
reflection and refraction survey, western Arctic Ocean: CCGS Louis S. St-Laurent
expedition report, Open File 6343, 266 p.
48
Chapter 2: Acquisition and Processing of the Seismic
Reflection Data
John Shimeld
Introduction:
Seismic operations were conducted between August 8th and September 11th with
interruptions for equipment repairs, transits between lines, and two medical evacuations.
A total of 3763.3 line km of 16-channel, short-offset, 2D seismic reflection data were
acquired during the cruise. The seismic profiles extend across continental shelf,
continental slope, and abyssal plain regions of Canada Basin, Northwind Ridge, and
Alpha Ridge in the Arctic Ocean (Figure 2-31). Water depths ranged from a minimum of
58 m across portions of the Beaufort shelf, to a maximum of 3898 m over central Canada
Basin. Start and end points of each line are summarized in Table 2-8.
The survey was conducted under a wide range of sea conditions including calm open
water, rough open water with 3–4 m swells and, for roughly 50% of the surveyed
distance, within the perennially frozen Arctic icepack. Across most of this region there
was 6 to 9 tenths first year ice cover ; pans of multiyear ice rarely comprised more than 4
tenths of the total. Ice ridges were sparse except along portions of LSL1017 and
LSL1018 where ridges up to about 1.5 m in height were encountered. Winds were light
to moderate, rarely exceeding 25 knots, and the ice was not under significant
compression during the seismic operations. From preliminary satellite record analyses,
the U.S. National Ice Centre reports that the areal extent of the summer icepack this year
was the third smallest on record since the beginning of satellite imagery in the late 1970s.
Relative to previous field seasons, the general ice conditions this season were noticeably
lighter and, accordingly, there is significantly less ambient noise on the seismic records
from icebreaking operations.
Seismic profiles were collected along lines that were planned in advance of the program.
However, as anticipated, variable ice conditions and operational constraints caused the
shiptrack to deviate, sometimes significantly, from the original plan. The bridge crew of
both vessels worked together to plot and maintain the straightest possible course through
the ice within ±5 nautical miles of planned lines, although some exceptions were
unavoidable. To save time and to cover the maximum survey distance possible, no
overlaps between lines were made. Transitions between lines were made with simple
turns using a radius of ½ nautical mile or greater. The seismic lines are named LSL1001
through LSL1025. New lines were started at each redeployment of the gear and also at
significant changes in line heading.
49
Figure 2- 31. Location map of the survey area. In total, 3763.3 line km of 16-channel, short-offset seismic data
were acquired during the Louis S. St-Laurent 2010 cruise. The seismic lines are shown in black. The start of
each line is numbered and indicated with a white dot. Pre-existing seismic data are plotted with thin white lines.
50
Table 2-8: Shot and trace statistics for seismic reflection line segments collected during
this cruise.
Line
First
Shot
Last
Shot
# of Traces
(actual/nom.)
Start
Coord.
End
Coord.
Average
Shotpoint
Bathymetric
Line km Spacing (m) Range (m)
Start Date
(UTC)
End Date
(UTC)
LSL1001 1
4380
68480/68480
71.181437,
-135.711082
70.490628,
-134.306715
96.1
21.9
59
1096
20:13:40
08/08/2010
08:26:40
09/08/2010
LSL1002 4381
5995
25840/25840
70.489834,
-134.306112
70.356261,
-135.147182
36.2
22.4
55
73
08:27:20
09/08/2010
12:56:20
09/08/2010
LSL1003 5996
10767
76352/76352
70.356314,
-135.162049
71.191241,
-136.606276
108.6
22.8
58
1331
13:00:30
09/08/2010
02:15:40
10/08/2010
LSL1004 10768
12951
34944/34944
71.192268,
-136.609363
70.984560,
-137.779364
49.1
22.5
1301
1609
02:16:50
10/08/2010
08:20:40
10/08/2010
LS1005
12952
15548
41552/41552
70.984013,
-137.782076
71.313990,
-136.993008
51.9
20.0
1466
1612
08:21:30
10/08/2010
15:35:00
10/08/2010
LS1006
15549
18853
52880/52880
71.649670,
-148.182597
72.264513,
-145.408145
119.1
36.0
2864
3562
22:55:02
12/08/2010
14:20:10
13/08/2010
LSL1007 18854
20509
26496/26496
72.265346,
-145.406365
72.794077,
-145.378622
59.4
35.9
3472
3585
14:21:01
13/08/2010
22:09:55
13/08/2010
LSL1008 20510
22709
35200/35200
72.775034,
-145.370076
73.428322,
-145.342553
75.6
34.4
3560
3705
00:08:04
14/08/2010
10:53:03
14/08/2010
LSL1009 22710
24090
22096/22096
73.423545,
-145.331658
73.917445,
-145.303738
56.1
40.6
3661
3778
14:16:11
14/08/2010
21:44:41
14/08/2010
LSL1010 24091
31809
123504/123504
73.922324,
-145.31806
71.885529,
-151.372006
308.1
39.9
2489
3785
21:49:53
14/08/2010
14:30:25
16/08/2010
LSL1011 31810
40513
139264/139264
71.804533,
-151.725993
74.725078,
-150.047607
333.7
38.3
1774
3893
18:11:18
16/08/2010
14:17:20
18/08/2010
LSL1012 40514
46023
88160/88160
74.727155,
-150.050525
75.823048,
-156.190547
222.1
40.3
1516
3898
14:19:17
18/08/2010
19:34:08
19/08/2010
LSL1013 46024
47818
28720/28720
76.175691,
-156.211394
76.249155,
-154.104978
58.3
32.5
875
3894
01:39:03
20/08/2010
09:43:24
20/08/2010
LSL1014 47819
53039
83536/83536
76.242675,
-154.15410
76.589597,
-146.403825
210.2
40.3
3834
3896
10:52:18
20/08/2010
15:08:48
21/08/2010
LSL1015 53040
55102
32976/33008
78.113765,
-153.272554
78.392021,
-150.795565
68.8
33.3
2076
3882
11:43:49
22/08/2010
22:20:45
22/08/2010
LSL1016 55103
58293
51056/51056
78.382297,
-150.721739
78.992636,
-145.119424
140.7
44.1
3860
3883
00:52:32
23/08/2010
18:31:03
23/08/2010
LSL1017 58294
63759
81792/87456
82.546172,
-138.948401
81.761080,
-128.626175
188.3
34.4
3354
3728
11:37:28
26/08/2010
13:33:46
27/08/2010
LSL1018 63814
64270
7312/7312
81.788899,
-128.225476
81.722137
-127.304905
17.4
38.1
3564
3620
19:34:24
27/08/2010
21:43:35
27/08/2010
LSL1019 64318
70233
94656/94656
76.539330,
-128.747008
76.861302,
-136.025837
191.4
32.3
2159
3679
01:52:10
03/09/2010
04:15:15
04/09/2010
LSL1020 70234
74696
71408/71408
76.858814,
-136.051187
75.374560,
-136.415813
170.6
38.2
3565
3679
04:21:12
04/09/2010
02:29:33
05/09/2010
51
LSL1021 74697
84731
160560/160560
75.361204,
-136.419908
72.425185,
-136.988291
347.4
34.6
2574
3595
03:11:51
05/09/2010
01:10:10
07/09/2010
LSL1022 84732
90176
87120/87120
72.421465,
-136.990578
70.997368,
-137.604067
162.9
29.9
1460
2573
01:14:31
07/09/2010
23:10:09
07/09/2010
LSL1023 0
97493
117072/117072
70.992837,
-137.603924
71.495977,
-131.493389
226.9
31.0
517
1550
23:14:59
07/09/2010
04:43:01
09/09/2010
LSL1024 97494
109683
195040/195040
71.505001,
-131.491848
73.847738,
-140.345755
395.4
32.4
684
3548
04:49:47
09/09/2010
10:18:24
11/09/2010
LSL1025 109684 111470
28592/28592
73.848794,
-140.352026
73.700255,
-142.488482
69.0
38.6
3547
3671
10:20:12
11/09/2010
19:16:00
11/09/2010
Source Parameters
Airgun Configuration and Firing Delays
A cluster of 3 Sercel G-guns comprised the seismic source for this survey (c.f. Chapter
1). Two of the airguns each had a volume of 500 in³, and the third a volume of 150 in³,
so the total volume of the seismic source was 1150 in³.
As described in Chapter 1, two different towing arrangements were used. In open water,
the airgun cluster was suspended from a float at a depth of 5.5 m and towed 50 m aft of
the stern roller sheave. In the icepack, the cluster was attached to a weighted sled
suspended immediately below the stern roller sheave at a depth of 11.2 m.
The three airguns were fired simultaneously with a field time break of 46 ms. There was
an additional mechanical delay of 10 ms, measured using an oscilloscope. Thus the total
delay between time zero of the shot records and actual firing of the airguns was 56 ms.
Shot Interval
The source was fired at regular time intervals chosen in relation to the water depth as
follows :
 10 s for < 3 s of water ;

14 s for 3–4 s ;

17 s for 4.0–4.8 s ;

18 s for 4.8–5.0 s ; and

19.5 s for > 5 s.
The distance between shotpoints varied during the survey as a function of these shot
intervals and also the vessel speed over the ground, which fluctuated especially during
periods of heavy icebreaking. The bridge crew tried to maintain an average speed over
the ground of 4.0–4.5 knots and a speed through the water of no greater than 5.5 knots.
At a 19.5 s shot interval, the distance between shots was ≤44 m, and at a 14.5 s shot
interval the distance between shots was ≤23 m. The average over the entire survey was
33 m.
52
Source Wavelet
As described in Chapter 4, far-field recordings of the source were made for the openwater towing configuration during August 10th, and for the icepack towing configuration
during September 4th. Average source wavelets were derived by aligning and stacking
traces from shot records of each airgun combination. These are plotted on Figures 2-32
through 2-35.
The power spectra of the G-guns, in both the open-water and icepack towing
configurations, manifest serious notches across a number of frequency ranges within the
practical seismic bandwidth of roughly 3 to 70 Hz (Figures 2-33 and 2-35). These
notches are caused by destructive interference between the primary and the bubble pulses
and they have a significant negative impact on both the depth of penetration and
resolution of the seismic data. Although the spectra are not calibrated, it appears that the
150 in3 G-gun adds power that partially offsets the low-frequency notches (e.g. at 10 and
20 Hz), but it does not add significantly to the upper frequencies of the seismic
bandwidth.
With the airguns at 5.5 m in the open-water towing configuration, destructive interference
between the primary and source ghost should create a distinct notch at about 131 Hz.
However the power spectra diminish rapidly above 70 Hz (Figure 2-33) and there is
surprising little power in the 70 to 125 Hz band. This does not significantly impact the
primary objective of imaging the base of sediments, but it does reduce the vertical
resolution that can be achieved for shallow targets.
With the airguns at 11.2 m in the icepack towing configuration, the source notch should
be apparent at about 64 Hz, and significant drop in power does occur at that frequency
(Figure 2-35). However, the 1150 in3 spectrum exhibits power above 64 Hz that is not
apparent for the other source volumes. This suggests that the calibrated measurements of
the 1150 in3 source might be contaminated with high frequency noise although it was not
noted during the measurements.
Power spectra of the raw data show obvious similarities with the calibrated source
measurements including the strong bubble pulse notches (Figure 2-36). The practical
seismic bandwidth of data acquired with the open-water towing configuration is
comparable to that of the calibrated source measurement. This is because the receiver
depths are generally equal to or shallower than the source depth so the receiver ghost
suppresses power in frequency bands at or above the source ghost notch (Figure 36A).
However, during icebreaking the receiver depths frequently exceed the source depth.
Often the receiver ghost notch occurs between about 30 and 60 Hz (Figure 36B), and can
sometimes suppress frequencies in the 20 Hz range.
53
Figure 2-32: Source wavelets for the open-water towing configuration (source depth = 5.5 m). The time series
were derived by aligning and stacking the traces recorded for various G-gun combinations during the August
10th calibrated hydrophone measurements (cf. Chapter 4). Total source volumes are as follows : A) 150 in3 ;
B) 500 in3 ; C) 650 in3 ; D) 1000 in3 ; E) 1150 in3.
54
Figure 2-33: Relative power spectra for the open-water towing configuration (source depth = 5.5 m). The
various G-gun combinations were recorded during the August 10th calibrated hydrophone measurements (cf.
Chapter 4). Total source volumes are as follows : A) 150 in3 ; B) 500 in3 ; C) 650 in3 ; D) 1000 in3 ; E) 1150
in3.
55
Figure 2-34: Source wavelets for the icepack towing configuration (source depth = 11.2 m). The time series
were derived by aligning and stacking the traces recorded for various G-gun combinations during the
September 4th calibrated hydrophone measurements (cf. Chapter 3). Total source volumes are as follows : A)
150 in3 ; B) 500 in3 ; C) 1000 in3 ; D) 1150 in3.
56
Figure 2-35: Relative power spectra for the icepack towing configuration (source depth = 5.5 m). The various
G-gun combinations were recorded during the September 4th calibrated hydrophone measurements (cf.
Chapter XX). Total source volumes are as follows : A) 150 in3 ; B) 500 in3 ; C) 1000 in3 ; D) 1150 in3.
57
Figure 2-36: Relative power spectra for samples of the unprocessed data. Traces within each shot record
were stacked and then sets of 5 adjacent shots were summed. The power spectra were computed over a 6.5 s
window for A) LSL1001, representing the open-water towing configuration with the 1150 in3 source, and B)
LSL1011 which was acquired with the icepack towing configuration with the 1150 in3 source. Receiver
depths for LSL1011 ranged between 14 and 21 m in this example, which noticeably suppresses power in the
35 to 50 Hz band.
58
Receiver Parameters
The receiver array consisted of two active sections, each 50 m long, with 64 equally
spaced hydrophones. These were configured into 8 channels per active section with 8
hydrophones per group. Accordingly, there were a total of 16 active channels with a
group interval of 6.25 m.
Icebreaking operations lead to frequent course deviations, changes in speed, and even
complete stops. Also there can be significant water temperature and salinity changes
around the icepack, meaning that correct balancing of the streamer is not possible over
the duration of the survey. Active control of the streamer is not feasible because of the
risk of damage or loss should a streamer bird become caught in the ice. As a result of
these factors, receiver depths can vary significantly along the length of the streamer and
also from one shot to the next. Differences of several metres between the inboard and
outboard receiver groups are common, and the average depth along the streamer can
change by 20 m in the space of 10 minutes when the ship encounters difficult patches of
ice.
Receiver depths were measured in two ways : 1) with ODDI SeaStar mini-CTD sensors
installed in wooden floats near receiver groups 1, 9, and 16 as was done during the 2009
program (Mosher et al, 2009); and 2) using pressure transducers that are built into the
GeoEel streamer at receiver groups 1 and 16. The SeaStar CTDs were programmed to
measure depth, temperature, and salinity at 10 s intervals and the data were downloaded
after each gear recovery. These CTDs were used whenever possible since they are
considered more accurate than the GeoEel depth sensors, and also because the GeoEel
sensors in the starboard streamer were inoperative for the duration of the survey.
Comparison of the depths reported by the SeaStar and GeoEel sensors reveals systematic
errors in the GeoEel sensors which were corrected during data processing using the linear
regression equations shown on Figure 2-37.
Fluctuations in receiver depth change the way in which energy reflected downwards from
the sea surface (the receiver ghost) interacts with upward travelling energy and can
effectively suppress a broad range of frequencies between about 30 and 60 Hz. The
fluctuations can also cause travel time shifts of 20 ms or more, leading to inaccuracies in
the seismic datum and misties between intersecting lines. These issues can be largely
corrected using traces shifts and source signature deconvolution if the receiver depths are
known with reasonable accuracy.
59
Figure 2-37: Comparison of receiver depth measurements obtained using the ODDI SeaStar mini-CTD sensors
with the GeoEel depth sensors on A) channel 1, and B) channel 16. For the seismic data processing, measurements
from the GeoEel sensors were corrected to more closely match those of the SeaStar sensors by applying the linear
regression equations shown on the figure.
60
Source-to-Receiver Offsets
The Novatel Global Positioning Satellite (GPS) antenna located above the wheelhouse
top at frame 198 of the ship was used as the fixed navigation point for the survey. The
source and receiver offsets relative to the fixed navigation point are shown on Figure 238 for the open-water and also the icepack towing configurations.
Figure 2-38: Source to receiver offsets for A) the open-water towing configuration and B) the icepack towing
configuration. All distances are in metres.
61
Data Recording
CNT-2 Software Parameters
The seismic reflection data were recorded using the Geometrics GeoEel system described
in Chapter XX. With this system, analog hydrophone signals are converted to 24-bit
digital traces by analog-to-digital converters in the streamer and are automatically
summed for each receiver group. The trace data from each receiver group are broadcast,
via ethernet connection in the streamer, to the multithreaded CNT-2 software (version
5.36) running under the Windows NT operating system on a personal computer in the
seismic lab.
The CNT-2 software provides a user interface for configuring the GeoEel system, for
monitoring the data quality during acquisition, for testing the receiver array, and for
recording the data to magnetic disk drive and/or magnetic tape. Additional data such as
geographic position or source signature information can also be logged by the CNT-2
software through a serial communications port. The recording parameters that were used
during the survey are listed in Table 2-9.
Table 2-9: Recording parameters used with the Geometrics CNT-2 software during the
survey.
Parameter
Value
Sample interval
2 ms
Recording window
LSL1001 through LSL1005 :8.0 s
All other lines : 12.0 s
Recording delay
LSL1001 through LSL1005 : none
All other lines : 0.5 s
Recording format
SEG-D 8058 revision 1
Active channels
1 through 16
(near trace = 1; far trace = 16)
AC coupling
disabled
Shot/file number comparison
disabled
Preamp gains
+18 dB on all channels
Transconductance
20 Volt/bar
Data Storage
Digital shot records were stored on magnetic disk drive, one file per shot record, in the
Society of Exploration Geophysicists SEG-D 8058 Revision 1 format. Included in each
SEG-D file is an variable-sized external header containing GPS navigation strings
including date (UTC), geographic position in degrees and decimal minutes (reference
62
ellipsoid: World Geodetic System, 1984), water depth from the 12 kHz sounder, speed
through the water, heading, speed over ground, and course over ground.
The SEG-D files were copied every half-hour onto a separate magnetic disk drive
installed on the recording computer. Upon completion of each line, all associated shot
records and log files were copied onto two additional hard drives and a set of DVDs for
archival.
Figure 2-39: Screen capture of the CNT-2 graphical user interface showing a message log (top left), RMS noise
chart (top middle), shot record (bottom left), and brute stack (right). The software also allows the frequency
spectra of each trace to be monitored (not shown).
Data Quality Monitoring and Seismic Watchkeeping
During acquisition the CNT-2 user interface was used to automatically plot each shot
record, the amplitude spectra of each trace, a log of diagnostic messages, and a simple
brute-stack record section. An example monitor display is shown on Figure 2-39. This
provided immediate, shot-by-shot feedback on the GeoEel system performance and
confirmation that the data were of acceptable quality. The software is capable of
displaying a bar graph of root-mean-squared (RMS) noise levels within a user-defined
window for each shot record, but this function appeared to cause the software to crash
and so this function was abandoned.
Watchkeepers kept a half-hourly log of the following system parameters: calendar day,
UTC time, latitude, longitude, line segment, water depth, course over ground, heading,
speed over ground, speed through water, ship's bubbler (on/off), streamer system
(port/starboard), streamer leakage, streamer current, streamer voltage, streamer depth
(inboard/outboard), seismic source system (port/starboard/tow depth), shot number, total
source volume, number of airguns, firing rate, record length and recording delay. An
electronic copy of the watchkeepers' log is included with the cruise documentation.
63
Data Processing
The Globe Claritas commercial software package (version 5.4) developed by the New
Zealand Institute of Geological and Nuclear Sciences was used to process the seismic
data during the cruise. The software was installed on a dual-processor laptop running
the Fedora Linux operating system (release 11). An external 500 gigabyte, universal
serial bus hard-drive was used to store copies of the raw and processed datasets. The
processing workflow is listed below, and a summary of CMP range, shot range, fold, and
line length is given in Table 2-10.
Processing Workflow
1. Read SEG-D
Read individual shot records in SEG-D format ; apply static shifts to account for
recording delay (+500ms), field time break (-46 ms), and firing delay (-10 ms).
2. Navigation and Geometry
Extract navigation information from SEG-D trace headers, including : longitude,
latitude, water depth, speed through water, speed over ground, and date ; design
CMP bins at 12.5m intervals along track assuming streamer directly behind
vessel.
3. Receiver Depths
Interpolate the depth of each receiver group at each shotpoint by matching shot
times with a 30 s (3-point) average of depth measurements from the ODDI
SeaStar mini-CTDs. When these measurements are unavailable, interpolate the
receiver depths using corrected measurements from the GeoEel depth sensors (c.f.
Figure 2-37). Apply source/receiver static corrections to each trace using a
surface water velocity of 1440 m/s to shift each trace to sea level datum.
Receiver depths range between 0.1 and 63.9 m, with an average of 10.7 m for the
entire survey. The depth at channel 1 is typically 1−3 m shallower than at channel
16, but this varies as a function of speed through the water and also the water
column properties. Static corrections for the average source and receiver depths
range between 3 and 52 ms.
4. Swell Noise, Strumming, and Geometrical Spreading
Bandpass filter (3/8/140/240 Hz) ; F-K filter (>4ms per trace) ; T2 amplitude
scaling ; balance.
5. Trace Editing
edit erroneous traces ; calculate integrated instantaneous frequency 0−5 s
beneath seafloor to identify noisy traces ; low-cut filter (8/12 Hz) applied to
noisiest 5% of all traces in the survey ; low-cut filter (10/14 Hz) applied to
noisiest 1% of all traces in the survey ; balance.
Since there is no opportunity for data re-acquisition, it is desirable to retain even
very noisy traces in the processing stream unless they truly contain no usable
signal. During icebreaking operations the noise can vary significantly from
channel to channel, but manual editing of every shot record would be timeconsuming and highly subjective. To characterize the noise efficiently, and in a
64
quantitative manner, instantaneous frequency was integrated over a 5 s window
beneath the seafloor. Traces with high noise levels from swell, cable strum, and
propwash have abnormally low values of integrated instantaneous frequency and
can be reliably identified using this attribute. Thresholds of 5% and 1% were
chosen for low-cut filtering.
6. Minimum Phase Conversion, Source Signature Deconvolution, and CMP
Stack
minimum phase conversion ; source signature deconvolution ; gapped
deconvolution (300 ms, gap at 2nd zero crossing); sort traces to CMP gathers ;
calculate CMP static shifts (≤ 8 ms) to maximize stacking power ; balance ; stack.
A matching filter designed on the measured source wavelet was applied to convert
the data to minimum phase. To include the effects of the receiver ghost, the
source signature was convolved with two spikes : +1.0 at time-zero and -0.7 at
the calculated travel time to the interpolated receiver depth of each trace.
Suppression of the bubble pulse was achieved with prestack gapped
deconvolution using the 2nd zero crossing of each trace as the gap length.
7. Primary Multiple Suppression
A forward model of the seismic record was constructed by convolving the source
wavelet with the deconvolved stack obtained in step 6 (after removal of NMO
corrections). The resulting traces were then autoconvolved to generate an
estimate of the first primary multiples. These were removed from the
deconvolved stack of step 6 using the adaptive subtraction routine described by
Monk (“Wave-equation multiple suppression using constrained grossequalization” in Geophysical Prospecting, v. 41, p. 725−736, 1993). Poststack FK filtering was applied to further suppress energy parallel to the first seafloor
multiple.
8. 2-D Velocity Models
The following linear model of sediment velocity was derived from analyses of the
2007−2009 sonobuoy records : V(t) = 2067 + 727*t, where t is the one-way travel
time beneath the seafloor. A constant average velocity of 1480 m/s was used for
the water column.
9. Poststack Filtering
despike ; balance ; gapped deconvolution (800/80 ms, 51 trace mix) ; F-X running
mix coherency filter (5 traces) ; finite difference migration using velocity model
derived in step 8 (0.95*V(t)) ; singular value decomposition coherency filter ;
linear amplitude scaling (5 dB/s beneath seafloor) ; phase shift (270˚) ; timevarying lowpass filter (60/80 Hz at 0−2 s below seafloor, 30/40 Hz at 2.5−3.5 s,
25/35 Hz at >4 s) ; 5 trace running mix (weighted at 0.05, 0.2, 0.5, 0.2, and 0.05).
10.
SEG-Y Output
insert missing CMPs ; interpolate shotpoints ; antialias filter; resample (4 ms) ;
SEG-Y output with CMP latitude/longitude as arcsec (x100) in byte locations 81
and 85.
65
Table 2-10: Summary of deconvolved CMP stacks derived from the 16-channel,
short-offset seismic data acquired during the Louis S. St-Laurent 2010 program.
Average
Line First CMP Last CMP First Shot Last Shot CMP fold
Line km
001
114
7740
4372
65
18
95.3
002
114
3016
5987
4381
18
36.3
003
100
8792
5996
10760
17
108.7
004
114
4049
12944
10768
18
49.2
005
100
4262
12952
15540
19
52.0
006
100
9638
15549
18849
12
119.2
007
100
4860
18854
20505
12
59.5
008
100
6166
20510
22688
12
75.8
009
100
4590
22710
24087
10
56.1
010
112
24744
31804
24091
8
307.9
011
100
26826
31810
40509
8
334.1
012
100
17912
40514
46018
8
222.7
013
100
4772
46024
47813
13
58.4
014
100
16778
47864
53028
11
208.5
015
100
5619
53040
55089
11
69.0
016
100
11355
55103
58288
8
140.7
017
100
15116
58294
63754
8
187.7
018
100
1502
63814
64261
10
17.5
019
112
0
0
64318
13
191.9
020
112
13761
74688
0
12
107.6
021
112
27826
84726
0
12
346.4
022
112
13148
0
84732
14
163.0
023
0
18253
0
0
13
226.9
024
0
31761
97494
0
13
395.8
025
112
5645
111462
0
10
69.2
Comments
1. LSL1001 through LSL1005
The ODDI SeaStar mini-CTDs were not installed on the streamer during acquisition of
these lines. Receiver depths were obtained by applying the corrections shown on Figure
2-37 to the GeoEel depths sensors at channels 1 and 16. Depths for the remaining
channels were linearly interpolated.
2. LSL1009
66
The ODDI SeaStar mini-CTD was inadvertently not installed at receiver group 16 during
deployment of the starboard streamer for this line. Since the GeoEel depth sensors are
not functional for the starboard streamer, no receiver depth measurements are available
for channel 16. Therefore, for processing, the depths for channels 10 through 16 were
assigned the same depths as were measured for channel 9.
3. LSL1010
Swells of up to 3 m increased noise levels along this line between shotpoints 30000 and
31809.
4. LSL1015 and LSL1017
Recording errors occurred for a number of shot records on these lines. The Geometrics
software reported problems and timeouts with serial and ethernet communications and
this caused SEG-D files to be written with only channels 9–16. The problems were found
to be caused by damaged cables in the bundle cable.
5. LSL1019
This line is contaminated by primary multiple energy from strong reflectors in the upper
sedimentary sequence, including the seafloor.
6. LSL1022 and LSL1023
Swell noise was high along these lines because of 25-30 knot ENE winds over open
waters which created waves in excess of 3 m.
67
Recommendations
1. An accurate description needs to be obtained from Geometrics regarding the
amplitude and phase characteristics of the analog 3 Hz low-cut filter that is
implemented by AC coupling of the streamer. Application of a pre-digitization
analog filter is desirable since it greatly expands the dynamic range of the
recorded signal, but our tests indicated that AC coupling negatively affects signal
across the 1-20 Hz band.
2. Re-evaluate the design of the source array. The cluster of 2x500 in3 G-guns plus
1x150 in3 G gun was chosen in previous surveys to limit stresses on the tow sled
from firing of the airguns. However the current arrangement for mounting the
airguns appears to be robust and it seems possible to revise the number and types
of airguns in the cluster. The number could be increased to four using the existing
mounts on the tow sled, and perhaps GI-guns could be added in some positions to
improve the primary-to-bubble pulse ratio.
3. The installation of the SeaStar CTD sensors in floats near receiver groups 1, 9,
and 16 provided useful depth, temperature, and salinity data that could be used for
rebalancing the streamer. Even if the streamer is not rebalanced, the CTDs are
useful tools that should be used next season to monitor the streamer depths. The
service life of the existing set should be checked, and an additional three CTDs
should be purchased as spares and also for rapid deployment on the second
streamer.
4. Before the start of acquisition next season, the depth calibration of each CTD
should be checked by placing the sensors in a permeable container and lowering
the package to a known water depth.
5. A few months prior to the seismic program, obtain the latest version of the CNT-2
acquisition software and manuals, install two copies of the software on removable
hard drives, and create an installation backup. The new software should be tested
prior to the start of acquisition. Version 5.36 proved to be reliable and should
therefore be kept as a backup in case there are bugs in a later version of the
software.
6. Replace the computer hard disks on the seismic data recorder before the next field
season in case there has been sector damage due to the vibration of ice-breaking.
68
Chapter 3: Canada Basin 2010 Canadian Hydrographic
Service
Jon Biggar, CHS
69
Background
The Canadian Hydrographic Service (CHS) is responsible for a number of conditions
under Article 76 of the United Nations Convention on the Law of the Sea (UNCLOS)
to delineate/survey/establish the continental shelf for Canada’s territorial submission:
 mapping baselines from which the extent of the territorial sea is measured;
 mapping the 2500 metre isobath and the Foot of the Slope;
 Optimising the location of boundary lines at calculated distances. (60, 100, 200
and 350 nautical miles);
 Populating data bases with the above data and outputting in the form of charts,
maps and diagrams
Summary
As in the past four years of this program the CHS component was conducted in
conjunction with the NRCan seismic operations. The program again was successful. The
program involved two icebreakers: the CCGS Louis S St Laurent (Canada) and USCGC
Healy (USA). The escort duties of each ship depended on the science that was being
collected. During seismic operations Healy was lead and during hydrographic ops Louis
S St Laurent was lead. This was done to utilize the best tools of each ship. The
bathymetry collected on this program will augment and refine the historical information
to establish and support Canada’s UNCLOS submission. The Canadian Hydrographic
Service team consisted of Jon Biggar, Jim Weedon and Marcus Beach (Central and
Arctic Region). Dave Street (Newfoundland Region) was the CHS representative
onboard the USCGC Healy. As in the past two single beam sounding techniques were
employed: conventional ship configuration and helicopter spot soundings. The ship
navigated along predetermined transects and the helicopter was deployed to collect spot
sounding data between the survey lines. The ship logged over 10,070 line kilometers
(Figure1) and the helicopter collected 61 spot soundings (Figure 2). In addition a 3.5
KHZ Knudsen sounder was deployed in open water when the seismic gear was not
configured for navigating in ice. The USCGC Healy joined the program on August 10th
and departed September 4th, during which time additional hydrographic data was
collected including deep water multibeam and 3.5 kHz single beam by USCGC Healy. In
addition to our regular responsibility CHS deployed Expendable Conductivity,
Temperature and Density Probes (XCTD) / Expendable Bathythermograph probes (XBT)
daily and monitored the continuous underway sampling of near-surface seawater as part
of the study of the oceanography of the Beaufort Gyre and Canada Basin.
The success of this year’s program can be contributed to the dedication and hard work of
the captains and crew of the CCGS Louis S St Laurent and the USCGC Healy and the all
the support staff.
70
Figure 3-40
– Work area, the red line
indicates single beam sounding line
coverage
Sounding Methods
Two single beam sounding methods were employed to collect data on the Louis S St
Laurent: conventional ship sounding and helicopter spot sounding. (Figure 4) The
helicopter, a Messerschmitt MBB BO105, was used to maximize the area covered and to
collect data inaccessible to the ship because of ice conditions.
71
Figure 3-41. Knudsen 320B/R Plus sounder and
PC interface was located in the Oceanographic
lab on the 300 level. The sounder is a dual
frequency configuration with the high frequency
set to 12 kHz and low frequency reserved for a
3.5 kHz transducer which is not installed.
The ship collected depths using the Knudsen 320B/R Plus sounder attached to a 12 kHz
transducer. The system used Chirp pulse generation technology. The system was operated
remotely using Knudsen Echo Control Client and Echo Control Server software via a
network connection in the aft seismic lab. When sounding with an icebreaker, bottom
detection was lost due to interference from ice/ship’s bubbler system and sea state.
(Figure 3) The echo sounder preformed well with the exception of logging extra files.
Normally the keb and kea format files are logged and when sgy format files were added
to the logging sequence the Knudsen files became corrupt, computer crashes and poor
performance were experienced. Knudsen Echo Control Client v1.47 and Echo Control
Server v1.74 software were used for acquisition and PostSurvey v2.24 software was used
for viewing during post processing of the data. The 3.5 kHz Knudsen was deployed
during open water opportunities. The system was is use for 4 days and preformed well.
72
12 kHz transducer
location
Figure 3-42. 12 kHz transducer acoustic window in hull.
Figure 3-43. transducer below landing on deck
Similar to previous years the Knudsen sounder and computer interface on the ship would
periodically lock up and require a system reboot.
The spot sounding procedure was performed in open water. The open water
technique was achieved by Helicopter with
73
slinging the transducer below the helicopter and placing into the water while in a hover.
Two models of Knudsen echo sounders using a fixed frequency of 12 kHz were used,
320A and 320M. The Knudsen 320M was prone to HF radio transmissions and simply
required a ground wire to the aircraft frame to rectify the problem.
Figure 3-44. Helicopter spot soundings (yellow dots) collected during program.
74
Figure 3-45. Spot
sounding in open
water, showing 12
kHz transducer slung
below helicopter
The sounders were set to a fixed
velocity of 1500 m/sec and then
corrected to an averaged true
velocity derived from the sound
velocity casts. In the open water,
marks were placed on the tether to
which the pilot would submerge
the transducer and this number was
applied as a draft value to the
sounding. The whole process under
ideal conditions was expected to
take 2 to 4 minutes per location.
The ice condition in most cases
was lighter than previous years.
The data was logged to a laptop
and post processed in Excel. The
helicopter logged 11.5 hours of
flight time to collect 61 spot
75
soundings. This season weather hampered the operations and only four days of the
scheduled 12 days spot sounding was achieved. The remaining part of the cruise was
further south or in United States waters where spot soundings were not required.
Figure 3-46. Knudsen sounder and laptop
A small chain was added to the sling below the transducer and grounded to the aircraft
frame/hook This elimated most of the static electrical charge that the aircraft built up
during flight. A break away electrical connection to the transducer point was also
incorporated for emergency use. The laptop was not connected to helicopter power but
ran on its internal batteries to elimate any problems with static electicity.
Figure 3-47. As recommended from
previous year a permanent GPS antenna
mount was attached on the dash of the
B105
76
Figure 3-48.
3.5 KHz transducer mounted to
seismic air gun sled (left) and
Knudsen Chirp 3260 sounder (right).
Figure 3-49.
Typical echo traces
(Echo Control
window) when
travelling in heavy
ice conditions
77
Positioning Methods
Figure 3-50. MSat coverage map for CDGPS corrections
The positioning systems used for both methods of data collection were the NovAtel
Propak V3 GPS receivers with L2 antennas. Differential corrections were received from
the nation-wide CDGPS service by means of MSAT satellite communications. The
correction data is based on algorithms developed by Natural Resources Canada (NRCan)
and real-time positioning data from Canadian reference stations. The estimated
positional accuracy was less than 2.0 metres in static mode. Differential corrections were
received for most of the voyage. The estimated positional accuracy without corrections
was less than 5.0 metres. All equipment performed well overall.
78
NovAtel GPS receiver located on bridge and antenna on monkey’s island above
ship’s bridge.
Figure 3-51. NovAtel DL V3 GPS receiver in the equipment rack located on the bridge of the ship.
Positions were fed directly to seismic lab for distribution to various computers/navigation programs.
79
Figure 3-52. NovAtel software interface used to configure and monitor NovAtel GPS receiver
Figure 3-53. HyPack logging software
80
Data Collection
For navigation and planning, HyPack v7.0 (single beam survey module) was used to
monitor and collect the survey data. Sound velocity and temperature were acquired using
an Applied Microsystems SV Plus v2. With the ship stopped, the sensor was deployed
from the ship’s starboard A-frame. Measurement accuracies from the manufacturer
specifications are sound velocity: 0.05m/s with 0.03 m/s precision; temperature: 0.005ºC,
pressure: 0.01% full scale (approx 0.5m). Three profiles casts were taken with maximum
depth of 3850m. (Figure 5) Additional profiles were obtained and compared to with
XCTDs and XBTs.
Figure 3-54. Science winch with SV Plus v2 (sound velocity meter) depth range 5000 metres (SVP)
mounted.
81
Figure 3-55. The data were downloaded from SV Plus v2 using Smartalk v2.27 software.
Figure 3-56. The setup used for downloading XCTD/XBT using the MK21 USB DAQ – Surface ship.
Bathythermograph Data Acquisition system and LM-3A Hand-Held Launcher (Lockheed Martin Sippican)
82
Figure 3-57. Locations of Sound Velocity casts in survey area.
83
0
SVP/Expendables 2010 - LSSL
jd222_1 XCTD
jd233 SVP(2010)
500
jd239 SVP(2010)
jd254 SVP(2010)
1000
Depth in Metres
1500
2000
2500
3000
3500
4000
1430
1440
1450
1460
1470
1480
1490
1500
1510
1520
Speed of Sound m/sec
Figure 3-58. Figure 5 - SVP / XCTD graph/profiles
84
Processing Methods
CARIS (Computer Assisted Resource Information System) GIS v4.4 was used for
managing, compiling, and visualization of the results of the processed bathymetric data.
CARIS HIPS/SIPS v7.0 (Hydrographic Information Processing System/Sonar
Information Processing System) was used for survey data processing of positions and
depths.
Figure 3-59. NRCan Seismic lab onboard CCGS LSSL showing Navigation (collection) Knudsen sounder
control and processing station
The processing steps consisted of: file conversion from HyPack to the HIPS/SIPS format,
navigation editor to clean/edit ‘vessel’ position, single beam editor to clean/edit depth
information and line processing which merges final position and depth files while
applying tide reductions and sound velocity corrections. The ship’s gyro information was
logged and applied to the data to correct for GPS/transducer offsets. The ship’s draft was
verified weekly and confirmed by deploying small launch to read the draft marks.
85
Science
Physical Oceanographic Program for DFO -IOS (Institute of Ocean Sciences)
CHS monitored the continuous underway sampling of near-surface seawater temperature,
salinity and phytoplankton (fluorescence), and dissolved gases. The ship’s seawater loop
system draws seawater from below the ship’s hull at approximately 9m, to the main lab
(“aft lab”). This system allows measurements to be made of the sea surface water without
having to stop the ship for sampling. Physical seawater samples were taken at frequent
regular intervals above 75N.
Expendable Deployments
XCTD (eXpendable Conductivity – Temperature – Depth) and XBT (eXpendable
Bathythermograph probes) probes were launched by a hand launcher LM-3A from
the stern of the ship to measure the physical seawater properties to depths of 460 m to
1870 m (depending on the unit). The data is communicated back to a digital data
converter (MK-21 USB DAQ) and a computer onboard the ship by a fine wire which
breaks when the probe reaches its maximum designed depth. Profiles were collected at 47
stations along the ship’s track. (34 XCTD, 14 XBT, 3 deep-water SVP cast)
Recommendations and Conclusions
As stated in the previous years reports the ship should be outfitted with another 12 or 3
kHz transducer for redundancy. If for some reason the existing system fails there is no
alternate method for bathymetry collection in deep water. All hydrographic computers
were replaced this year and all functioned without problems. A racked mounted
uninterrupted power supply (UPS) was also installed. The SV Plus v2 (sound velocity
meter) was recalibrated but required software updates to function properly. All
equipment performed well with the exception of minor software and cabling problems.
Three CHS staff is sufficient for sounding operations onboard ship. The program
involved two icebreakers; the CCGS Louis S St Laurent (Canada) and USCGC Healy
(USA). The software should be upgraded to the newest version for the 12 kHz Knudsen
sounder, this might provide a more stable logging environment. This proved to be the
best arrangement with each ship dependent on one another for ice breaking capabilities
and the science collected. During seismic operations Healy was lead and during
hydrographic ops Louis S St Laurent was lead. This utilized the best tools of each ship.
Acknowledgements
CHS would like to thank the NRCan group for their help and support and the captains
and crew of CCGS Louis S. St-Laurent and USCGC Healy for their assistance carrying
out the UNCLOS objectives. A special thank you note to the CHS staff for their hard
work and dedication.
86
Table 3-11. Major Equipment and Software Programs
CCGS Louis S St Laurent
Knudsen 320B/R Plus sounder
12 kHz transducer
NovAtel DL V3 GPS receiver / NovAtel L Band antenna
1 Desk top and 2 rack mounted computers running Windows XP
SV Plus v2 (sound velocity meter) depth range 5000 metres (SVP)
NovAtel CDU v3.2.1.3
MK21 USB DAQ – Surface ship Bathythermograph Data Acquisition system and LM3A Hand-Held Launcher (Lockheed Martin Sippican)
XSV02 (Expendable Sound Velocity Probe)
XCTD -1-2 (Expendable Conductivity, Temperature and Density Probes)
XBT T-6 (Expendable Bathythermograph probes – 460 m)
CCG Helicopter 363 (B105)
Knudsen 320A sounder (variable frequency capacity)
Knudsen 320M sounder 12 kHz
12 kHz Knudsen transducer
NovAtel Propak V3-RT2 GPS receiver / NovAtel L Band antenna
GoBook XR-1 laptop / HyPack software / Knudsen software
Dell laptop M6400
Operating Software:
HyPack 7.0
CARIS 4.4A
Caris Hips/Sips 7.0
Smartalk v2.27 software
Knudsen Echo Control Client v1.77 and Echo Control Server v1.55 software
87
Table 3-12. Locations of XCTD (eXpendable Conductivity – Temperature – Depth) and XBT (eXpendable
Bathythermograph probes) and SVP (Sound Velocity Probe)
Description
Latitude (N)
SVP Deep water cast 73.69433343
SVP Deep water cast 76.60547432
SVP Deep water cast 81.78446433
XBT t-6 Cast
72.0.323221
XBT t-6 Cast
72.80393344
XBT t-6 Cast
73.48392518
XBT t-6 Cast
73.68737273
XBT t-6 Cast
73.08942998
XBT t-6 Cast
72.49452942
XBT t-6 Cast
71.86156149
XBT t-6 Cast
72.37567827
XBT t-6 Cast
73.21891421
XBT t-6 Cast
73.98265644
XBT t-6 Cast
74.75634477
XBT t-6 Cast
75.82747286
XBT t-6 Cast
76.3551426
XBT t-6 Cast
78.34531618
XCDT-1 Cast
76.52691438
XCDT-1 Cast
76.72770615
XCDT-1 Cast
76.78676639
XCDT-1 Cast
76.84922247
XCDT-1 Cast
76.14843125
XCDT-1 Cast
75.37207312
XCDT-1 Cast
75.28337329
XCDT-1 Cast
75.73620642
XCDT-1 Cast
76.16179506
XCDT-1 Cast
76.16401291
XCDT-1 Cast
76.2904055
XCDT-1 Cast
76.44220963
XCDT-1 Cast
76.58788134
XCDT-1 Cast
7.39086233
XCDT-1 Cast
78.19679833
XCDT-1 Cast
78.44767927
XCDT-1 Cast
78.85768809
XCDT-1 Cast
78.99502011
XCDT-1 Cast
79.72293589
XCDT-1 Cast
80.88969615
XCDT-1 Cast
81.07770128
XCDT-1 Cast
81.74850222
XCDT-1 Cast
82.44679823
XCDT-1 Cast
82.44698137
XCDT-1 Cast
81.78215612
Longitude (W)
142.47912
146.40394
128.30804
145.40831
145.37776
145.33000
146.06136
147.99633
149.84793
151.42195
151.51827
151.00479
150.52804
150.20655
156.29856
151.70138
151.01525
128.74297
132.28779
133.64919
135.62282
136.12457
136.41165
152.56114
155.00697
156.05901
156.02567
153.14582
149.78703
146.47227
149.94839
152.33674
150.12482
146.38206
145.09886
141.34475
137.82035
137.94987
138.55654
137.97025
137.96675
128.33771
Time (GMT)
20:51:46
17:04:17
17:05:45
15:12:41
0:58:09
15:15:10
2:40:04
15:16:07
2:59:47
14:54:30
2:52:32
15:06:42
2:49:48
14:59:32
19:51:46
19:52:18
19:42:15
01:26:50
14:52:02
19:34:14
2:54:25
14:48:59
02:35:49
03:04:11
14:50:27
03:03:35
03:10:21
14:53:37
02:49:55
14:44:44
02:54:24
15:04:47
02:52:10
14:45:05
18:36:06
02:54:46
17:50:14
19:33:47
01:38:56
14:53:21
14:57:42
16:10:41
Date
09/11/2010
08/21/2010
08/27/2010
08/13/2010
08/14/2010
08/14/2010
08/15/2010
08/15/2010
08/16/2010
08/16/2010
08/17/2010
08/17/2010
08/18/2010
08/18/2010
08/19/2010
08/20/2010
08/22/2010
09/03/2010
09/03/2010
09/03/2010
09/04/2010
09/04/2010
09/05/2010
08/19/2010
08/19/2010
08/20/2010
08/20/2010
08/20/2010
08/21/2010
08/21/2010
08/22/2010
08/22/2010
08/23/2010
08/23/2010
08/23/2010
08/24/2010
08/25/2010
08/25/2010
08/26/2010
08/26/2010
08/26/2010
08/27/2010
88
Description
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-1 Cast
XCDT-2 Cast
XCDT-2 Cast
XCDT-2 Cast
Latitude (N)
82.18497857
81.34126666
80.98233202
80.48954386
77.36920653
78.85999037
71.28860186
71.28307866
72.80959117
Longitude (W)
134.28919
122.46752
118.99645
123.68198
136.88243
135.57674
137.0799
137.09843
145.37811
Time (GMT)
00:22:24
14:42:07
23:43:07
16:57:27
23:29:50
14:49:56
17:50:05
18:10:08
01:03:48
Date
08/27/2010
08/28/2010
08/28/2010
08/29/2010
08/30/2010
08/30/2010
08/10/2010
08/10/2010
08/14/2010
89
Table 3-13. Ship Activity Log
Date
JD
Time (UTC)
4-Aug
216
1700
Board Ship
5-Aug
217
0000
Attended orientation
6-Aug
218
1720
Started travelling
8-Aug
220
9-Aug
221
10-Aug
222
1500
1615
1900
1925
2000
0500
0525
0826
1256
1800
1900
0000
0200
0215
0909
1107
1535
1702
1750
1810
1815
0000
0000
0051
0935
1320
1807
2230
0247
0411
xxxx
2142
2150
1330
1420
1507
2212
2309
2317
2355
Started Logging - HyPack, Sounder 12kHz
Started Logging - Sounder 3.5 kHz
Seismic guys testing/fixing gear
Test SVP - Still not right config file
Seismic gear up and running
12 kHz sounder crashed
3.5 kHz sounder windows error (4-5 runtime errors during night - restart)
start line segment 2 ( shallow water ~50-60m)
start line segment 3 (start shallow head north)
Heading down slope past a few pingos
Start Processing
Start Processing JD220 and part of JD221
Backed up RAW and KEB/A files to External drive for JD220, JD221
Commenced turn for line segment 4
Started line segment 5
Backed up RAW data ('c:\Preprocess') to sounding pc
End work on line 5 - breaking off to pull gear and heads towards Healy
3.5 kHz sounder shut down - pull gear out of water
XCTD-2 cast _1 71°17'19"N 137°04'48"W
XCTD-2 Cast _2 71°16'59"N 137°05'54"W
Seismic gear out of water - steaming to meet with Healy
meet Healy
Lost bottom due to ship maneuvers
Bottom found again - image poor
Losing bottom due to rapid changed in depth - increased range to 500m
Weak return due speed increase to 17kt (back tracking) Medavac to Tuk
bottom digitizing poor (16.5 knots)
Test New SVP instructions - appears to be working
Single Beam Edit process JD221, most JD 222
Reached medavac drop off point
Processing JD222, 223
Stop/Start logging for start of selected line #1
deploying gear
bits and pieces of ice starting
start of new line (7)
XBT Cast_1 72°19'10"N 145°24'30"W
Streamer dead
Small Gun in Water
Retrieve Gear
Gear Back In Water
11-Aug
223
12-Aug
224
13-Aug
225
Activity
SVP
1
2
1
90
3
14-Aug
15-Aug
16-Aug
226
227
228
17-Aug
229
18-Aug
230
19-Aug
20-Aug
21-Aug
231
232
233
0052
0058
0103
0105
1040
1445
1515
1545
0035
0041
0109
0240
0435
0440
1516
1848
2236
0259
0443
1330
1350
1454
1800
1838
2200
0252
1506
1900
0001
0014
0139
0225
0249
0250
1459
1506
1800
1813
1900
1919
2020
0207
0315
1450
1951
0303
0313
0320
0515
1453
1952
0045
0249
1444
1510
1600
1704
1800
Back ON Line
XBT Cast_2 72°48'14"N 145°22'40"W
XCTD-2 cast_3 72°48'35"N 145°22'41"W
passing through some ice flows
stopped in ice - still logging - maneuver out
resuming course
XBT Cast_3 73°29'02"N 145°19'48"W
Buoy in water
passing through ice / blanking sounder
Buoy in Water
HIPS 2010 backup to Sounder computer
XBT Cast_4 73°41'15"N 146°03'41"W
Lost bottom
found bottom
XBT Cast_5 73°05'22"N 147°59'47"W
around large ice flow
waves on beam - hard to pick up bottom
XBT Cast_6 72°29'40"N 149°50'53"W
lost bottom
heading off course
regain bottom
XBT Cast_7 71°51'42"N 151°25'19"W
Eel back in water
Start of line north
restart HyPack to sync time
XBT Cast_8 72°22'32"N 151°31'06"W
XBT Cast_9 73°13'08"N 151°00'17"W
entering moderate ice
Stopped logging GPS data - wrong receiver type to collect the data requested by Terese
lost bottom reading (air/ice under hull?)
regain bottom (right where we left it)
HIPS\UNCLOS2010 backup to External Drive
XBT Cast_10 73°58'58"N 150°31'41"W
Crossed to outer side of EEZ
XBT Cast_11 74°45'23"N 150°12'24"W
Stop/start Survey/ reload line
Lost bottom
Regained Bottom
lost bottom
regained bottom
start divert around ice flow - off line
Back on line after divert around ice
XCTD-1 Cast_1 75°17'00"N 152°33'40"W
XCTD-1 Cast_2 75°44'10"N 155°00'25"W
XBT Cast_12 75°49'38"N 156°17'55W
XCTD-1 Cast_3 76°09'42"N 156°03'32"W
XCTD-1 Cast_4 76°09'50"N 156°01'32"W
lost bottom
regain bottom
XCTD-1 Cast_5 76°17'25"N 153°08'45"W
XBT Cast_13 76°21'19"N 151°42'
Jon trial run in Helicopter w/ transducer
XCTD-1 Cast_6 76°26'32"N 149°47'13"W
XCTD-1 Cast_7 76°35'16"N 146°28'19"W
Shut down gear/guns/streamer
Start SVP cast to 3800m
SVP cast down to 3800m 76°36'20"N 146°24'14"W
Draft 8.75m & 8.65m keep 8.7m in file
91
2
3
3
4
5
6
7
8
9
10
11
1
2
12
3
4
5
13
6
7
1
22-Aug
234
23-Aug
235
1820
0254
1504
1942
0111
0252
1445
1830
24-Aug
25-Aug
26-Aug
236
237
238
1830
~2030
0254
0410
0440
0500
0750
0540
1600
1750
1933
2025
2240
0138
1127
1145
1453
1457
~1930
2222
2230
27-Aug
239
28-Aug
240
29-Aug
241
30-Aug
242
31-Aug
1-Sep
243
244
2-Sep
245
0022
0115
1410
1512
1600
1610
1705
1815
2145
0000
0230
1442
2343
2355
0157
1657
1754
0015
1449
2329
1200
0500
0845
0100
completed SVP cast
8
XCTD-1 Cast_8 77°23'27"N 149°56'54"W
9
XCTD-1 Cast_9 78°11'49"N 152°19'57"W
14
XBT Cast_14 78°20'43"N 151°01'
HIPS 2010 backup to External Drive
10
XCTD-1 Cast_10 78°26'52"N 150°07'24"W
11
XCTD-1 Cast_11 78°51'28"N 146°22'52"W (recording ended early ~200m due to ice
flow)
XCTD-1 Cast_12 78°59'42"N 145°05'56"W (recording ended early ~400m due to ice
12
flow)
pulled gear to transit north/ break for Healy
Jon out on heli run - sounder/transducer not working properly - came back
13
XCTD-1 Cast_13 79°43'23"N 141°20'41"W (recording ended early ~300m due to ice
flow)
ship engine/shaft problems - stopped
ship going again
ship engine/shaft problems - stopped again - long term - in 9/10 ice cover
stopped logging HyPack & Knudsen files due to engine repair ongoing
ship now moving again
change of course - head to point 28 (line 28-29)
14
XCTD-1 Cast_14 80°53'23"N 137°49'13"W (recording ended early ~200m due to ice
flow)
15
XCTD-1 Cast_15 81°04'40"N 137°57'00"W
Jon out on heli run
Jon back from heli run
16
XCTD-1 Cast_16 81°44'55"N 138°33'24"W
gear in water for line 28>29
started line 28
17
XCTD-1 Cast_17 82°26'48"N 137°58'13"W (recording ended early ~200m due to ice
flow)
XCTD-1 Cast_18 82°26'49"N 137°58'00"W (recording ended early ~400m due to ice
18
flow)
Jon Leave on Heli Run
Jon return from Heli Run
problems with water sampler in wet lab - hose got loose - water on floor (different one than last
time)
19
XCTD-1 Cast_19 82°11'06"N 134°17'21"W (recording ended early ~375m)
Backed up HIPS\UNCLOS2010 to external drive
Move to open water to retrieve gear
recover gear
SVP in water
20
XCTD-1 cast_20 81°46'56"N 128°20'16"W
2
SVP cast down to 3572.22m 81°47'04"N 128°18'29"W (3600 counter/ 3617 sounder)
SVP operations complete
Problems with gear - gear out/in twice
Shut down and Restart both Survey Computers
Gear out - change over to Breaking for Healy
21
XCTD-1 Cast_21 81°20'29"N 122°28'05"W
22
XCTD-1 Cast_22 80°58'56"N 118°59'56"W
Break off Line - Heading to Tuk
soundings difficult to get - see notes for times/depth recordings.
23
XCTD-1 Cast_23 80°29'22"N 123°40'56"W
soundings difficult to get - see notes for times/depth recordings.
soundings difficult to get - see notes for times/depth recordings.
24
XCTD-1 Cast_24 78°51'36"N 135°34'36"W
25
XCTD-1 Cast_25 77°22'09"N 136°52'57"W
Reloaded Survey to sync time
Stopped outside of Tuk - Heli Back from drop off
Turn Around to head north
Fire & Boat drill
92
3-Sep
246
4-Sep
247
5-Sep
248
6-Sep
7-Sep
249
250
8-Sep
251
9-Sep
252
10-Sep
253
11-Sep
254
12-Sep
255
13-Sep
14-Sep
256
257
0140
0200
0110
0126
1452
1628
1830
1934
2247
0106
0254
0415
1448
2135
2326
2330
2335
0220
0235
1405
1420
0126
1350
1530
1725
1825
1917
2000
2318
2319
2329
0012
2130
1510
1528
1723
1732
1952
1956
2005
0117
2354
1950
2051
2150
1812
2130
1724
1605
Fire & Boat Drill completed
Backed up HIPS\UNCLOS2010 to external drive
Gear going back in water
26
XCTD-1 Cast_26 76°31'37"N 128°44'35"W (recording ended early ~950m)
27
XCTD-1 Cast_27 76°43'40"N 132°17'16"W (recording ended early ~260m)
Jon Leave on Heli Run
Jon return from Heli Run
28
XCTD-1 Cast_28 76°47'12"N 133°38'57"W
Jon Leave on Heli Run
Jon return from Heli Run
29
XCTD-1 Cast_29 76°50'57"N 135°37'22"W
Made turn to the south
30
XCTD-1 Cast_30 76°08'54"N 136°07'28"W
Started Logging .SGY files on Knudsen 12kHz
Jon Leave on Heli Run
Jon return from Heli Run - problems
Jon Leave on Heli Run
Jon return from heli Run
31
XCTD-1 Cast_30 75°22'19"N 136°24'42"W
Echocontrol crash/ KEB, SGY files stopped recording - HyPack continued ok
Echocontrol back up
Reloaded Survey to sync time
lost bottom
restart Knudsen computer
restart Knudsen computer
restart Knudsen computer
restart Knudsen computer - stopped logging SGY during repeated starts and lost bottom
restart Knudsen computer
bottom return - changed course
restart Knudsen computer
restart Knudsen computer
logging SGY files again
Pump in science lab shut down - restart 2200 - system back up JD252 0500
DAS computer freeze while processing NAV in HIPS - data lost ~ 1 min
DAS computer freeze while processing NAV in HIPS - data lost ~ 1 min
Reboot Knudsen computer (main) and local
Start record KEB and SGY again
Restart Echocontrol client - seemed to run slow
SGY files slowing down KEB display recording
Stop recording SGY files due to slowing down recording of KEB file
Backed up HIPS Processed Data + UNCLOS2010 directory (processed data in main HIPS dir)
Reset DAS computer power (mistake)
SVP operation begin
3
SVP reach max depth 3607.58m 73°41'39.6"N 142°28'44.8"W
(3620 counter/3665 sounder- touched bottom)
SVP operations complete
DAS computer freeze while processing NAV in HIPS - data lost ~ 3 min
Merged and exported all lines to date (JD255_1200)
Restart Echocontrol client - error - reconnect - restart sounder computer in lab
At Kugluktuk - End Logging
93
Chapter 4: Seismic Source Calibration
David C. Mosher
Questionable results from 2009 calibration trials required another attempt to be made this
year. All possible factors are accounted including complete recalibration of
hydrophones, signal conditioning unit, digitial acquisition system and cabling. In
addition, water velocities were measured and, in the deep tow experiment, a depth sensor
was used on the hydrophone. Two separate trials were conducted; one for the shallow
tow configuration and one for the deep tow configuration. The full 1150 in3 array was
recorded as well as each gun individually and the 2x500 in3 guns together. Only data for
the full array have been analysed for this report.
Figure 4-60. Seismic gun array configuration for shallow tow. The 150 in3 gun is in the lead and the two
500's astern.
Source Signature Test: Shallow Tow Array Configuration
JD 222
Ship Position: 71.3058º -136.9920º
Equipment and configuration
Hydrophone: NRCan #22;
94
Calibration (June 11, 2010), -200.3 dB//V/uPa (low gain) on SCU #6
GSCDig #4 Channel 1
0.9794 = calibration factor of GSCDig 4 Ch 1 (June 11, 2010)
SCU-6 s/n 025
Realtime Systems LongShot firing system
SCU 6 settings
Input: Seistec J1
Output = input A
dc power
no gain (low) switch setting
Configuration
Hydrophone Cable out 300 ft (91.44 m), deployed from stern
Gun Array 33 m from stern
Gun array depth = 6 m
Trigger/Fire delays = 58 ms
Digitizer Settings
Sample Interval 50 s
Sample Frequency 20 kHz
Number Samples 9216
Record Length 460.8 ms
Test 1
filename: caltestlsl2010_2010_222_16_10_23.sgy
full array = 2x500 cu.in. G guns and 1x150 cu.in. G gun
Pressure = 1950 psi
31 shots
Test 2
filename: caltestlsl2010_2010_222_16_15_37.sgy
array= 1x 150 cu.in. g gun
pressure 1950 psi
14 shots
Test 3
filename: caltestlsl2010_2010_222_16_18_05.sgy
1x500 cu.in. G gun
pressure 1950 psi
10 shots
Test 4
filename: caltestlsl2010_2010_222_16_19_50.sgy
2x500 cu.in. G guns
pressure 1950 psi
95
18 shots
Test 5
filename: caltestlsl2010_2010_222_16_22_50.sgy
1x500 cu.in. G gun and 1x150 cu.in. G gun
pressure 1950 psi
14 shots
96
Source Signature Test: Deep Tow Array Configuration
JD 248
Equipment
Hydrophone: NRCan #22;
Calibration (June 11, 2010), -200.3
dB//V/uPa (low gain) on SCU #6
GSCDig #4
Channel 1 = Shot record; naming convention
= LSSL2010_Deep_towNRC-H022_"time
stamp".sgy; 0.9794 = calibration factor of
GSCDig 4 Ch 1 (June 11, 2010)
Channel 2 = Fire break Point, naming
convention LSSL2010_Deep_towRTS_AngFTB_"time
stamp".sgy
SCU-6 s/n 025
Realtime Systems LongShot firing system
SeaStar mini-CTD (attached to hydrophone to
provide depth for second set of filenames
provided below), Filename= 1S5274.DAT
Figure 4-61. Design and measurement parameters
of the Sercel G-gun array for CPMSRRS 2010
SCU 6 settings
Input: Seistec J1
Output = input A
dc power
no gain (low) switch setting
Configuration
Hydrophone Cable out 400 ft (121.92 m), deployed from stern
Gun Array 0 m from stern
Gun array depth = 12 m
Trigger/Fire delays = 56.7 ms (determined from GSCDig Chan 2 data
Digitizer Settings
Sample Interval 20 s
Sample Frequency 50 kHz
Number Samples 50000
Record Length 1000.33 ms
97
Test 1
filename: LSSL2010_Deep_towNRC-H022_2010_248_02_38_47.sgy
filename: LSSL2010_Deep_towNRC-H022_2010_248_02_55_42.sgy
full array = 2x500 cu.in. G guns and 1x150 cu.in. G gun
Pressure = 1950 psi
11 shots
Test 2
filename: LSSL2010_Deep_towNRC-H022_2010_248_02_47_14.sgy
filename: LSSL2010_Deep_towNRC-H022_2010_248_02_59_00.sgy
array= 1x 150 cu.in. g gun
pressure 1950 psi
10 shots
Test 3
filename: LSSL2010_Deep_towNRC-H022_2010_248_02_43_24.sgy
filename: LSSL2010_Deep_towNRC-H022_2010_248_03_00_40.sgy
2x500 cu.in. G gun
pressure 1950 psi
10 shots
Test 4
filename: LSSL2010_Deep_towNRC-H022_2010_248_02_46_06.sgy
filename: LSSL2010_Deep_towNRC-H022_2010_248_03_02_18.sgy
1x500 cu.in. G guns
pressure 1950 psi
10 shots
98
Results
For this report, only results
for the full array (1150 in3)
are presented. Other
configurations, such as
single gun and pairs of
guns are logged and
archived but not analysed.
Measured results are
compared with modeled
results from GUNDALF
version 6.1 software
(Oakwood Computing). For
each test, and XCTD
deployment was used to
determine sound velocity in
Figure 4-62. Fire point signal digitized from the LongShot fire unit.
the water column. Since
the experiment takes place
within the top 100 m water depth, the velocities over the interval from 0 to 100 m were
averaged. Time difference between the trigger point and the fire point was recorded on
the GSCDig from the analog output of the LongShot firing unit, showing a 56.8 ms delay
between the two.
Shallow Tow configuration
Measured
Table 4-14. Average amplitudes (0-peak and peak-peak) for calibration trials with the shallow tow
configuration.
Tra
ce
93
94
95
96
97
98
99
100
101
102
103
104
105
Distance
(m)
68.832
68.5368
68.61168
67.00896
67.464
67.7736
66.456
64.9728
63.97056
64.91376
64.944
64.512
64.512
Amplitude
(Bar)
0.084935
0.087244
0.086779
0.084346
0.083983
0.08419
0.088852
0.084495
0.086067
0.091033
0.082689
0.085073
0.083606
Amplitude
(Bar.m)
5.84626096
5.979452718
5.954036627
5.651919597
5.665832746
5.705837785
5.904752985
5.489904441
5.50575545
5.909316147
5.370159657
5.488251836
5.393566762
0-Peak Amp
(dB)
198.5817562
198.8147523
198.768269
198.5212619
198.4838333
198.5051773
198.9733507
198.536664
198.6967353
199.1840092
198.3489633
198.5958705
198.4447111
0-Peak Amp dB re 1
m
235.3375639
235.5332287
235.49623
235.0439195
235.065275
235.1263884
235.4240347
234.7912957
234.8163383
235.4307445
234.599744
234.7886806
234.6375212
99
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
64.35072
64.35072
64.11024
63.40752
64.152
64.19088
64.44
64.008
64.43136
64.008
64.89648
64.728
64.89936
66.56976
66.84336
67.16448
67.968
68.20992
0.077917
0.080162
0.083376
0.086845
0.077805
0.077697
0.084906
0.083475
0.083461
0.080466
0.076361
0.08182
0.080468
0.076727
0.080714
0.079537
0.076308
0.070959
5.014024291
5.158462706
5.345276318
5.506625525
4.991323516
4.987418295
5.471340031
5.34306721
5.377486505
5.150487233
4.955587835
5.296069787
5.222299999
5.107716482
5.395178828
5.342034021
5.186479873
4.840104135
197.8326605
198.0793377
198.4208552
198.7748955
197.8201104
197.8080493
198.5787635
198.4311276
198.4296406
198.1122812
197.6574807
198.2572302
198.1124281
197.6989958
198.1389514
198.0113399
197.6513641
197.0201433
AVERAGE
Tra
ce
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
Distance
(m)
68.832
68.5368
68.61168
67.00896
67.464
67.7736
66.456
64.9728
63.97056
64.91376
64.944
64.512
64.512
64.35072
64.35072
64.11024
63.40752
64.152
64.19088
64.44
64.008
64.43136
64.008
64.89648
64.728
Amplitude
(Bar)
0.126513
0.129758
0.128586
0.134015
0.134019
0.136586
0.134314
0.133559
0.138963
0.137394
0.135887
0.135832
0.127801
0.125348
0.127878
0.136501
0.129474
0.127924
0.124839
0.126005
0.126888
0.13089
0.127976
0.120305
0.128248
Amplitude
(Bar.m)
8.708153164
8.893194642
8.822517207
8.980222263
9.04146469
9.256921847
8.925998667
8.677724947
8.88956764
8.91878186
8.825039753
8.762824874
8.244698081
8.066219935
8.229063448
8.751090874
8.209652655
8.206605228
8.013542211
8.119753207
8.121822784
8.433404658
8.191465162
7.807358109
8.30125444
Peak-Peak
Amp (dB)
202.0427134
202.2626795
202.1838892
202.5430842
202.5433341
202.7081208
202.5624524
202.5134859
202.8580097
202.7593755
202.6635527
202.6600725
202.130685
201.962333
202.13594
202.7026958
202.2436803
202.1390668
201.927024
202.007746
202.068385
202.3381128
202.1425466
201.6056592
202.1610307
234.0037287
234.2504059
234.5594032
234.8177109
233.9643144
233.9575159
234.7618741
234.5558127
234.6115866
234.2369663
233.9019036
234.479074
234.3572363
234.1645357
234.6401169
234.554133
234.2974539
233.6970941
234.6419945
Peak-Peak Amp dB re
1m
238.7985212
238.981156
238.9118503
239.0657417
239.1247758
239.3293319
239.0131364
238.7681176
238.9776128
239.0061108
238.9143334
238.8528826
238.3234951
238.1334012
238.3070082
238.8412439
238.2864957
238.2832709
238.0764906
238.1908566
238.1930702
238.5200588
238.2672318
237.850082
238.3828745
100
118
119
120
121
122
123
64.89936
66.56976
66.84336
67.16448
67.968
68.20992
0.128229
0.119822
0.127718
0.131413
0.12285
0.116722
8.321979858
7.976500973
8.537129615
8.826256046
8.349876022
7.961617095
202.1597249
201.5707086
202.1250721
202.3727373
201.7875107
201.3430749
AVERAGE
238.4045332
238.0362485
238.6262375
238.9155304
238.4336005
238.0200257
238.5753331
101
Figure 4-63. Shallow tow configuration calibration test result, shot 107. Top is a time domain shot
signature showing a zero to peak amplitude of 5.16 bar-m or 234 dB re 1 Pa at 1 m. Bottom is the
frequency spectrum plot for this trace, showing significant power between 2 and 60 Hz with notching
occurring at 100 to 120 Hz, caused by the bubble pulse period.
102
Model
Figure 4-64. Comparison of the measured and modeled time-signature results. Note the 0-Peak amplitude of the
model suggests 6.42 Bar-m (236 dB re 1 mPa @ 1 m), while the measured result is 5.16 Bar-m (234 dB re 1 mPa @
1 m). This difference is consistent but unexplained. See Appendix C for modeling results details.
Peak to peak in bar-m.
Zero to peak in bar-m.
RMS pressure in bar-m.
Model/Measure
Bar-m
12.9 / 8.50
6.33 / 5.40
4.48 / 2.375
Model/Measure
MPa
1.29 / 0.850
0.633 / 0.540
0.448 / 0.237
Model/Measure
db re 1 [email protected]
242 / 238.6
236 / 234.6
233 / 227
Table 4-15. Table of amplitude values reported from the model compared with the field measurement
(RMS was calculated for the initial positive and negative peaks of the signatures - a duration of 20 ms).
103
Deep Tow Configuration
Hydrophone
Depth
(m)
107
104.2
101.85
98.86
96.3
94.2
92
90.2
88.08
86.4
84.9
Hydrophone
Depth
(m)
107
104.2
101.85
98.86
96.3
94.2
92
90.2
88.08
86.4
84.9
Trace
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
Distance
(m)
106.44
107.60
108.11
108.58
109.18
109.44
109.65
110.49
110.72
111.44
111.79
Trace
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
Distance
(m)
106.44
107.60
108.11
108.58
109.18
109.44
109.65
110.49
110.72
111.44
111.79
Amp (Bar)
0.049692425
0.04803056
0.04695705
0.047067735
0.047847748
0.046665367
0.046593013
0.047146439
0.045459398
0.045696872
0.045353476
Average
Amp
(Bar.m)
5.289
5.168
5.076
5.111
5.224
5.107
5.109
5.209
5.033
5.092
5.070
5.135
0-Peak Amp
(dB)
193.93
193.63
193.43
193.45
193.60
193.38
193.37
193.47
193.15
193.20
193.13
0-Peak Amp
dB re 1
[email protected]
234.5
234.3
234.1
234.2
234.4
234.2
234.2
234.3
234.0
234.1
234.1
234.2
Amplitude (Bar)
0.090562924
0.094785972
0.092606064
0.093101652
0.095314902
0.090167815
0.093468864
0.09026285
0.086167498
0.090268747
0.088463308
Average
Amplitude
(Bar.m)
9.640
10.199
10.011
10.109
10.406
9.868
10.249
9.973
9.541
10.059
9.890
9.995
Peak-Peak
Amp (dB)
199.14
199.53
199.33
199.38
199.58
199.10
199.41
199.11
198.71
199.11
198.94
Peak-Peak
Amp dB re 1
m
239.7
240.2
240.0
240.1
240.3
239.9
240.2
240.0
239.6
240.1
239.9
240.0
Table 4-16. Average amplitudes (0-peak and peak-peak) for calibration trials with the deep tow
configuration.
104
Figure 4-65. Deep tow configuration calibration test result, shot 5307. Top is a time domain shot signature
showing a zero to peak amplitude of 5.135 bar-m or 234 dB re 1 Pa at 1 m. Bottom is the frequency
spectrum plot for this trace, showing prominent power between 2 and 60 Hz with notching occurring at 65
Hz, caused by the bubble pulse period.
105
Model
Figure4- 66. Comparison of the measured and modeled time-signature results. Note the 0-Peak
amplitude of the model suggests 6.33 Bar-m (236 dB re 1 mPa @ 1 m), while the measured result is
5.29 Bar-m (234.5 dB re 1 mPa @ 1 m). This difference is consistent but unexplained. See Appendix C
for modeling results details.
Peak to peak in bar-m.
Zero to peak in bar-m.
RMS pressure in bar-m.
Model/Measure
Bar-m
12.9 / 10.0
6.33 / 5.29
4.48 / 2.49
Model/Measure
MPa
1.29 / 1.00
0.633 / 0.529
0.448 / 0.249
Model/Measure
db re 1 [email protected]
242 / 240.0
236 / 234.5
233 / 228
Table 4-17. amplitude values reported from the model compared with the field measurement
(RMS was calculated for the initial positive and negative peaks of the signatures - a duration of 20 ms).
106
2009 Result
Figure 4-67. A comparison of measurements made in 2009 with those of 2010.
Discussion
Results of the 2010 calibration experiments are considered quality results. All known
variables are accounted for, including complete calibration of the hydrophone and
digitizing systems. The shape of the impulsive pressure response of the pneumatic array
is consistent from shot to shot and agrees well with the shape of predicted results from
the Gundalf 6.1 model, including pulse width and bubble oscillation period. Absolute
peak values however, are less, by 2 dB on average. This discrepancy cannot be readily
explained, but results are consistent amongst all shots and for the two separate
experiments. Given these measured results, assuming a 20LogR loss in the water column,
a zero-to-peak source level of 180 dB is reached at 500 m. This radius agrees with
attenuation results made in 2009 (see Mosher et al., 2009). In 2009 measurements,
however, the shape of the impulsive response was particularly unusual and could not be
explained. A fault in the calibrated hydrophone was found and clearly this had an
impact, if not on the amplitude level, then at least on the shape of the pulse recorded. As
a result, 2009 results are considered invalid and for all further analytical and processing
endeavours, the 2010 results should be employed.
Application of a mini-CTD on the hydrophone allowed the depth of the hydrophone
during the course of the experiment to be recorded. The depth clearly varied significantly
(see Table 2), but source levels are consistent. This result indicates the source is omnidirectional over the range of measurements made.
107
Chapter 5: Ice and Weather Observations
Bruno Barrette
108
Introduction
I joined the CCGS Louis S. St-Laurent with the crew change, in Kugluktuk, Nunavut, on August
4th , 2010 at 2100Z. I replaced ISS Erin Clark that had been with the ship from St John’s to
Kugluktuk. Erin would stay on board until August 10th, date at which she transferred to the
USCGC Healy to perform ISS duties on the American Ship
I completed my assignment on the CGBN on September 15th , date of the crew change. ISS
Erick Thibault will be replacing me.
Daily Log: Beaufort Sea Unclos Operations 2010
BREAK-DOWN OF LOUIS S. ST-LAURENT UNCLOS OPERATIONS (including ice
conditions along the way)
This part of the report summarizes, in chronological order, ship operations from August
4th to September 15th
2010. It also describes the ice conditions encountered along our way
August 4th :
ISS Bruno Barrette arrives on board at 14h00 PDT. In the evening, Erin Clark (ISS being
relieved) briefs me on the ISS duties and operational particularities of the work on CGBN
(familiarization).
It is to be noted that, during the whole UNCLOS survey mission, the USCGC Healy was
taking the CGBN under ice escort for the greatest portion of the voyage with the
exceptions of transit legs from one to another waypoint (science gear not deployed).
During those transits, the CGBN was the leading ship.
August 5th :
The ship remains in Kugluktuk. During that time, the new crew members are given the
usual shipboard security briefings (ship and helicopter). I also verify all ISS equipment in
preparation for ice operations. Most of the time is spent with Erin training on the IceNav
system. Operation on this system was entirely new to me. I received a one-day course, in
Montreal, two years ago and I had read the user’s manual prior to boarding. Erin did a
great training job.
August 6th:
Departure around noon. We were in Dolphin Union Strait at 17h30 PDT. Ice free waters.
August 7th:
Transit through Amundsen Gulf. Ice free waters.
August 8th:
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We arrive at the first deployment station. The routing of the test run had been chosen in
mostly open water so that the seismic gear can be verified and calibrated. The testing
took place overnight. Refer to the image on the next page for details of the route taken.
Take note that a diagram of the entire UNCLOS Mission Tracks has been inserted at the
end of the present document
August 9th:
Testing and verification of seismic equipment is well under way. The whole leg took
place in open water (see picture on the next page) since the ice edge had been drifting
with winds north of our travel line.
Erin and I discuss the routine that we will use to ensure good communication while she is
on the Healy.
That is:
(1)
Set times for daily weather and ice briefing preparations to ensure consistency and
accuracy,
(2)
Determination of which ice chart will be sent to CIS Ottawa daily
(3)
Identify the means that will be used to transfer data (imagery and ice information)
between the two ships.
It is to be noted that our routine worked very efficiently and that the line of
communication was excellent between the two of us. Also note that the ice charts
produced on CGBN, most of the time, were sent to Ottawa rather than the one produced
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on the NEPP. When airborne reccos were performed, the CGBN chart was always the
one sent out.
August 10th:
The science gear is brought back on board. We begin the transit to 141W, point where we
will rendez-vous with the USCGC Healy. The two ships meet, in open water, at 17H30
PDT (see image on the next page). Erin Clark transfers on the Healy and Caryn Panowicz
(Ice analyst with the NIC, in Washington) boards the CGBN at 18h30 PDT. I meet her on
the flight deck and, later on that night, give her a tour of the vessel. Comments on her
work on our ship appear further in this report.
August 11th:
The course set to reach the first leg of the UNCLOS program track lines must be altered.
A medevac trip was to be done to Tuktoyaktuk to ensure the safe return to land of one of
our crew members. The medevac course took us through open waters to within helicopter
range of Tuktuyaktuk.. The transfer was made late in the evening. The transit back to the
base leg of UNCLOS started overnight. The image on the next page shows the transit
route to the base of the first leg of science work. It shows the entire first line of seismic
surveying. The southern portion of Leg 01 was near the ice edge of sparsely distributed
TFY decayed ice that exceptionally lingered near 147W.
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August 12th:
We arrive at the base leg 01 at 15h00 PDT. The science seismic gear is deployed right
away. Science surveying work begins along a route to the NNE in direction of the main
ice edge. We attain the edge at about 1 AM on the 13th.
August 13th:
The first technical problems arise with the scientific equipment. Tests are done in open
water and we are back on course at 16h00 PDT. Ice conditions: Very low concentrations
of old ice in small floes (1 to 2/10) except at 7210N 14530W where a two nautical miles
wide band of ice shows 9/10 old ice.
August 14th:
The second portion of Leg 01 is completed by 15h00 PDT. The first part of Leg 02 in a
SW direction is undertaken. See the depiction of Leg 02 on the next page. Ice conditions:
the entire leg took place in generally easy to moderate ice conditions with 6 to 7/10 total
concentration with 4 to 5/10 of multi year ice (MYI) and 2 to 3/10 of decayed TFY.
August 15th:
The Leg 02, started yesterday, brings us back out to the ice edge at around 13h00 PDT
(7250N). Before reaching the edge, the ship was in light ice conditions showing 4/10 total
concentration with 3/10 old ice and 1/10 TFY. Past the edge we were in open water to the
end of the leg.
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We had to navigate through strong easterly winds blowing at a sustained 30K. The winds
continued overnight.
August16th:
Leg 02 was completed by mid-afternoon and we were on our way on Leg 03. We started
in open water. At the end of Leg 02, we encountered very light decaying old and TFY ice
(2/10 or less). We see an illustration showing legs 01, 02 and 03 on next page. Leg 03 is
the latter portion of the segments.
The picture below shows Leg 01, 02, and 03
The picture below shows waypoints of the fourth surveying leg (WP16 to 20). On the
next page, we see the diagram used by the science team.
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August 17th:
We are progressing along Leg 03. We rendez-vous with the USCGC Healy returning
from Barrow AK. The American ship picked up the replacement of the person evacuated
on medevac and equipment parts. A first helicopter recco was performed to the end of leg
03 . Ice conditions: southern portion to 74N: 3 to 4/10 ice with 90% old ice and 10%
decayed TFY – northern portion: 6/10 total concentration with 5/10 MYI (few thaw
holes) and 1/10 TFY. The picture below illustrates the ice conditions encountered
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August 18th:
The ship starts to make its way along Leg 04. A helicopter recco is done along the track
(to approx 100 NM ahead). A giant floe blocks our way at 75N 152W. It forces a
diversion of the course around 15H00 PDT (see image below). The science team is upset
to get off track. It seems that their data is greatly affected when the ship moves off track.
Notwithstanding, the easiest line of progression comes first. The floe was more than 10
NM across of solid MYI. The rest of the track presented 7/10 total concentration made of
5/10 MYI and 2/10 TFY with few ridges and thaw holes.
pro
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August 19th:
The first portion of the 4th leg is completed. Maintenance has to be done on the seismic
equipment. To put it back in the water, we need to travel to open water. It is decided that
a transit without measurements would be done to WP 18 (NW corner on the picture
above). The latter portion of leg 04 (142NM) is to the east (see track picture of preceding
page.). At the beginning of Leg 04, we found total concentrations between 6 and 9/10 of
ice with 85% old ice and 15% decayed TFY.
August 20th:
We continue our route to the last WP on route 04. A helicopter recco is done along our
track at very low altitude and foggy conditions.. Erin and Josh (US Ice Specialist)
accompany us. See recco results below. Note that the chart is NOT set North up.
August 21st
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Leg 05 is started (see picture next page). Seismic equipment continues to work without
problems. Pictures of ice conditions are sent to the Canadian Ice Service in Ottawa to
confirm the predominance of thick first year ice on our track. This information was used
to adjust the daily ice analysis chart (justifying photo next page). Reported ice conditions
were: 8 to 9/10 total concentration with 2 to 4/10 of MYI and 5 to 6/10 of decayed TFY.
With the cold temperatures, 1/10 of newly formed nilas was also reported (air temp was 3C and water temp -0.4C). Very few large floes of MYI were encountered.
August 21st - Leg 05:
August 21st: Predominance of thick first year on first portion of leg 05:
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August 22nd:
We continue our way on the second portion of Leg 05. A helicopter recco was done to the
end of the leg. Many pictures were taken. They were sent to CIS Ottawa and Sarnia Ice
Office. They depicted the predominance of TFY ice (or second year ice) in its late
melting stage and decayed old ice floes (proportion 6/10 TFY-SYI and 4/10 MYI). The
northeast portion of the leg (north of 79N) had a predominance of old ice. The picture
below is representative of these conditions.
August 23rd:
The planned tracks into the northern portion of the UNCLOS program (north of 80N) are
been mapped out. We start on the first portion today. To WP 23 (see chart on next page).
A helicopter recco is done ahead of ship. Ice conditions become clearly with a
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predominance of MYI and the floe sizes increase very significantly. However, ice is not
under pressure due to the absence wind. (see the picture below depicting ice conditions).
August 24th:
Last night, a serious mechanical problem arose with a shaft. It brought the ship to a halt
so the repairs could be done. The day was spent at 7950N 141W. Repairs were finished
late in the evening and the ship was on its way. The planned northern leg was modified to
include a dogleg of surveying over a newly discovered seamount (shown by WP23, 24
and 25). Waypoints 26 and 27 were established well to the north (up to 85N). See the
Canada Basin ice chart below showing the original planned track (WP23 to 29) along
with ice information.
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August 25th:
In light of the accumulated delays since the beginning of the mission, the members of the
science team decide to eliminate the northern legs of the originally planned track lines
(see above WP23 to WP28). The track was modified to become a direct survey line from
WP23 to WP 28. From there, the segment between WP28 and WP29 will be sounded. A
helicopter recco was done along the track between WP23 and WP28. As this point, there
was definite predominance of thick MYI. Conditions are now: 9/10 total concentration
with 8/10 MYI and 1/10 TFY. Many floes 2 to 5 NM across were seen. Progression of
our ships becomes more challenging.
August 26th:
Early in the morning, we are well on our way to WP29 (NW to SE portion of the track,
see illustration on the preceding page). A heli recco is done and shows the observe the
roughest ice conditions encountered so far on our trip (see pictures below). We observe
mostly thick MYI with many thaw holes. We found numerous vast and giant floes on our
track. All were reported on the chart. Significant ridge lines up to 15 feet in height barred
the track.
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August 27th:
Little progress was made today. Multiple adjustments needed to be made to the seismic
equipment. It was taken out and back into the water a few times. It was decided that the
back-up gear needed to be put in place. A CTD (Conductivity, Temperature, and Density)
was done along with expendable CTD’s. At 20h00 PDT, the seismic equipment is pulled
out for good, the CGBN then commence leading icebreaking duty taking along with the
USCGC Healy surveying on Multibeam. We are in direction WP29. Ice conditions: 8 to
9/10 mostly old ice (1/10 TFY) in large and very large floes.
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August 28th:
The ship almost reached WP29 when a medevac was declared. The evacuation would
take place in Tuktoyaktuk. The shortest ice route to the ice edge was chosen and the ship
redirected. The illustration below shows ice conditions along the medevac transit
(illustration is NOT north up). Ice conditions remain as yesterday, mostly MYI.
August 29th:
Pursuing on the medevac route, NEPP is the leading ship through ice. Conditions remain
in very closed pack of MYI with 1 to 2/10 TFY. There is presence of vast floes (2 to 10K
across).
August 30th:
Continuing our way south, we are out of the main MYI ice pack in the morning at 78N.
Concentrations diminish to 6 to 8/10 with predominance of MYI.
August 31st:
We attained the southern portion of the medevac route in late afternoon. The helicopter is
dispatched to Tuktoyaktuk at 18h30 PDT. The routing to reach the next science leg is
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established. The route was chosen as the longest possible distance in open water to reach
the ice pack NW of Banks Island (see picture below)..
September 1st:
Enroute in direction of the next science survey leg. Mostly in open water.
September 2nd:
A heli recco is done up to the starting WP (7630N) of the next science leg. Unfortunately,
the latter portion of it was performed with very limited visibility. Ice conditions were
difficult with 9/10 total concentration made of mostly MYI in mostly large or very large
floes. There was presence of ridging. WP 7630N is reached at 18h30 PDT. The seismic
surveying equipment is submerged and work is started. NEPP is leading for icebreaking.
September 3rd:
Surveying is continued in direction of the western end of the track. The illustration on the
next page shows the ship’s position at 17h30 PDT. Separation with the USCGC Healy
takes place at that time. Erin Clark returns on board and Caryn Panowicz returns to her
ship. Conditions on this leg change to an equal distribution between old and TFY ice.
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September 4th:
The ship is now on the southern portion of the leg. Ice conditions improve at 76N (lower
concentrations – 6 to 8/10). It is to be noted that significant concentrations (3 to 4/10) of
decayed second year ice were reported from 77N and south.
September 5th:
Continuation of the southern leg. Ice conditions: 8 to 9/10 total concentration with 4 to
5/10 MYI, 3 to 4/10 SYI and 1/10 TFY.
September 6th:
Open water is reached at approximately 72N. Continuation of the southern portion of the
leg.
September 7th:
The southernmost point of this leg is attained. The ship will now transit in open water to
the SE base of the last UNCLOS science leg to be done on this trip.
September 8th:
We transit to the beginning point of last science leg. The figure on the next page indicates
the ship’s position in the afternoon.
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to
September 9th:
The day is spent in open water in a NW direction to the end point of the last seismic
survey line.
September 10th:
The ship is close to completion of the survey line. An additional short portion of leg is
added to the original plan. The image on the next page shows the new planned route. The
ship reentered ice at 72N. Ice conditions to the end of the line were generally 3 to 6/10
total concentration with 85% old ice (MYI and second year) and 15% decayed TFY. A
section around 73N had higher concentrations closer to 9 to 9+/10.
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September 11th:
The very last portion of survey line for the 2010 UNCLOS project is completed at noon
time. The science gear is taken out of the water. An ice route is established to take the
path of least resistance out of the ice pack. The exit travel route begins at 14h00 PDT.
The picture on the next page shows the route chosen. The ice concentrations were never
more than 70% ice cover (25% of the time) and much lower around 3 to 5/10 (75% of the
time) mostly decayed MYI and SYI.
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finsi
September 12th:
The ship comes out at the ice edge at approximately 5h30 PDT. We take the open water
route in direction of Paulatuk where we will drop off our three marine mammal
observers.
September 13th:
We arrive in Darnley Bay (Paulatuk) early in the morning. The marine mammal
observers are airlifted back home. The ship is on its way for our crew change destination,
Kugluktuk, at 10h00 PDT. Open and ice free water from then on.
September 14th:
We arrive at destination, Kugluktuk, at in the morning. Crew change preparations are
undertaken.
September 15th:
Last day on board. Crew change operations are started at XXHXX PDT. It is the
conclusion of my ISS duties.
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Forty-one (41) daily ice observation charts (charts #12 to #52) were produced during this
trip. They were all, without exception, sent to the Canadian Ice Service in Ottawa.
Among these charts, eight (8) had, embedded in them, ice conditions determined by
helicopter reconnaissance flights. Flights were generally done ahead of the ship to a
distance of approximately 100 NM unless weather conditions warranted an early return.
Whenever required, draft charts were sent before at 1745Z daily, ahead of the final
version. This procedure ensures that the ice forecaster in CIS has preliminary ice
information to use in the production of the CIS daily ice charts.
Weather Conditions
Unsurprisingly, weather conditions during our entire Arctic trip were typical of the
Beaufort Sea summer season. I had heard of it, now I have seen it!!
For a month and a half (!), Beaufort Sea was under the influence of a stationary high
pressure system. From the day of our arrival in the region on August 9th to the day of
departure, September 12th, the Beaufort Sea was, for 34 days, in the anticyclonic flow.
Only two exceptions to that rule: on August 30th and on September 9th, where a trough
line of low pressure brushed the SW portion of Beaufort Sea which brought decks of
clouds at higher altitudes.
This anticyclone drifted with upper levels circulation from west to east and back
regularly but never by more than a few hundred NM. Being in the anticyclone signifies
that the colder air (cooled by the presence of the ice pack) is trapped under an ever lasting
inversion. When moisture from the surrounding open water is added to the mix along
with generally light winds (or even absence of circulation); you have the perfect recipe
for ever lasting FOG! It was a shallow layer of fog (extending from surface to a few
hundred feet upward) but fog nevertheless.
Indeed, we had, count them, twenty-five days with fog, reducing visibility between less
than one-half nautical mile and 6 nautical miles. Intermittently, when conditions were
favorable, the fog dissipated somewhat from mid-afternoon to early evening. That was
when there was enough warming in the lower levels to “burn” the fog from the top down
or when the wind was strong enough to lift the foggy layer up a few hundred feet into a
stratus layer.
Consequently, we were did not see sunshine for the longest time. The sun truly shined on
only six (count them!) days during our whole trip on the 17th and 18th of August, on the
22nd and 23rd of August and on the 8th and 9th of September. We saw the sun peak
through the fog on five other days (August 15, 24, 26 and September 3 and 4), that is
when the fog dissipated enough late in the day.
As for the wind patterns, we will easily understand that the circulation was invariably
characterized by light winds (15K or less). A few exceptions to the rule: on our transit to
Beaufort Sea, winds blew first from the SE at 20K on August 6th and then from the NE at
20-25K with gusts up to 35K on August 7th and 8th. The wind was attained gale force on
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the 8th generating significant waves and swell (up to 4.5 meters). We had a windy day on
August 15th, with easterlies at 25KG30K due to a trof line, on the Alaskan North Slope
shoreline, pushing and tightening the western high pressuregradient. The same
phenomenon repeated itself on the 7thand 8th of September when winds blew from the
SE at 25K with gusts up to 35K.
As for air temperature, if we make exception of the periods when we approached the
coastline, temperatures were absolutely stable, as expected in a anticyclonic regime. They
remained in a range such that daily minima were near -4C and the daily maxima near
+4C. The maximum temperature registered in Beaufort Sea was +7.8C on September 7th,
when the southerly flow described above brought milder air to the region. The minimum
temperature was -5C recorded on September 5th, near 75N and 135W.
For the first time in my life (!) I did not see the barograph chart indicate a pressure of less
than 1006 hPA for a period of more than 30 days (almost six weeks, in fact). The
maximum recorded was of near 1033 hpa.
Finally, the winds revived as soon as we left the Beaufort Sea when transiting to Paulatuk
and Kugluktuk. We had a steady northwesterly flow at 25K in Dolphin and Union Strait.
Circulation was forced by a low pressure system that developed over Victoria Island and
slowly drifted SSE to be 120 NM east of Kugluktuk on the 15th. This brought strong
colder northerlies to the region along with rain and snow.
Avos Equipment Operation and Malfunctions
The CGBN AVOS station has worked very well and is fully reliable. Comparisons were
made for the following parameters: air temperature, wind speed and direction, dew point
and corrected barometric pressure. All parameters values were well within limits when
compared with traditional instruments measurements.
The water temperature was obtained from the a functional sea water intake in the aft
science lab. It was favorably compared with sea bucket measurements.
Two problems will be brought to the attention of the Port Meteorological Officer (Andre
Dwyer). I will e-mail him as soon as this report is filed. First, the battery back-up of the
UPS unit (Uninterrupted Power Supply) is not functioning (battery is dead). When it went
down, the AVOS station stopped all measurements and transmissions. It had to be reset.
In order to do so, we have to reset the main breaker in the outside control box. The station
restarted normal function after the adjustment
Secondly, the readings for the H-3 average course of the ship (direction and speed –
DsVs parameter) is always indicating SE at 5K. Erin Clark and my self tried everything
we could think of including (1) ensuring that the ship Gyro was connected properly to the
station and (2) verifying the configuration preset station parameters without success. This
problem is easily “worked-around” by entering the values manually for each
transmission.
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Lastly, this year, we began to use an American weather software called UGRIB (installed
in the Icevu Computer). It has been put to the test at the beginning of my assignment. It
was compared with two long range forecast models. The model is significantly unreliable
east of Point Barrow and for the whole of Beaufort Sea region. Understandable when one
thinks that it was developed for mid-latitudes. This do not constitute a problem given all
other very reliable Canadian and American products available to us for the Arctic
regions.
A weather watch was carried out during the whole trip. Four main and intermediate
messages were transmitted every day including manually entered-observed parameters.
The observations were made at 15Z, 18Z, 21Z and 00Z (day+1). I also kept the barograph
running and a complete record of the observations in the old Meteorological Log (I’m an
old timer, what can I say!)
Ice Specialist Work Station and Equipment
The Icevu computer at the Ice Specialist work station has been working exceptionally
well throughout our trip. The Icevu platform has been working at excellent processing
speed. All installed software worked perfectly well, as expected.
Only one strange occurrence to report: every time a session begins after a long period
with the monitor in sleep mode, the monitor turns itself OFF once or twice when
reactivated. The shut-off last only a few seconds, the it turns back on. After that, it works
perfectly fine! I will bring this problem to the attention of our IT specialist in CIS Ottawa
on Friday.
The printer also works very well. However, in normal printing mode, it uses up ink
cartridges at a very high rate, unless they are of the XL type (extended life). A workaround procedure is to use the printer as often as possible in the draft printing mode.
The Ice Nav station performed perfectly as well. I was surprised at the versatility and
efficiency of the system, particularly when compared to the performance of the IceVu
system when using Polar Stereoscopic Projection imagery. I have outlined the advantages
and disadvantages of the system in our Procedures Manual.
GPS signal feeds to Icevu, Icegg and Ice Nav worked without problems. The Icevu
computer is connected to a UPS which prevents problems when a power failure occurs.
In regards to meteorological equipment and supplies, note the following points:

The barograph works properly and accurately. The clockwork is in good order. Its
felt pen is in good condition and many replacements are found in the
meteorological supplies drawer of the AVOS station desk. There is a sufficient
supply of barograph charts for many months of operation.
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

There are multiple ordinary and SST thermometers in stock. Two working
shipboard psychrometers are found outside, between bridge level and the
observation deck along the stairways both on starboard and port sides (Marine
Stevenson screens). Note that there is a good supply rayon tubing and muslins
(below zero operation). The water reservoirs are stored in the AVOS station desk
drawer.
There is an operational sea bucket at the quarter-deck, starboard side and a spare
in the AVOS station desk drawer.
All ice charts were produced directly from the special work table installed on the port
side of the bridge windows. It is an ideal work place for ship recco’s. Our new pen
computer (Elite Book) was used both from the bridge and during helicopter patrols. As
usual, I experienced a few crashes of the Icegg software, nothing that could not be solved
quickly. When used on the bridge, our new GPS unit works very well when placed on the
window sill. Erin and I ran into one problem with the Icegg software loaded into our new
computers. We had error messages issued when finalizing patrols with certain line
features. The problem was brought to the attention of our IT specialist, in Ottawa. A fix
was found quickly. We only had to reload the Icegg Software sent to us via FTP to solve
the problem for good. I used my pen computer plugged into the AC inverter of the
helicopter on each flight. It worked perfectly. I did not try the pen with solely the battery
pack, but there will be plenty of other occasions to do so.
The new camera provided by EC works like a charm. It is to be noted that the GPS
function on the camera does not work in Beaufort Sea probably due to the weakness of
GPS satellite signals. Numerous pictures were taken during our trip. Many were used
operationally, others to depict ship activities. Some pictures were sent to Sarnia for the
“Monday morning operational briefings”. Many were sent to CIS Ottawa to illustrate ice
conditions in various locations while in operation. All pictures taken during our trip were
“burnt” onto a DVD and left with the captain. They were also transferred to the X:\Crew
McNeil\Marian\Post-Arctic Ship Public Drive.
The Icegg software displayed all daily CIS ice charts correctly and they were
georeferenced.
Most of my idle work time on board gave me a chance to pursue a significant project: I
produced a hopefully useful document intended to regroup all procedures the ISS needs
to be familiar with when on duty on board CGBN. It was produced, finalized, proof-read
and corrected: it has been called the “CGBN ISS Procedures Manual. Such documents do
NOT exist on most of the CCGS ships where ISS personnel are assigned. This procedural
manual contains ISS procedures common to most CG icebreakers, and others that are
very specific to the CGBN. I believe the manual to be exhaustive, concise and useful. In
fact, I am proud of the final product. It has been developed using the framework
established for both the Quebec and St John’s Ice offices by ISS Lucie Thériault and ISS
Éric Vaillant. I also need to mention the invaluable support received from ISS Erin Clark
in the proof-reading and improvements to the manual from a technical writing point of
view. It will be tool for any ISS with limited experience coming to the CGBN. The core
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of the manual was developed when I wrote equivalent documents on the CCGS Des
Groseilliers and CCGS Sir Wilfrid Laurier, last year. It will be presented at the next semiannual ISS meeting in November. It will also be an essential instrument to abide by the
audit rules dictated by the ISO9000 program which EC CIS come under
Satellite Imagery and Quality of Cis Ice Charts and Analysis
We received numerous satellite images (Radarsat 1-2, Modis and NOAA images) issued
by CIS in Ottawa. We also received (thanks to the work of Caryn Panowicz) the evening
ascending passes from the National Ice Centre in Washington. This is one of the definite
advantages of working in collaboration with US agencies. The area coverage was
absolutely adequate and timely to meet our operational needs. This is an exceptional and
commendable performance by CIS Ottawa!
The RSAT-2 images were of particularly good quality. I need to mention the excellent
planning work done by ISS Erin Clark and Darlene Langlois from the CIS, to prepare the
imagery orders for the UNCLOS voyage. There has been only TWO missing passes, due
to the long imagery processing delays at the Alaskan Receiving station. These delays
were also due to lower priority assigned to some image orders. None of these factors
negatively impacted operations.
I want to mention the collaboration provided by the people of the CIS in regards to
adjustments made to ice products (daily ice charts) in accordance with our observations
and for the promptitude with which our FTP standing order adjustments were made when
requested. Lastly, we found the special bulletin FICN00 produced specifically for the
CGBN Beaufort Sea operations to be useful when outside of marine forecast regions.
Communications
The Telesat Internet service has worked very well throughout our trip (Username :
iceobserver, password : iceobs). In a few instances, the signal was interrupted because of
ship course, but this was never truly detrimental to operations.
Access to this type of communication significantly simplifies the work of the ISS. The
Internet heavy use during peak periods slows data access significantly. However, all the
major downloads were done outside peak hours (ie. very early in the morning or midafternoon).
I only had to turn to SAT-B communications on twice during the trip and it worked well
in both instances. The procedure to follow in case it has to be used is in Appendix S of
the CGBN Procedure Manual.
When the ship passed north of 78N, the Iridium signal replaced the weakened Telesat
signal. Iridium communications worked beautifully.
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Phone communications and the Wireless link between CGBN and NEPP worked very
well whenever the CGBN and USCGC Healy were within the 2 NM range.
Accomodations
I was assigned the cabin normally used by the ISS located on the “boat and flight deck”.
The CCGS Louis S. St-Laurent is one of the most comfortable ships when it comes to life
on board. The cabin is very spacious with sufficient storage space. The furniture is in
very good condition. Washroom and laundry facilities are close by. It is also very well
appreciated to have Internet hook-up in the cabin. Only one element has not been
working: the TV set died on the first few days I was on board! Not a problem, because
both the officer’s and crew lounges have top notch TV systems.
Support of Bridge Officers and Crew Personnel
Firstly, I must emphasize the excellent collaboration obtained from all CCGS Louis S. StLaurent bridge officers and ship personnel during my stay on board. They all and always
demonstrated a high level of professionalism. All of them contributed to the success of
my work on board. My stay on your ship enabled me to add-on to my own experience
and knowledge as an ISS. In addition, all exchanges were always upbeat and friendly.
Secondly, I want to express my most sincere appreciation and thankfulness to the CCGS
Louis S St-Laurent crew and the admiration I have for their exemplary teamwork
approach. Every member of the crew seems to be very conscious that he/she is part of a
larger team that must work with as few problems as possible so that and efficient
operation of the ship is possible. I respectfully ask you, the captain, to extend my most
sincere thanks to all crew members. They made my integration to the team easy and, in
many instances, were of great help to facilitate my work on board.
The weather and ice briefings were informally made in accordance with the needs of the
commanding officer or any other navigation officer. Aviation briefings were also given to
the helicopter pilot every time a flight was planned or whenever flight operations were
carried out. Every night at 19h00, a complete ice and weather briefing was given to the
science team in the ship’s boardroom. Other briefings were given informally whenever
requested. My work practices ensure that all necessary information is made available
immediately, on demand, and at all times up-to-date when requested. I am absolutely
conscious that Ice Service Specialists are at the service of the CCG, and, consequently,
must maintain the highest standards of efficiency at work to support the ship’s operations.
Recommendations and Actions
As mentioned above, concerns about the operation of the AVOS station will be brought to the
attention of the NF Port Meteorological Officer
133
The AVOS UPS (uninterrupted Power Supply).unit batteries must be replaced (PMO will be
informed).
A DVD to be left with the captain was prepared. It contains: (1) all pictures taken by the ISS
during the trip, (2) the climatology data regarding the Beaufort Sea and Western Arctic for the
current year, (3) the ISS trip report and (4) the ISS Procedures Manual.
All the ice and weather information used for briefing purposes to the science team was left with
the science team leader, Dave Mosher, in its electronic form.
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All the data burned onto the DVD was also placed in X:\Crew
McNeil\Marian\Post-Arctic Ship Public Drive under the file folder CIS ISS
Summer 2010.
I produced the “CCGS Louis S. St-Laurent – ISS Operational Document –
Procedures Manual”; a comprehensive procedures manual to be used as a
reference for all ISS duties performed onboard. The M is subject to the approval
of François Choquet ( AWIR - Chief – Exterior Services) and André Pelland –
Marine Operations Manager
Erin Clark was responsible to submit recommendations to improve the working
environment in the ISS office. In addition to her suggestions, I would like to
mention two important elements: (1) The lighting in the room constantly reflects
on the computer keyboard which is annoying and (2) there should be more free
space between the ISS work position chair and surrounding desks to ensure easy
movement in and out of the work position.
I would also recommend that, in future voyages, the representative of the NIC
(US Ice Specialist) would be a person that manifests motivation and participation
in the familiarization activities related to the work and tasks devolved to the ISS
on board a CCG ship. It was not the case with the person assigned to the task this
year.
Acknowledgements
My stay on board the CCGS Louis S. St-Laurent has definitely been very enjoyable. I
would like to extend my most sincere thanks to all crew members and more particularly
to the captain. It has been very easy to become a member of the ship’s team and my work
has consequently been made that much easier. I truly enjoyed my assignment on the
“Louis” and hope to be able to return for duty in the near future.
Very respectfully,
________________________________
Bruno Barrette
Ice Service Specialist
Canadian Ice Service
134
Ottawa
CC :
François Choquet – AWIR - Chief – Exterior Services
André Pelland – Marine Operations Manager
Canadian Ice Service
Ottawa
135
Appendix A
Daily and Weekly Logs
136
Chief Scientist Daily Log
August 4th. (Wednesday) (JD 216)
Charter flight St. John's to Kugluktuk via Iqaluit.
Met Jon Childs and MMO's in Kugluktuk....all scientific personnel on board by late
afternoon.
August 5th (Thursday) (JD 217)
Kugluktuk. Ship's Captain decides to spend the day at anchor for crew familiarization
(30 new ship staff members).
August 6th (Friday) (JD 218)
Weigh anchor at 12:30 Central Time and steam towards Beaufort Sea. Delays in US
permissions to survey in the US EEZ have forced us to modify our plan and to conduct
surveying in Canadian waters first. The only open areas where we can conduct single
ship seismic operations is in the shallower portion of the Beaufort Sea - at our planned
FGP tie lines. 2 days steam to arrive at survey area.
August 7th (Saturday) (JD 219)
Steaming
Preparation of equipment
Clocks went back 1 hour to Mountain Time zone.
August 8th (Sunday). (JD 220)
Planned for early morning arrival for commencement of survey. Captain would not
permit CG crew to commence until 08:00. Commenced deployment by 0830. 3.5 kHz
tow body and streamer deployed. Significant rigging involved in getting the shallow tow
version of the airgun array - very time consuming.
- Late morning (1130) ready to commence. Streamer not functioning and Long Shot
firing unit not working. Swapped out the firing unit and brought the streamer on board.
Replaced repeater unit and deck cable and redeployed. By mid-afternoon, all functioning
and commence surveying.
2200h Port compressor fails (same one that always fails!). Replace with Stbd compressor
and back operational.
August 9th (Monday) (JD 221)
Continued surveying Canadian Beaufort shelf to slope region throughout the day and
night. Compressor 1 repaired but still leaking fluid. Still running on #2.
August 10th (JD 222)
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Ceased survey on Line 3 at 0830. Conducted signature test of shallow tow array
and then pulled gear on board. Switching over from shallow tow array to ice
array before US EEZ work. Gear on board by about 11:00
-Steamed to meet up with Healy. We met up at 17:00 local. Captain, Jon Childs
and I flew over to meet with Brian Edwards, Captain Rall, Dale Chayes etc.
-Flew back to LSSL by 2000h
Still no US IHA approvals which means we cannot start surveying in US EEZ.
Personnel transferred including Captain Bourdeau, Erin Clarke and David Street
over to Healy. Sarah, kwasi (US MMOs) and Caryn Panwicz (US ice observer)
came over to Louis from Healy.
August 11th (Wednesday) (JD 223)
 At 6:20 am (Pacific time) discovered that a crewman had injured his hand and we
are heading to Tuktoyuktuk to send him ashore for medical attention. The cut is
deep and requires stitches. Steam all day to Tuk. At 1745h, helicopter deployed
to take him to Tuk. Helicopter returned at 2015 and heading back to US EEZ
 Ironically, US IHA approval arrived this afternoon, at about 1500h
 Gang has rebuilt the ice seismic airgun arrays and are ready to deploy as soon as
we are back on station
 Comparison of measured source signatures and those of the Gundalf model are
excellent.
August 12 (JD 224)
 Steaming 17 knots most of the day towards first line in the US EEZ. Arrived at
1430 and began deploying seismics. Gear in the water and firing by 1600h. Ice
configuration. Start of line 6 shortly after. Fog nearly prevented startup of array.
Response to marine mammal observation is significantly more complex in US
waters. In addition, startup requires 30 minutes of 2.5 km visual.
 Guns and streamer working well and deployed first sonobuoy at 2000h.
August 13 (JD 225)
 2nd deployment of a Sonobuoy. Noticed interference on the sonobuoy records. It
seems as though we are picking up the shots from the Bos Atlantic - last position
was 79 29N and 139 35W at 1600UTC on August 12...about 170 nMi from us.
 Streamer started to show water egress through the day...finally about 1500h she
shorted out. Rigged a 150 cu in gun to deploy to keep shots firing in the water in
order to avoid shut down and start up procedures in US waters. Brought the gun
sled aboard and replaced the first repeater unit at the tow point...that fixed the
problem and we redeployed...took a couple of hours. Back operational by about
1700h.
 2000h first teleconference call with Healy on voice-over IP.
 Monster bash that evening... Polar Bear sighting - mother and cub long way off.
August 14 (JD 226)
138
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0400 got called from Borden...streamer died again. Seems we were stuck in ice
and screws were revved for over 20 minutes...might have caused the leakage. We
roused the crew and brought in the sled and streamer (deployed the small 150 gun
first). Hand-hauled the streamer and got it up to the helideck. Attached the stbd
streamer to the port gun sled and redeployed. Back operational by 0730.
Operating with port guns and stbd streamer running all down. completed first US
EEZ line and turned to head south on the second line. Data quality is excellent.
Still trying to discern source of interference on the sonobuoy records, but the
quality of the data is still excellent.
August 15 (JD 227)
 Heading south on 2nd US EEZ line. making good progress. Position is 73º
08.04759N, 147º 51.12136W at 0730h Pacific time
 Fog and low surface fog with brighter skies overhead.
 Weather worsened as the day progressed. High winds and seas as we got out of
the ice front - affecting data quality
 Healy forged ahead to pick up our crewman and fuel filters from Barrow. They
acquired bathy and chirp during their transit along the same line.
 ~2100h #2 compressor, radiator failed...switched back to number 1. No more
spare radiators. Not sure why they are failing
August 16 (JD 228)
 Rough night - heavy sea swell hitting us broad side. Woke in the morning to find
us 5 miles off track and heading in the wrong direction. During the night, Captain
ordered to alter course to head more into the sea. That is fine, but I, nor the
watch, was notified. We terminated the line in the morning without completion,
since we were so far off line by then anyway. Our stbd compressor had a shaft on
the belt wheel loosen. Pulled in the seismic gear at 0800 PST to also take a look
at the streamer...for some reason it is giving negative readings on the current.
 Blue skies and swell diminished as we got closer inboard and ice dampened the
sea swell. Scattered multiyear ice pieces all around. Nice and calm actually
 Healy in Barrow, have taken our man aboard but are waiting for the fuel filters in
the morning flight - they did not arrive last night.
 Started line at the south to head north (westwardmost line of the US EEZ survey)
at 1100 PST = line 11. Deployed Sonobuoy 8.
 As we proceeded north, we encountered long heavy swells again.
 Late in the day the seas continued to drop.
 Learned at about 2200h that the Healy had picked up our fuel filters and is now
proceeeding to intersect us at speed
August 17 (JD 229)
 Swells continued to die down through the night. Morning fog burned off to be a
beautiful day. Seismic system working wonderfully and guys fired up the Port
compressor to test their patch job on the radiator.
139
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Healy reached us just as we entered the ice pack at 1200h, just in time. Once
through the edge, the ice is scatter 3-4/10ths of mostly old multi-year. Winds
calm and seas calm.
helicopter effected transfer of crewman and filters from Healy to Louis and took
the ice pik up for a recon flight.
Great Day
August 18 (JD 230)
 Turned on to line 12 heading to NW towards Northwind ridge at about 0700h and eventually picks up Art Grantz' old line 93-11
 US Mammal observers returned to Healy
 Helo went on a recon flight
 Bruno (Ice Pik) spotted a large flow along line and advised Captains to veer
around the flow....took us >5 miles out of our way - Without telling me - I was
quite upset about it. Talked to the Captain that I should be involved in these
debriefings from the ice pik.
 Issue arose with respect to speed in water vs speed over land. Captain upset that
John S. spoke directly to the mates, which is absurd - our watchkeepers have to be
able to speak to the mates about these issues. I think I've sorted that out with the
Captain.
 Repairs to the port compressor continue - trying to rig up a water cooled heat
exchanger.
 Dale and Johnny want to split their shifts to 4 and 4...
August 19 (JD 231)
 Continued surveying line 11 - 12 but 4 miles prior to end of line (~1500h), the
stbd compressor blew a seal on an oil line and oil sprayed everywhere. Had to
shut down and clean up and repair. Streamer was also acting up with spikes in the
leakage display values. We pulled the gear and steamed for waypoint 19 to 20
that brings us east out of Northwind ridge...large pool of open water there to
deploy. We broke ice for the Healy for the transit. 1830h we are back in
operation on Line 13, due west off of Northwind Ridge.
 Spoke to Jacob w.r.t. priority lines. His priorities are the far north lines, so we will
transit to get to those. Only ~13 days left of Healy and Louis joint time. Drafted
a plan to get us up to there and back by Sept. 3.
 I took two of the mates (Adam and Albert) on tour of the quarterdeck so they
could see what we are dealing with and why the need for speed in water.
 Polar bear sighting ~1700h
 evening science meeting at 1900h as per usual
 evening telecom with Healy at 2000h as per usual
August 20 (JD 232)
 0200h PST, gear had to come in because of leakage into the streamer. We cannot
seem to solve the issue of leakage at the first repeater behind the sled. We
reconfigured the bracket a bit, put it back in the water and will think about more
140
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drastic changes during the next transit. Back in the water and operational by
0400h.
Helo ops in afternoon. Walli and Jon Childs over to Healy. Ice observation with
Bruno, Erin and Jason (latter 2 from the Healy).
Jon Biggar tried out his instrumentation from the Helo after supper.
Ryan tells me about a near fire in the compressor...yikes!
Equipment working well...significant amount of low fog, generally light ice
conditions to open water.
August 21 (Sat) (JD 233)
 Completed line 14 about 0730 - continued line until 0800h, then brought all gear
on board and took an SVP station - Healy did a CTD station nearby
 Transit for the rest of the day - mostly through decayed first year ice... lots of fog
but little wind.
August 22 (Sunday) (JD 234)
 Arrived at Waypoint 21 on Northeastern portion of Northwind Ridge at 0330h.
Deployed gear to run Line 15 and were underway by 0430h. Ice light and rotten
but freeze up appears to be starting - beautiful clear day.
 Ice cover nearly continuous through day, although apparently thin.
 At ~1430h, ice pack appeared to start to move and track behind Healy closed in
quickly. Louis wasn't close enough and pack closed until we got stuck. Helo
operations on personnel transfer - Healy pulls ahead and stops to take on Helo too far ahead and stopped too long. Louis had to slow and lost momentum.
Beautiful sunny day with no wind.
 1800h all gear back in the water and continuing line (now line 16).
August 23 (JD 235)
 10/10 ice cover - clear morning with some surface fog. All gear worked
throughout the night.
 #1 Compressor (stbd) stopped working at 0930h. Don't know why...fired up #2
but it took some time as the engine room had to supply fresh water to the juryrigged heat exchanger. Lost ~10 - 15 minutes of shots...
 Pull gear at 1130h; 1230, on our way north...
 John Shimeld gave a talk on seismics
 2115h Ship's port propeller problem...shaft bearings went dry (no oil) and wore
out, as well as pads . Captain estimates 2 days minimum to repair. I sent the
Healy on to the Seamount to core and we will reassess the situation in the
morning. 79º 52.17N, 140º53.10'W
August 24 (JD 236)
 Awaiting repairs to port propeller shaft bearings
 ~2100h testing underway
141
August 25 (JD 237)
0100h started transit
 Decided to cancel northern survey line (south to north) up onto Alpha Ridge.
 Proceeding to east side of Nautilus Ridge to survey west to east, across to north
side of Sever Spur to tie in to bathymetry point soundings.
 Occasional stops to clear filters on propeller shaft oil
August 26 (JD 238)
 0300h met up with Healy at Waypoint 28 (east side of Nautilus Spur). Engine
room cleared filters again, then gear in the water and operational by 0440h. SOL
17.
 Stuck twice within the first couple of hours! We did not get stuck once last year.
 Gradually, the bridge(s) seem to be realizing what needs to be done to maintain
headway. Unfortunately, they used the centre shaft a few times, and now the
seismic sled has a few twists in it. We've been stuck only once more since this
morning.
 Continue to survey in relatively heavy ice conditions, however. Made about 50
nMi since start of line to midnight.
August 27 (JD 239)
 0150h got a call from John S...seems only 8 channels are being acquired. Perhaps
one of the A/D modules. John rebooted and it seemed to recover all 16 channels,
but then failed shortly after. Continued surveying anyway, acquiring only the 8
aft channels.
 0630h, decided to pull in the gear as there was a large open pond nearby. Made
ties to seismic lines LSL09-21 and 23
 0830h gear on board with the streamer wrapped around the tow sled...
Position 81º 46.90'N, 128º 20.55'W; 98 nMi along line.
 Took SVP and Healy took a CTD.
 Changed tow sleds...Ready to redeploy gear at 1115h; Captain orders to wait until
1200h, after lunch.
 Gear redeployed at 1230h - Line 18
 Streamer lasted only about 2 hours when it shorted out and we brought it back up
... changed out the fore repeater unit and redeployed.
 No success...streamer still giving high current....recovered entire array and
swapped streamers
 Redeployed at about 1800h. Again, streamer read fine on the deck and for a few
minutes in the water, then leakage went through the roof!
 Recovered gear about 2000h and finished line as a multibeam/chirp line - so we
broke ice for the Healy
August 28 (JD 240)
 Breaking ice all day for Healy - heading to tie in Borden Island spot sounding
profile. Making about 4-5 knots only. Heavy ice but not unmanageable.
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1530h Captain informs me that we may have a med-evac situation!
1630h Captain informs me that we are on med-evac
August 29 (JD 241)
 Continue transit on med-evac - only made about 45 nMi last night, through heavy
ice.
 Still on Sever Spur heading almost due south...not sure why we didn't back track
and head west to easier ice.
 Ice conditions improved through the day.
August 30 (JD 242)
 Transit to Tuk
 A Healy person injured their hand and was transferred to the Louis for med-evac
to Tuk.
 Transit alone - Healy split off to go to core sites.
 Our patient (Winston) is doing well. Will go home out of this and not to hospital
or Dr.'s care!
August 31 (JD 243)
 Out of ice by mid-morning
 Helicopter departed for Tuk with patients at 17:30, LSSL continued steaming
toward Tuk
 Helicopter back on board at 21:30
 Engine Room needed some time to change filters etc on propeller shaft bearings
 Underway for McClure Sound Waypoint 37 at 0145h PST (sept 1)...why the
delay?
September 1 (JD 244)
 Underway to Waypoint 37 off of McClure Sound at 0145h, Travel around ice
margin up along Banks Island
September 2 (JD 245)
 Transit still to Waypoint 37. Busting through nasty ice this morning...much
improved by afternoon.
 Arrived WP at 1730h; streamer deployed and operational @1900h; line 19
 Fly-over from US Coast Guard Aurora
September 3 (JD 246)
 Completed line 19 at 2130h and turned south on line 20
 John informed me we have 3rd multiple interference on Line 19 data - ouch!....so
much effort to get here.
September 4 (JD 247)
 Continue Line 20
 Healy breaks off at 1200h
143
September 5 (JD 248) Sunday
 Continuing line 20, all working well (knock on wood)
 Weather clear, some fog. Ice - 9/10s but old and rotten. Some difficult spots but
OK for one ship.
September 6 (JD 249)
 Continuing south on line 20. 2nd year and multiyear ice, rotten and lots of holes
and no pressure. Bridge still steering around the ice flows as much as possible.
 ~1003h PST Flew out in chopper and deployed a sonobuoy ahead of the ship to
get both refraction limbs. Requested vessel steer a straight course for the position
and deviate as little as possible.
 Reviewed these sonobuoy data - unfortunately, the antenna does not look forward
very well, so data quality is poor on the approaching limb, but fantastic on the
sail-away limb.
 Shut down and started new line in order to dump cache on seismic acquisition
system. Line no. 21, but still line heading south.
 Weather worsening through the night. Winds up to 25 knots
September 7 (JD 250)
 Continuation of line 21/22
 Winds 25 knots gusting to 30 under gloomy skies. Wave height probably 2 m.
Lots of noise on seismic records. Skies improve in pm but still rough seas.
 Turn eastwards ~1530h PST to tie to FGP line to the east. Leaving gear in the
water because of significant wave height ???? Captain wanted us to pull gear
early, I said it was fine to be left out.
September 8 (JD 251)
 Continuing Line 23 eastward. Wave height down in the am...supposed to
continue to drop. Nice blue sky.
 Significant wave heights still by late pm, no sign that wind is abating.
 Conducted a helicopter sonobuoy drop (#29) ahead of the vessel along this line.
We mounted a forward looking antenna and at 0930h went out with a sonobuoy
and deployed. We digitized the forward and aft antennas as separate channels on
the GSCDig. Seems to be working although the GSCDIG is having problems
keeping up with the sample rate??? Looks like a trigger jitter....ugh!
 tied to FGP line 87-1B, ~2300h Turned on to Line 24 heading to NW...
September 9 (JD 252)
 Deployed sonobuoy 30 ~ 0100h,
 Continuing line 24 to NW, deployed a sonobuoy ahead of the ship with the helo at
10:53
 Spotted sonobuoy to the port at 14:30
 GSCDig was not able to record 2 channels with such long record lengths.
 Late evening - fog encountered, a sign that we are approaching the ice edge.
144
September 10 (JD 253)
 Started to encounter light ice in very early morning
 Gun number 1 acting up a bit - perhaps water or crude in the firing chamber?
Clears and then acts up again - firing on manual when it acts up.
 After lunch, deployed a sonobuoy from the helo (John S and me) - lots of fog.
First sonobuoy didn't come up (maybe under ice), second one worked. deployed
at 1337h PST
 Passed Sonobuoy about 1700h PST
 Ice thickening up a bit as we proceed NW...rotten and still feasible by one ice
breaker.
September 11 (JD 254)
 Final day of seismic operations.
 Gear continues to work - on to Day 9 for this deployment - incredible.
 very light ice this far to the west.
 1210h seismics off; 1230h all gear on board, 111460 shots in total
 SVP station
 1500h All Science Operations complete and we're heading to Paulatuk.
September 12 (JD 255) Sunday
 Steaming to Paulatuk
September 13 (JD 256)
 Dropped Jonal Nakimiyak, Dale Ruben, John Ruben and Nelson Ruben off in
Paulatuk via helicopter 0830h PST
145
NRCan Weekly Reports
Weekly Report, August 9, 2010
August 4th. (Wednesday)
Charter flight St. John's to Kugluktuk via Iqaluit.
Met Jon Childs and MMO's in Kugluktuk....all scientific personnel on board by late
afternoon.
August 5th (Thursday)
Kugluktuk. Ship's Captain decides to spend the day at anchor for crew familiarization
(30 new ship staff members).
August 6th (Friday)
Weigh anchor at 12:30 Central Time and steam towards Beaufort Sea. Delays in US
permissions to survey in the US EEZ have forced us to modify our plan and to conduct
surveying in Canadian waters first. The only open areas where we can conduct single
ship seismic operations is in the shallower portion of the Beaufort Sea - at our planned
FGP tie lines. 2 days steam to arrive at survey area.
August 7th (Saturday)
Steaming
Preparation of equipment
Clocks went back 1 hour to Mountain Time zone.
August 8th (Sunday).
Planned for early morning arrival for commencement of survey. Captain would not
permit CG crew to commence until 08:00. Commenced deployment by 0830. 3.5 kHz
tow body and streamer deployed. Significant rigging involved in getting the shallow tow
version of the airgun array - very time consuming.
- Late morning (1130) ready to commence. Streamer not functioning and Long Shot
firing unit not working. Swapped out the firing unit and brought the streamer on board.
Replaced repeater unit and deck cable and redeployed. By mid-afternoon, all functioning
and commence surveying.
2200h Port compressor fails (same one that always fails!). Replace with Stbd compressor
and back operational.
146
Weekly Report August 15, Day 11
At 1515h, our position is 72º 44.67N, 149º04.38W.
August 8th, Commenced surveying on the Canadian Beaufort Slope and outer shelf with
open water tow configuration and Chirp system. After start up problems we conducted
the survey until 0830 on August 10th. Rendezvous with Healy on August 10th (evening)
for face-to-face meetings between Chief Scientists and Captains on the Healy.
Transferred personnel. Steamed toward first waypoint in the US EEZ, despite awaiting
US approvals. August 11, 0620h learned of an injured engine room crew member. We
steamed back to Tuktoyuktuk to take him to shore via helicopter. US approvals came in
at 1500h. Helicopter returns to LSSL at 2030 that evening and we head back to US EEZ.
Because of significant ice, we switched the seismic system back to the ice-tow array. It
was a major effort to change over.
1430, August 12, arrive at first waypoint in US EEZ and immediately commence seismic
operations. Some difficulty in startup because of fog and US requirements for mammal
observation (2.5 km for 30 min. prior to startup). Eventually manage to start seismic
operations and survey northwards on first leg of Line 4. No ice until northern half of the
line, with increasing density northwards. Significant amounts of old ice around the edges
of the pack. Two incidents of water egress into the first repeater unit of the streamer
requiring recovery and causing delays. One incident resulting from LSSL stuck in ice
and needing to increase prop revs. Now heading south on second leg of the US EEZ
survey pattern. All working well and data quality is generally excellent. We are now in
open water with significant swell, however.
We are significantly behind schedule on our initial survey plan. Modifications are being
considered to lines off Northwind Ridge and to remaining survey patterns.
TOTALS
805 line km seismic data (325 km with open water configuration in Canadian waters)
22319 shots
6 sonobuoy deployments
Healy completed multibeam survey pattern in the disputed zone
147
148
Weekly Report August 16 - 22, Day 12-18
At 1800h (PST), LSSL position is 78º 23.42N 150º 45.26N
Completed the lines in the US EEZ by August 17. Some weather issues causing noisy
data and off track positions on one line, but otherwise, data quality is excellent. After
completing all planned lines exiting the US EEZ, we deployed the US mammal observers
back to Healy. After significant delays due to customs in Anchorage, Healy picked up
our crewman and ship's fuel filters in Barrow and delivered them to us on August 17 caught up with us just as we entered the ice pack. Very light ice conditions initially,
mostly scattered decaying multiyear ice. Completed two "modified" dip lines into and
out of Northwind Ridge. Excellent data quality. Some issues with streamer leakage - all
focussed on the foremost repeater unit - where it attaches to the sled. Port compressor
blew a second first stage heat exchanger and is inoperable (no further spares), although
the guys eventually came up with a fix using one of the ship's water cooled heat
exchangers. It is not ideal as the ship has to use her fire pumps in order to run sea water
through it...so it is an "emergency" spare only. On August 19, the starboard compressor
blew an oil seal and needed repair, terminating one of the NW Ridge lines just before end
of line. The port compressor was not yet functional, so while repairs were effected we
transited to second line on NW ridge. We are now on the third line in the north of NW
Ridge. Ice is continuous but not thick. We managed to get stuck in the ice and had to pull
gear. Presently shut down for helicopter operations and supper!
Totals
4,400 ship's track (bathymetry)
1,785 line km seismics
56000 shots
16 sonobuoy deployments
1 SVP station
15 xctds
August 22nd - August 29th. Louis S. St-Laurent Weekly Report
August 22nd, working on a line running NE off of Northwind Ridge toward the centre of
the basin, ice became thicker and started closing in, causing us to get stuck a couple of
times. By Monday, we pulled the gear to head to the northern extremity of the survey
area to accomplish our objectives there. 36 hours were lost due to propeller bearing
problems on the port shaft of the Louis. Healy went ahead and cored on the Seamount recovering 4.93 m of core. By Tuesday, August 25th at 0100h we were in transit again
toward the north, but this delay cost us the northern line. Frequent stops to clean oil
filters on the propeller shaft. By Thursday, August 26th, we met up with the Healy and
by 0440h we started surveying from Nautilus Spur towards the east to intersect the north
side of Sever Spur. Heavy ice, Louis got stuck a couple of times as well bridge applied
149
the centre shaft which causes our towed seismic gear to tangle. It still was operational, so
we left it deployed. Eventually, however, the streamer failed - first acquiring only 8
channels, then complete loss of data - upon recover it was wrapped around the gun array.
Ongoing issues with the streamer caused us to switch streamers, but it would not work
either. After numerous deployments and recoveries, we decided to pull in the seismic
gear and multibeam the remainder of the line while we figured out the issues with the
gear. We broke ice for Healy. We made the first sounding point north of Sever Spur
(spot soundings from this spring's ice camp), when the Captain informed me that we had
a med-evac situation (1520h PST, August 28th). All scientific operations ceased and we
are presently on transit to Tuk to deploy Coast Guard crewman.
Total navigation track
Total seismic
furthest north
5.223.30 km
2,206.40 km
82º 33'
August 30th to September 05 Louis S. St-Laurent Weekly Report
Took on an injured engine room tech from Healy (hurt hand) on August 30 as part of our
med-evac to Tuktoyuktuk. Healy then broke off to go to a basin core site. Completed
med-evac to Tuktoyuktuk on August 31. Helicopter was back aboard by 2130h PST but
engine room needed to conduct work until 0145h PST on Sept. 1. Then proceeded to a
way point on the north side of McClure Sound, travelling around the ice margin next to
Banks Island. Operational again on Sept. 2nd @1900h PST; US Coast Guard Aurora
aircraft did a fly-over that evening. September 3rd we completed the westward line out
of McClure Sound to tie into line 2009-31 and turned south to complete an easterly
transect line through the 2007 margin lines. Some compressor problems but nothing
debilitating. Healy broke off to head back to Barrow on August 4th. She completed one
core in the basin and surveying the 2500 m contour off McClure Sound while we were on
the med-evac run. Still on this southward line that will tie into MacKenzie lines acquired
at the start of the survey by Tuesday morning.
Position at 14:23:08Z 73º 04.81'N, 136º 45.68'W
Total navigation track 8,354 km
Total seismic
2,551 km
Number shots
82041
150
Green = 2010 Seismic tracks, White = previous seismic tracks
Black = Ship track
151
Weekly Report, Sept 6-Sept 12, 2010
Completed the southward line to tie into Beaufort shelf lines from the start of the
program, and to FGP line 87-3. The weather and sea state got rather nasty so we elected
to leave the gear in the water and conducted a transect line to the east across the front of
the delta. By Sept 8th, the weather was down a bit. We started a line heading northwest
that ties from FGP line 8701B out to our main grid in the center of the basin. At the
northern half of this line, we were back in ice, but light enough to work through with one
ice-breaker. We completed this line on September 11 and ran a short line to the SW that
crossed the gravity low structure. By 1210h PST on September 11, all seismic gear was
brought in to end the program. This deployment lasted 9 days - a new record. We
completed an SVP station and then started making way to Kugluktuk by 1500h.
28 days on task
9600 km track
3673 line-km of MCS data
111460 shots
34 sonobuoy deployments
33 XCTD stations
14 XBT stations
3 SVP casts
61 Spot soundings
152
Canadian Hydrographic Services Weekly Report
Jon Biggar
UNCLOS – CCGS Louis S. St Laurent 2010
Highlights: departed Burlington, bathymetry/seismic program started
Weekly Summary: Aug 3 to 8
Aug 3 Tuesday – staff traveled to St John’s, overnight for crew change flight next day
Aug 4 Wednesday –staff departed on crew change flight to Kugluktuk, departed shortly
after 7 AM, 6 hour flight with stop over in Iqualuit (1 hour) for flight crew change and
fuel, arrive at Kugluktuk midday
Aug 5 Thursday – started computers, training, ship orientation for staff
Aug 6 Friday – boat and fire drill, departed Kugluktuk, problems with deep water SVP
(sound velocity probe). Seems a wrong config file was sent with the unit after company
service and calibration, the unit will works HyperTerminal, Tony has been a great help
with this problem
Aug 7 Saturday – started setting up helicopter equipment, problems with Novatel
communications over ship network, problems with NovAtel GPS receiver /BackPack
communications also, both were resolved
Aug 8 Sunday – sound operations began (24/7), seismic operations had equipment
problems but were repaired and operations began
Plans: Continue seismic / bathymetry survey operations 24/7 and rendezvous with Healy
mid week
The Plan: red lines – proposed survey lines (highlighted area is the present work location)
white lines – previous year’s survey lines
153
154
UNCLOS – CCGS Louis S. St Laurent 2010
Highlights: Two ship operations CCGS Louis S St. Laurent and Coast Guard icebreaker
Healy has commenced, bathymetry/seismic program underway, 2000 line kilometers of
bathymetry collected to date.
Weekly Summary: Aug 9 to 15
Aug 9 Monday – sounding and seismic ops, minor problems with Knudsen sounder,
operating 3.5 kHz and 12 kHz Knudsen sounders
Aug 10 Tuesday – stopped seismic after breakfast, calibration of air guns, remove all
gear, heading for Healy, continued sounding ops with 12 kHz Knudsen sounder,
deployed XCTDs, General Dynamics ruggedized laptop which is used for the
Expendable probes has a boot file error, unusable, replaced with laptop used for Iridium
phone email system, staff was exchanged with the Healy, SVP plus probe is now
operational, the time/date was set up wrong in unit which was conflicting with the other
the parameters
Aug 11 Wednesday – sounding ops, enroute to start of line when one of the engineers
badly cut his hand, returning to Tuktoyaktuk for a medavac, helicopter a shore late in the
evening
Aug 12 Thursday – sounding ops, returning to start of line, deployed seismic gear shortly
before dinner, seismic ops started
Aug 13 Friday – sounding and seismic ops, deployed the XBT in the AM, started into the
ice with Healy escort, about 4/10s ice, problems with streamer in afternoon, repaired,
redeployed, XCTD and XBT deployed, prepared SVP plus probe for winch ops
Aug 14 Saturday – sounding and seismic ops, problems with seismic equipment early
morning, redeployed other streamer and continued operations, 2 XBTs deployed
Aug 15 Sunday – sounding and seismic ops, moving south out of the ice approximately
13:00 local, 2 XBTs deployed
Plans: Continue seismic / bathymetry survey operations 24/7 with the Healy, expect to be
at end of line Monday morning turning north, survey plan is being modified to account
for lost time.
Sketch: Red lines are the proposed survey lines; yellow highlighted lines are completed
to date.
155
156
UNCLOS – CCGS Louis S. St Laurent 2010
Highlights: Two ship operations CCGS Louis S St. Laurent and Coast Guard icebreaker
Healy continues, bathymetry/seismic program underway, To date 4736 line kilometers of
bathymetry has been collected along with 24 XCTD, 14 XBT, 2 deep-water SVP cast and
23 spot soundings. Helicopter logged 4.4 hours of flight time. The helicopter spotsounding ops were hampered most of the week because of weather conditions. Saturday
evening the surveying was suspended and presently the Louis S St Laurent is heading for
Tuktoyaluk for Medavac of a crewmember. Sounding operations continue enroute.
Weekly Summary: Aug 23 to 29
Aug 23 Monday - sounding and seismic ops, breakdowns with seismic air compressor,
recovered seismic gear at noon, Louis is escorting Healy sounding ops continues,
attempted helicopter spot sounding but problems with the larger Airmar 12 kHz
transducer, switched to smaller 12 kHz transducer, noticeable volume difference in
pinging, CDU Novatel software froze, restarted and reset port, Monday night the
propeller shaft bearings failed, ship down for repairs, Healy continued on
Aug 24 Tuesday – stopped overnight and most of the day for ship repairs, resumed
sounding ops approximately 10PM heading north
Aug 25 Wednesday – sounding ops, modified survey lines heading for east/west line to
rendezvous with Healy at start point, helicopter flight with 11 spot soundings
Aug 26 Thursday – deployed seismic gear approximately 4 AM, ships now into heavier
ice, helicopter flight with 12 spot soundings, standby for weather for second helicopter
flight
Aug 27 Friday – sounding and seismic ops, several problems with seismic streamer,
recovered and deployed numerous times during the day, left on deck for repairs, SVP cast
to 3600 metres, Louis escorting Healy continuing line to the east into 2500 metre contour,
standby for weather for helicopter spot sounding ops
Aug 28 Saturday – sounding ops, Louis escorting Healy, turned towards Tuktoyaktuk
approximately 18:00 for a medavac of a crew member, standby for weather for helicopter
spot sounding ops
Aug 29 Sunday – sounding ops in heavy ice, both ships enroute to Tuktoyaktuk, standby
for weather for helicopter spot sounding ops
Plans: Expect to be in Tuktoyaktuk mid week for Medavac, continue seismic /
bathymetry survey operations in the Beaufort Sea/southern Canada Basin area, Healy is
scheduled to depart from the program Sept 2/3 depending on location.
157
Map: Red lines are the proposed survey lines; highlighted lines are completed to date,
purple dotted line indicates course to Tuktoyaktuk.
158
UNCLOS – CCGS Louis S. St Laurent 2010
Highlights: Two ship operations CCGS Louis S St. Laurent and Coast Guard icebreaker
Healy was suspended for the majority of the week. Most of the week was committed to
traveling to Tuktoyaluk (and return to work area) for a Medavac. Sounding operations did
continue while enroute. To date; 7500 line kilometers of bathymetry has been collected
along with 32 XCTD, 14 XBT, 2 deep-water SVP cast and 61 spot soundings. Helicopter
logged 11.5 hours of flight time. The helicopter spot-sounding ops again were hampered
by weather conditions. Saturday was the last day for helicopter spot soundings
operations.
Weekly Summary: Aug 23 to 29
Aug 30 Monday – sounding ops, fog and lighter ice, enroute Tuktoyaluk, standby for
weather for helicopter spot sounding ops
Aug 31 Tuesday – sounding ops, arrive Tuktoyaluk around 10PM, helicopter to shore for
Medavac, turned north approximately 11 pm after engine work
Sept 1 Wednesday – sounding ops, heading north to start of east to west line, travelling
between Banks Island and ice edge, noticed differences of 100 metres between actual and
charted depths on chart 7600
Sept 2 Thursday – sounding ops, deployed seismic gear at 18:00 local running west with
Healy escort
Sept 3 Friday – sounding and seismic ops, Healy escort, 2 helicopter flights 25 spots
soundings collected
Sept 4 Saturday - sounding and seismic ops, Healy departed for Barrow after lunch,
helicopter spot soundings flight, 13 spot soundings collected, end of helicopter spot
sounding operations, not a requirement in southern areas, stopped to do seismic air gun
calibration after dinner, started logging segy files on Knudsen sounder
Sept 5 Sunday - sounding and seismic ops, Knudsen sounder/computer froze in AM, still
logging depths but no keb/segy files created, rebooted Knudsen computer in science lab
on 3rd level to solve problem
Plans: continue seismic / bathymetry survey operations in the Beaufort Sea/southern
Canada Basin area until required to meet crew change flight scheduled for Sept 15 for
Kugluktuk.
159
Map: Red lines are the proposed survey lines; highlighted lines are sounding/seismic
lines completed to date, a dotted line indicates only sounding operations.
160
UNCLOS – CCGS Louis S. St Laurent 2010
Highlights: Seismic program is finished. To date; 9145 line kilometers of bathymetry has
been collected along with 34 XCTD, 13 XBT, 3 deep-water SVP cast and 61 spot
soundings. Seismic operations ended Saturday, continue sounding ops until Kugluktuk.
Weekly Summary: Sept 6 to Sept 12
Sept 6 Monday - sounding and seismic ops
Sept 7 Tuesday - sounding and seismic ops, problems picking up bottom with the sea
conditions and ship orientation, lost several hours, CHS computer also lost connection
several times to Knudsen sounder during the day
Sept 8 Wednesday - sounding and seismic ops
Sept 9 Thursday - sounding and seismic ops, stopped logging seg-y files, crashes
computer and slows down/corrupts the logging of keb files
Sept 10 Friday - sounding and seismic ops
Sept 11 Saturday - sounding and seismic ops, last day of seismic operations, gear onboard
at noon, deep water SVP cast, continue sounding ops, heading for Paulaltuk for mammal
observers to disembark
Sept 12 Sunday – sounding ops, enroute to Paulatuk
Plans: continue bathymetry operations until Kugluktuk. Board crew change flight to St
John’s on Wednesday Sept 15th and return to Burlington Sept 16th.
Map: Red lines are the survey lines; highlighted lines are sounding/seismic lines
completed to date, a dotted line indicates only sounding operations.
161
162
Appendix B: Bridge Instructions
163
Bridge Instructions, August 6 (JD 218), 2010
1) Proceed to Rendezvous point with USCGC Healy
72º 57.0'N 137º 34.3'W
Distance from Kugluktuk: 560 nMi
(Note: may modify depending on communication with Healy)
2) En Route or upon arrival at rendezvous point, LSSL to conduct deployment and
towing tests of 3.5 kHz system and conduct seismic calibration experiment.
estimated time 6 hours
3) commence survey operations as time permits (waypoints to be provided)
4) Cease survey operations approximately 1300hr August 9 (JD 221)
5) Transfer personnel
6) Approx. 1700hr, August 9 (JD 221), pull seismic gear and proceed to US EEZ
to arrive at 71º 39.174' -148º 11.28' SOL (US EEZ)
for 10:00 hr, August 10 (Day 222)
Deploy seismic equipment and commence survey operations
164
Bridge Instructions, August 10, 2010
1) Proceed to start of line in US EEZ (Waypoint 10 below) (ETA 1030h, Aug. 11
(assuming 12 knots)).
2) Once on station, gear assembly has to be completed and prepared for deployment...that
may take several hours.
3) If US approvals are given, then commence seismics along track provided below. If no
approvals provided, then we wait .
WP
10
11
12
13
14
15
71
72
73
71
74
74
Latitude
39.174
16.296
54.91278
50.24202
19.08114
57.8721
Longitude
-148
11.333
-145
24.594
-145 18.0849
-151 49.41438
-150 17.79852
-158 0.73548
Note that the Healy is to join us at WayPoint 11 to assist with ice breaking. She will be
the lead vessel during seismic operations off the LSSL.
*NOTE: THROUGH MUTUAL AGREEMENT WITH THE HEALY WE ARE
TO RUN AZIMUTHAL TRACKS, NOT GREAT CIRCLE AS PREVIOUS
165
166
Bridge Instructions, August 16, 2010
1) Continuation of seismic operations. At Waypoint 14 (74º 19.08N, 150º 17.79'W)
proceed to Waypoint 16 provided in the table below. Ignore previously provided
Waypoint 15. Continue survey pattern sequentially from 16 through to 20.
WP Latitude
Longitude
16
17
18
19
20
-150° 03.1283'
-154° 41.5019'
-156° 37.1032'
-156° 05.2307'
-146° 30.1164'
74° 43.2317'
75° 42.8441'
75° 51.2512'
76° 09.5383'
76° 35.2378'
Total Track length is 307 nMi
Note: After Waypoint 14, we will be out of the US EEZ and requirements of Marine
Mammal Observations revert back to Canadian guidelines. The US Marine Mammal
Observers are free to transfer back to the Healy at that point in time.
THROUGH MUTUAL AGREEMENT WITH THE HEALY WE ARE TO RUN
AZIMUTHAL TRACKS, NOT GREAT CIRCLE AS PREVIOUS
167
168
Bridge Instructions, August 19, 2010
1) At WayPoint 20, we will bring in the seismic gear and transit to Waypoint 21. We can
break ice for the Healy during that transit, if preferred.
2) Deploy seismic equipment at Waypoint 21 and proceed seismic operations from WP21
to WP22 and WP23
WP Latitude
Longitude
20
21
22
23
-146° 30.12'
-153º 10.00'
-143° 10.00'
-138° 30.00'
76° 35.24'
78° 06.00'
79° 12.00'
78° 53.00'
Total Track length is 321 nMi (including transit from wp20 to wp21)
THROUGH MUTUAL AGREEMENT WITH THE HEALY WE ARE TO RUN
AZIMUTHAL TRACKS, NOT GREAT CIRCLE AS PREVIOUS
169
Bridge Instructions, August 21, 2010
1) At WayPoint 22, we will bring in the seismic gear and transit to Waypoint 24, ignoring
former Waypoint 23. LSSL can break ice for the Healy during transit.
2) waypoint 24 to 25 is meant to pass over the seamount from the SouthWest, where
multibeam data infill is required
3) Deploy seismics - preferably in an open water area near WP 25 and survey up to WP
26
4) Recover seismics and transit/multibeam to WPs 27 and 28
5) Deploy seismics at WP 28 - preferably in open water - and survey to WP 29
6) Recover gear at WP 29
Line/Distance nMi
WP
Latitude
Longitude
Operation
22
79º 12.00'
-143º 10.00'
22-24 / 170 nMi
Transit
24
81º 33.50'
-134º 06.00'
24-25 / 25 nMi
Transit
25
81º 46.34'
-131º 42.60'
25-26 / 200 nMi
Deploy/Survey
26
85º 00.40'
-128º 08.60'
26-27 / 95 nMi
Recover/Transit
27
83º 32.61'
-133º 23.44'
27-28 / 75 nMi
transit
28
82º 31.80'
-139º 10.70'
28-29 / 195 nMi
Deploy/Survey
29
80º 58.71'
-119º 14.18'
Recover
Multibeam data will be collected on transit lines. Seismics will be collected along
Survey lines.
Heavy ice is expected during this survey, particularly on the northern most section
of the line between WP 25 and WP 26, and on the eastern end of the line between
WP 28 and 28. If unable to conduct seismic operations, then we will revert to
bathymetric/multibeam operations.
170
171
Bridge Instructions, August 23, 2010
1) Pull in seismic gear immediately after lunch (aug 23) and transit to WP 23. LSSL can
break ice for the Healy during transit.
2) Dogleg to WP 24 and WP 25 - is meant to pass over the newly discovered seamount
from the SouthWest, where multibeam data infill is required
3) Deploy seismics - WP 25 and survey up to WP 26
4) Recover seismics and transit/multibeam to WPs 27 and 28
5) Deploy seismics at WP 28 - preferably in open water - and survey to WP 29
6) Recover gear at WP 29
Line/Distance nMi
WP
Latitude
Longitude
Operation
22
79º 12.00'
-143º 10.00'
22-23 / 178 nMi
23
81º 24.03'
-134º 46.07
23-24/16 nMi
Transit/mb
24
81º 39.61'
-135º 14.75
24-25 / 32 nMi
Transit/mb
25
81º 46.34'
-131º 42.60'
25-26 / 200 nMi
Deploy/Survey
26
85º 00.40'
-128º 08.60'
26-27 / 95 nMi
Recover/Transit
27
83º 32.61'
-133º 23.44'
27-28 / 75 nMi
transit
28
82º 31.80'
-139º 10.70'
28-29 / 195 nMi
Deploy/Survey
29
80º 58.71'
-119º 14.18'
Transit
Recover
Multibeam data will be collected on transit lines. Seismics will be collected along
Survey lines.
Heavy ice is expected during this survey, particularly on the northern most section
of the line between WP 25 and WP 26, and on the eastern end of the line between
WP 28 and 29. If unable to conduct seismic operations, then we will revert to
bathymetric/multibeam operations.
172
173
Bridge Instructions, August 25, 2010
1) Steam directly to WP 28
2) Deploy seismics at WP 28 and survey to WP 29
3) Recover gear at WP 29
4) Multibeam survey (Louis leading Healy) through from WP 29 through to 36
We're trying to follow a morphologic feature from wp 30 to 36 - Healy will have to offer
instructions based on its multibeam signature.
Longitude
-139º 10.70'
Line/Distance nMi
28
Latitude
82º 31.80'
29
80º 58.71'
-119º 14.18'
194 nMi
Recover
30
80º 44.3005'
124º 18.639'
51 nMi
Multibeam
31
80º 58.5395'
125º 45.6791'
Multibeam
32
80º 47.0839'
126º 35.9663'
Multibeam
33
80º 51.1334'
128º 09.8565'
34
80º 35.644'
128º 52.1972'
Multibeam
35
80º 21.0932'
130º 42.347'
Multibeam
36
80º 14.6493'
-131º 18.1384'
Multibeam
WP
Operation
Deploy/Survey
99 nMi
Multibeam
Heavy ice is expected on the eastern end of the line between WP 28 and 29. If
unable to conduct seismic operations, then we will revert to bathymetric/multibeam
operations.
174
175
Bridge Instructions, August 27, 2010
1) Continue seismics as long as feasible along line between WP 28 and 29. At some
point it will be necessary to recover seismic gear and switch to multibeam mode.
2) Continue in multibeam mode (LSSL leading Healy) through Waypoint 29 and
continue to Waypoint 29A. (29A is 114 nMi from present position; 0930PST, August 27)
3) Multibeam survey (Louis leading Healy) through from WP 29, 29A through to 36
Between WP30 to 36, we are trying to follow a morphologic feature (ridge). Healy will
have to offer instructions based on its multibeam signature.
WP
Line/Distance nMi
28
Latitude
82º 31.80'
Longitude
-139º 10.70'
Operation
29
80º 58.71'
-119º 14.18'
Recover
29A
80º 47.75'
-117º 55.64'
Multibeam (EOL)
30
80º 44.3005'
-124º 18.639'
31
80º 58.5395'
-125º 45.679'
Multibeam
32
80º 47.0839'
-126º 35.966'
Multibeam
33
80º 51.1334'
-128º 09.856'
34
80º 35.644'
-128º 52.197'
Multibeam
35
80º 21.0932'
-130º 42.347'
Multibeam
36
80º 14.6493'
-131º 18.138'
Multibeam
Deploy/Survey
51 nMi
99 nMi
Multibeam
Multibeam
176
177
Bridge Instructions, August 27(2), 2010
1) Healy Multibeam and chirp operations from present position to Waypoint 35.
2) If ice conditions permit, deploy seismics at WP 35 and acquire data to WP35. If no
seismics, then continue with multibeam and chirp.
WP
29
Latitude
80º 58.96'
Longitude
-119º 07.65'
Operation
Distance
Multibeam
29A
80º 47.75'
-117º 55.64'
Multibeam
30
80º 43.64'
-124º 13.99'
Multibeam
31
80º 58.54'
-125º 45.68'
Multibeam
32
80º 42.44'
-126º 06.34'
Multibeam
33
80º 51.13'
-128º 09.86'
Multibeam
34
80º 30.80'
-128º 18.62'
Multibeam
35
80º 30.66'
-129º 54.78'
Multibeam
265 nMi
36
79º 56.36'
-124º 10.47'
Seismic/Multibeam
67 nMi
Possible 2 ship rafting and ceremony here at WP 36
178
Bridge Instructions, Sept 5, 2010
1) Slight course alteration at waypoint 40 to Waypoint 41
on track, deploy Ocean Bottom Seismometer (OBS)
2) Pick up seismics and transit from WP41 to Waypoint 42
3) Deploy seismics and survey to Waypoint 43
2) Survey westward to Waypoint 38 then southward to Waypoint 39. Healy will have to
break off at some point after waypoint 39, but we should be in this finger of lighter ice by
then.
WP
Latitude
Longitude
40
73º 41.1137'
-136º 24.1702'
Line/Distance nMi
Operation
Seismic
41
Deploy OBS
42
70º 59.7718'
-137º 36.1483'
103
43
71º 29.6984'
-131º 29.5989'
344
44
73º 50.8777'
-140º 20.659'
Seismic
179
Bridge Instructions, Sept 5, 2010
1) Slight course alteration at WP40 to WP41
2) Recover seismics at WP41 and transit to WP42
3) Deploy seismics at WP42 and survey to WP43
Line/Distance nMi
WP
Latitude
Longitude
Operation
Seismic
40
73º 41.11'
-136º 24.17'
41
70º 59.77'
-137º 36.15'
162
Seismic
42
71º 29.70'
-131º 29.60'
121
Transit
43
73º 50.88'
-140º 20.66'
213
Seismic
Bridge Instructions, Sept 10, 2010
1) After making WP 43 (ETA 0300h, Sept. 11), turn to port to WP44
180
2) Recover seismics seismics at WP44
3) Conduct Sound Velocity Profile (SVP)
WP
Latitude
Longitude
43
73º 50.88'
73º 42.20'
-140º 20.66'
-142º 28.86'
44
Line/Distance nMi
Operation
Seismic
37
Seismic
SVP
181
Appendix C
Gundalf, G Gun Modeling Results
182
GUNDALF array modelling suite - 1150 in3, 6 m depth Array report
Gundalf revision AIR6.1c, Date 2010-01-07, Epoch 2010-01-07
Sun Sep 05 23:15:03 Atlantic Daylight Time 2010 (David Mosher)
This report is copyright Oakwood Computing Associates Ltd. 2002-. The report is
automatically generated using GUNDALF and it may be freely distributed provided it
retains this copyright notice and is kept as a whole.
Report pre-amble
Author: Mosher
Author Organisation: NRCan
Contents













Signature filtering policy
Some notes on the modelling algorithm
Array summary
Array geometry and gun contribution
Array centres and timing
Array directivity
Signature characteristics
Acoustic energy characteristics
Amplitude drop-out characteristics
Spectral drop-out characteristics
Inventory usage
Physical parameters
Gundalf calibration details
Signature filtering policy
For marine environmental noise reports, Gundalf performs no signature filtering other
than that inherent in modelling at a sample interval small enough to simulate an airgun
array signature at frequencies up to 100kHz.
For all other kinds of reports, Gundalf performs filtering in this order:-
183



If a pre-conditioning filter is chosen, for example, an instrument response, it is
applied at the modelling sample interval.
If the output sample interval is larger than the modelling sample interval, Gundalf
applies appropriate anti-alias filtering. (This can be turned off in the event that
anti-alias filtering is included in the pre-conditioning filter, in which case Gundalf
will issue a warning.)
Finally, Gundalf applies the chosen set of post-filters, Q, Wiener and band-pass
filtering as specified, at the output sample interval.
In reports, when filters are applied, they are applied to the notional sources first so that
signatures, directivity plots and spectra are all filtered consistently.
Finally note that modelled signatures always begin at time zero for reasons of causality.
Anti-alias and pre-condition filtering
In this case, no pre-conditioning filter has been applied.
In this case, no anti-alias filtering was necessary.
Post filtering
Details of the post-filtering used in this report follow. Post filters are applied at the output
sample interval after any pre-conditioning and anti-alias filters have been applied.
Q filtering
No Q filtering performed.
Wiener filtering
No Wiener filtering performed.
Band-pass filtering
Signatures were band-passed filtered using the following parameters:Internally generated as 6.0/18.0 - 128.0/72.0
The amplitude spectrum of the band-pass filter used is shown below.
184
Some notes on the modelling algorithm
The Gundalf airgun modelling engine is the end-product of 15 years of state of the art
research. It takes full account of all air-gun interactions including interactions between
sub-arrays. No assumptions of linear superposition are made. This means that if you
move sub-arrays closer together, the far-field signature will change. The effect is
noticeable even when sub-arrays are separated by as much as 10m.
The engine is capable of modelling airgun clusters right down to the 'super-foam' region
where the bubbles themselves collide and distort. It has been calibrated against both
single and clustered guns for a number of different gun types under laboratory conditions
and accurately predicts peak to peak and primary to bubble parameters across a very wide
range of operating conditions.
In many cases, the predicted signatures are good enough to be used directly in signature
deconvolution procedures.
Array summary
The following table lists the statistics for the array quoted in various commonly used
units for convenience. Note that the rms value is computed over the entire modelled
signature.
185
Array parameter
Array value
Number of guns
3
Total volume (cu.in).
1150.0 ( 18.8 litres)
Peak to peak in bar-m.
11.4 ( 1.14 MPa, 241 db re 1 microPascal. at
1m.)
Zero to peak in bar-m.
6.42 ( 0.642 MPa, 236 db re 1 microPascal. at
1m.)
RMS pressure in bar-m.
0.85 ( 0.085 MPa, 219 db re 1 microPascal. at
1m.)
Primary to bubble (peak to peak)
8.01
Bubble period to first peak (s.)
0.247
Maximum spectral ripple (dB): 10.0 50.0 Hz.
8.39
Maximum spectral value (dB): 10.0 - 50.0
Hz.
197
Average spectral value (dB): 10.0 - 50.0
Hz.
194
Total acoustic energy (Joules)
20505.2
Total acoustic efficiency (%)
8.3
Array geometry and gun contribution
The following table lists all the guns modelled in the array along with their
characteristics. The last column is completed only if the array has actually been modelled
during the interactive session and contains the approximate contribution of that gun as a
percentage of the peak to peak amplitude of the whole array. Please note the following:

The peak to peak varies only as the cube root of the volume for the same gun type
so that even small guns contribute significantly. This is particularly relevant to
drop-out analysis.
The peak to peak can also be depressed due to clustering effects as reported by
Strandenes and Vaage (1992), "Signatures from clustered airguns", First Break,
10(8).
Gun
Pressure
(psi)
Volume
(cuin)
1
1900.0
500.0
2
1900.0
500.0
Type
x
(m.)
y
(m.)
z
(m.)
delay
(s.)
G1.000 0.500 6.000 0.000
GUN
G-
1.000
-
6.000 0.000
sub- p-p contrib
array
(pct.)
1
35.4
1
35.5
186
GUN
3
1900.0
150.0
0.500
G0.000 0.000 6.000 0.000
GUN
1
29.1
The array is shown graphically below.
Hydrophone position: Infinite vertical far-field
<----- Direction of travel ----- --, (1m. grid, plan view)
The red circles denote the maximum radius reached by the bubble. Please note that pressurefield interactions take place over a much larger distance than this, (typically 10 times larger).
However when bubbles touch or overlap, super-foam interaction can be expected. In this zone,
significant peak AND bubble suppression will normally be observed.
Note also that a green rectangle represents a single gun and an orange rectangle indicates that
the gun is currently dropped out. Where present, a yellow rectangle represents a vertical cluster
(V.C.) of guns. Please see the geometry table above for more details. The small number to the
187
above left of each gun is its reference number in this table. For clusters of guns, these reference
numbers mirror the symmetry of the cluster.
Back to top
Array centres and timing
The following diagram shows the array geometric centre, the centre of pressure and the
centre of energy defined as follows:


The array geometric centre is defined to be the centre of the rectangle formed by
the largest and smallest x and y values of the active guns (dropped out guns are
ignored). This is shown as a blue circle.
The centre of pressure is defined to be the array centre when each active gun
position is weighted by its contribution to the overall peak to peak pressure value.
This is shown as a red circle.
The centre of energy is computed by weighting the coordinates by the self-energy
of the active gun at that position. In an interacting array this may be a long way
from the centre of pressure as some guns may absorb energy giving a negative
self-energy. This is shown as a black circle.
Depending on how first breaks are calculated, these can be used for first break analysis.
Dropped out guns are shown as orange rectangles whilst live guns are shown as green
rectangles.
Array centres
188
The geometric centre is at ( 0.5, 0, 6)
The centre of pressure is at ( 0.709,-0.00025, 6)
The centre of energy is at ( -0.224,-0.00475, 6)
Note that Gundalf by default uses the deepest gun to define time zero for the vertical farfield and it uses the nearest gun to the observation point to define time zero if an
observation point is specified. This means that if one gun is accidentally run deep, this
will cause the bulk of the signature to appear to be delayed. It is still a research question
how an airgun array should be timed. There are several candidates as defined above but it
is not currently clear which if any is appropriate in complex scenarios such as Ocean
Bottom Deployment.
Back to top
189
Array directivity
The following tables show the inline and crossline directivity of the array in both (anglefrequency) and (angle-amplitude) form and optionally, the azimuthal directivity (thetaphi) form.
Note that the effects of cable ghosting if present are not shown in Gundalf directivity
displays although source ghosting is included. This matches common practice in such
displays.
For inline directivity displays, the x-axis is the inline angle from the vertical with the
word fore indicating the end nearest the boat. For crossline directivity displays, the x-axis
is the crossline angle from the vertical with the word port indicating the port side.
Note that inline is used nominally to mean any angle within 45 degrees of the boat
direction (which corresponds to a bearing of zero degrees). Similarly, crossline is used
nominally to mean any angle within 45 degrees of the perpendicular to the boat direction
which is measured as a bearing of 90 degrees, (i.e. starboard). The nominal inline and
crossline angles can be set by the user in the report options. The values used are indicated
in the diagram titles below as bearings.
Where shown, the azimuthal plots show contours at four chosen frequencies as a function
of phi (angle from the x-axis, opposite to the boat direction) and theta (the angle from the
vertical). A bearing of zero degrees corresponds to a value of phi of 180 degrees.
Angle-frequency form
The following tables show the inline and crossline directivity of the array in (dip anglefrequency) form. Both plots are scaled as dB. relative to 1 microPa. per Hz. at 1m.
Inline directivity, bearing = 0 degrees
190
Crossline directivity, bearing = 90 degrees
191
Angle-amplitude form
The following tables show the inline and crossline directivity of the array in (dip angle,
amplitude) form. The computed signature (or under option the amplitude spectrum) for
each angle is shown in colour varying form with red signatures shown in the centre,
shading to blue at the furthest angles computed. The vertical scale indicates the type of
plot, time or frequency. Both types of plot are individually scaled and plotted with the
same units as the corresponding plots in the Signature Characteristics section.
Inline directivity, bearing = 0 degrees
Crossline directivity, bearing = 90 degrees
192
Back to top
Signature characteristics
The following tables show the signature parameters, the signature and the amplitude
spectrum of the modelled signature.
The amplitude spectrum is shown in units of dB. relative to 1 microPa. per Hz. at 1m.
The position of the bubble by default is determined internally but can be overridden by
interacting with the modelled signature using the right hand mouse button to determine
the start of the bubble.
Signature ghost information
The source ghost has been included. The source ghost was input directly with the value 0.7.
The cable ghost has been switched off.
Output signature parameters
Signature filtering
details
Number of samples in
signature
Sample interval
(s.)
Hydrophone
position
193
6.0/18.0 - 128.0/72.0
2000
0.00025
Infinite vertical farfield
Signature and statistics
In this case, the bubble position was determined internally. The start of the search
window for the bubble was: 0.04 (s.)
Peak to peak in Zero to peak in Primary to bubble (peak Bubble period to first
bar-m.
bar-m.
to peak)
peak (s.)
11.4
6.42
8.01
0.24675
Band-pass filter: 6.0/18.0 - 128.0/72.0
Filtered amplitude spectrum
Amplitude spectrum. Amplitude Units are dB. relative to 1 mPa / Hz. at 1m.
194
Close up of amplitude spectrum
Back to top
195
Acoustic energy characteristics
The following table lists the individual gun contributions to the acoustic energy field in
joules. A negative value means the gun is actually absorbing energy. This is very
common in interacting arrays. It does not however mean that the gun is damaging the
array performance. Rather it is acting as a catalyst to allow the other guns to perform
more efficiently. The total acoustic energy gives the true performance of the array as a
whole. See Laws, Parkes and Hatton (1988) Energy-interaction: The long-range
interaction of seismic sources, Geophysical Prospecting (36), p333-348 and 38(1) 1990
p.104 for more details. Note that internal energy is not included in the data below. The
true acoustic efficiency of airgun arrays is typically < 5% of the total initial energy.
Overall acoustic energy contribution
Total acoustic
Acoustic energy
energy output output due to energy(j.)
interaction (j.)
20505.2
Total potential
energy available
in array(j.)
Percentage of total
potential energy
appearing as acoustic
energy
247102.5
8.3%
6476.0
Individual acoustic energy contributions
Volume (cuin) x (m.) y (m.) z (m.)
Acoustic energy contribution (j.)
500.0
1.00
0.50
6.00
-2397.6
500.0
1.00
-0.50
6.00
-2203.0
150.0
0.00
0.00
6.00
25105.8
The red entries denote guns which are catalysing the array by absorbing energy.
Back to top
Amplitude drop-out characteristics
The following table lists those 1 and 2 gun combinations which would cause the drop-out
percentage limit for amplitudes to be breached. If the drop-out limit is set to 0.0 or if the
far-field signature parameters have not been calculated, this analysis is not done. (Note
that this calculation is by its very nature, approximate as it is calculated from the notional
sources. In order to do drop-out calculation correctly, each combination of 1, 2 and
potentially more guns must be physically dropped out and the array recalculated because
the overall interaction balance changes. Gundalf can do this under option for various gun
drop-outs but the calculation can be very expensive. The simple amplitude drop-out
calculation described in this section is a first approximation.)
The maximum allowable percentage drop in peak to peak amplitude was set to 10.0
196
Single gun percentage amplitude drop breaches
Drop-out detail
Approximate percent amplitude loss
GUN 1; G-GUN: Vol 500.00
35.4
GUN 2; G-GUN: Vol 500.00
35.5
GUN 3; G-GUN: Vol 150.00
29.1
Double gun percentage amplitude drop breaches
Drop-out detail
Approximate percent amplitude
loss
GUN 1; G-GUN: Vol 500.00 and GUN 2; G-GUN:
Vol 500.00
70.9
GUN 1; G-GUN: Vol 500.00 and GUN 3; G-GUN:
Vol 150.00
64.5
GUN 2; G-GUN: Vol 500.00 and GUN 3; G-GUN:
Vol 150.00
64.6
Back to top
Spectral drop-out characteristics
Information only available in Gundalf Optimiser
Back to top
Physical parameters
The following table summarises the physical parameters used in modelling.
Sea
temperature
(C)
-1
Velocity of sound in
Expected dominant
Observed wave
water (m./s.)
frequency in signature (Hz)
height (m)
1444
20.0
0.0
Note that the gun controller variation was set to 0.0 (s.)
197
GUNDALF array modelling suite – 1150 in3, 12 m depth Array report
Gundalf revision AIR6.1c, Date 2010-01-07, Epoch 2010-01-07
Sun Sep 05 23:17:10 Atlantic Daylight Time 2010 (David Mosher)
This report is copyright Oakwood Computing Associates Ltd. 2002-. The report is
automatically generated using GUNDALF and it may be freely distributed provided it
retains this copyright notice and is kept as a whole.
Report pre-amble
Author: Mosher
Author Organisation: NRCan
Contents













Signature filtering policy
Some notes on the modelling algorithm
Array summary
Array geometry and gun contribution
Array centres and timing
Array directivity
Signature characteristics
Acoustic energy characteristics
Amplitude drop-out characteristics
Spectral drop-out characteristics
Inventory usage
Physical parameters
Gundalf calibration details
Signature filtering policy
For marine environmental noise reports, Gundalf performs no signature filtering other
than that inherent in modelling at a sample interval small enough to simulate an airgun
array signature at frequencies up to 100kHz.
198
For all other kinds of reports, Gundalf performs filtering in this order:


If a pre-conditioning filter is chosen, for example, an instrument response, it is
applied at the modelling sample interval.
If the output sample interval is larger than the modelling sample interval, Gundalf
applies appropriate anti-alias filtering. (This can be turned off in the event that
anti-alias filtering is included in the pre-conditioning filter, in which case Gundalf
will issue a warning.)
Finally, Gundalf applies the chosen set of post-filters, Q, Wiener and band-pass
filtering as specified, at the output sample interval.
In reports, when filters are applied, they are applied to the notional sources first so that
signatures, directivity plots and spectra are all filtered consistently.
Finally note that modelled signatures always begin at time zero for reasons of causality.
Anti-alias and pre-condition filtering
In this case, no pre-conditioning filter has been applied.
In this case, no anti-alias filtering was necessary.
Post filtering
Details of the post-filtering used in this report follow. Post filters are applied at the output
sample interval after any pre-conditioning and anti-alias filters have been applied.
Q filtering
No Q filtering performed.
Wiener filtering
No Wiener filtering performed.
Band-pass filtering
Signatures were band-passed filtered using the following parameters:Internally generated as 6.0/18.0 - 128.0/72.0
The amplitude spectrum of the band-pass filter used is shown below.
199
Some notes on the modelling algorithm
The Gundalf airgun modelling engine is the end-product of 15 years of state of the art
research. It takes full account of all air-gun interactions including interactions between
sub-arrays. No assumptions of linear superposition are made. This means that if you
move sub-arrays closer together, the far-field signature will change. The effect is
noticeable even when sub-arrays are separated by as much as 10m.
The engine is capable of modelling airgun clusters right down to the 'super-foam' region
where the bubbles themselves collide and distort. It has been calibrated against both
single and clustered guns for a number of different gun types under laboratory conditions
and accurately predicts peak to peak and primary to bubble parameters across a very wide
range of operating conditions.
In many cases, the predicted signatures are good enough to be used directly in signature
deconvolution procedures.
Array summary
The following table lists the statistics for the array quoted in various commonly used
units for convenience. Note that the rms value is computed over the entire modelled
signature.
200
Array parameter
Array value
Number of guns
3
Total volume (cu.in).
1150.0 ( 18.8 litres)
Peak to peak in bar-m.
12.9 ( 1.29 MPa, 242 db re 1 microPascal. at
1m.)
Zero to peak in bar-m.
6.33 ( 0.633 MPa, 236 db re 1 microPascal. at
1m.)
RMS pressure in bar-m.
1.08 ( 0.108 MPa, 221 db re 1 microPascal. at
1m.)
Primary to bubble (peak to peak)
4.62
Bubble period to first peak (s.)
0.052
Maximum spectral ripple (dB): 10.0 50.0 Hz.
12.2
Maximum spectral value (dB): 10.0 - 50.0
Hz.
202
Average spectral value (dB): 10.0 - 50.0
Hz.
196
Total acoustic energy (Joules)
29209.8
Total acoustic efficiency (%)
11.8
Array geometry and gun contribution
The following table lists all the guns modelled in the array along with their
characteristics. The last column is completed only if the array has actually been modelled
during the interactive session and contains the approximate contribution of that gun as a
percentage of the peak to peak amplitude of the whole array. Please note the following:

The peak to peak varies only as the cube root of the volume for the same gun type
so that even small guns contribute significantly. This is particularly relevant to
drop-out analysis.
The peak to peak can also be depressed due to clustering effects as reported by
Strandenes and Vaage (1992), "Signatures from clustered airguns", First Break,
10(8).
Gun
Pressure
(psi)
Volume
(cuin)
1
1900.0
500.0
2
1900.0
500.0
Type
x
(m.)
y
delay
z (m.)
(m.)
(s.)
G1.000 0.500 12.000 0.000
GUN
G-
1.000
-
12.000 0.000
sub- p-p contrib
array
(pct.)
1
37.1
1
37.1
201
GUN
3
1900.0
150.0
0.500
G0.000 0.000 12.000 0.000
GUN
1
25.8
The array is shown graphically below.
Hydrophone position: Infinite vertical far-field
<----- Direction of travel ----- --, (1m. grid, plan view)
The red circles denote the maximum radius reached by the bubble. Please note that pressurefield interactions take place over a much larger distance than this, (typically 10 times larger).
However when bubbles touch or overlap, super-foam interaction can be expected. In this zone,
significant peak AND bubble suppression will normally be observed.
Note also that a green rectangle represents a single gun and an orange rectangle indicates that
the gun is currently dropped out. Where present, a yellow rectangle represents a vertical cluster
(V.C.) of guns. Please see the geometry table above for more details. The small number to the
202
above left of each gun is its reference number in this table. For clusters of guns, these reference
numbers mirror the symmetry of the cluster.
Back to top
Array centres and timing
The following diagram shows the array geometric centre, the centre of pressure and the
centre of energy defined as follows:


The array geometric centre is defined to be the centre of the rectangle formed by
the largest and smallest x and y values of the active guns (dropped out guns are
ignored). This is shown as a blue circle.
The centre of pressure is defined to be the array centre when each active gun
position is weighted by its contribution to the overall peak to peak pressure value.
This is shown as a red circle.
The centre of energy is computed by weighting the coordinates by the self-energy
of the active gun at that position. In an interacting array this may be a long way
from the centre of pressure as some guns may absorb energy giving a negative
self-energy. This is shown as a black circle.
Depending on how first breaks are calculated, these can be used for first break analysis.
Dropped out guns are shown as orange rectangles whilst live guns are shown as green
rectangles.
Array centres
203
The geometric centre is at ( 0.5, 0, 12)
The centre of pressure is at ( 0.742,-0.000197, 12)
The centre of energy is at ( 0.121,-0.00362, 12)
Note that Gundalf by default uses the deepest gun to define time zero for the vertical farfield and it uses the nearest gun to the observation point to define time zero if an
observation point is specified. This means that if one gun is accidentally run deep, this
will cause the bulk of the signature to appear to be delayed. It is still a research question
how an airgun array should be timed. There are several candidates as defined above but it
is not currently clear which if any is appropriate in complex scenarios such as Ocean
Bottom Deployment.
Back to top
204
Array directivity
The following tables show the inline and crossline directivity of the array in both (anglefrequency) and (angle-amplitude) form and optionally, the azimuthal directivity (thetaphi) form.
Note that the effects of cable ghosting if present are not shown in Gundalf directivity
displays although source ghosting is included. This matches common practice in such
displays.
For inline directivity displays, the x-axis is the inline angle from the vertical with the
word fore indicating the end nearest the boat. For crossline directivity displays, the x-axis
is the crossline angle from the vertical with the word port indicating the port side.
Note that inline is used nominally to mean any angle within 45 degrees of the boat
direction (which corresponds to a bearing of zero degrees). Similarly, crossline is used
nominally to mean any angle within 45 degrees of the perpendicular to the boat direction
which is measured as a bearing of 90 degrees, (i.e. starboard). The nominal inline and
crossline angles can be set by the user in the report options. The values used are indicated
in the diagram titles below as bearings.
Where shown, the azimuthal plots show contours at four chosen frequencies as a function
of phi (angle from the x-axis, opposite to the boat direction) and theta (the angle from the
vertical). A bearing of zero degrees corresponds to a value of phi of 180 degrees.
Angle-frequency form
The following tables show the inline and crossline directivity of the array in (dip anglefrequency) form. Both plots are scaled as dB. relative to 1 microPa. per Hz. at 1m.
Inline directivity, bearing = 0 degrees
205
Crossline directivity, bearing = 90 degrees
206
Angle-amplitude form
The following tables show the inline and crossline directivity of the array in (dip angle,
amplitude) form. The computed signature (or under option the amplitude spectrum) for
each angle is shown in colour varying form with red signatures shown in the centre,
shading to blue at the furthest angles computed. The vertical scale indicates the type of
plot, time or frequency. Both types of plot are individually scaled and plotted with the
same units as the corresponding plots in the Signature Characteristics section.
Inline directivity, bearing = 0 degrees
Crossline directivity, bearing = 90 degrees
207
Back to top
Signature characteristics
The following tables show the signature parameters, the signature and the amplitude
spectrum of the modelled signature.
The amplitude spectrum is shown in units of dB. relative to 1 microPa. per Hz. at 1m.
The position of the bubble by default is determined internally but can be overridden by
interacting with the modelled signature using the right hand mouse button to determine
the start of the bubble.
Signature ghost information
The source ghost has been included. The source ghost was input directly with the value 0.7.
The cable ghost has been switched off.
Output signature parameters
Signature filtering
details
Number of samples in
signature
Sample interval
(s.)
Hydrophone
position
208
6.0/18.0 - 128.0/72.0
2000
0.00025
Infinite vertical farfield
Signature and statistics
In this case, the bubble position was determined internally. The start of the search
window for the bubble was: 0.04 (s.)
Peak to peak in Zero to peak in Primary to bubble (peak Bubble period to first
bar-m.
bar-m.
to peak)
peak (s.)
12.9
6.33
4.62
0.052
Band-pass filter: 6.0/18.0 - 128.0/72.0
Filtered amplitude spectrum
Amplitude spectrum. Amplitude Units are dB. relative to 1 mPa / Hz. at 1m.
209
Close up of amplitude spectrum
Back to top
210
Acoustic energy characteristics
The following table lists the individual gun contributions to the acoustic energy field in
joules. A negative value means the gun is actually absorbing energy. This is very
common in interacting arrays. It does not however mean that the gun is damaging the
array performance. Rather it is acting as a catalyst to allow the other guns to perform
more efficiently. The total acoustic energy gives the true performance of the array as a
whole. See Laws, Parkes and Hatton (1988) Energy-interaction: The long-range
interaction of seismic sources, Geophysical Prospecting (36), p333-348 and 38(1) 1990
p.104 for more details. Note that internal energy is not included in the data below. The
true acoustic efficiency of airgun arrays is typically < 5% of the total initial energy.
Overall acoustic energy contribution
Total acoustic
Acoustic energy
energy output output due to energy(j.)
interaction (j.)
29209.8
Total potential
energy available
in array(j.)
Percentage of total
potential energy
appearing as acoustic
energy
247102.5
11.8%
10150.2
Individual acoustic energy contributions
Volume (cuin) x (m.) y (m.) z (m.) Acoustic energy contribution (j.)
500.0
1.00
0.50 12.00
1660.1
500.0
1.00 -0.50 12.00
1871.5
150.0
0.00
25678.1
0.00 12.00
Back to top
Amplitude drop-out characteristics
The following table lists those 1 and 2 gun combinations which would cause the drop-out
percentage limit for amplitudes to be breached. If the drop-out limit is set to 0.0 or if the
far-field signature parameters have not been calculated, this analysis is not done. (Note
that this calculation is by its very nature, approximate as it is calculated from the notional
sources. In order to do drop-out calculation correctly, each combination of 1, 2 and
potentially more guns must be physically dropped out and the array recalculated because
the overall interaction balance changes. Gundalf can do this under option for various gun
drop-outs but the calculation can be very expensive. The simple amplitude drop-out
calculation described in this section is a first approximation.)
The maximum allowable percentage drop in peak to peak amplitude was set to 10.0
Single gun percentage amplitude drop breaches
Drop-out detail
Approximate percent amplitude loss
211
GUN 1; G-GUN: Vol 500.00
37.1
GUN 2; G-GUN: Vol 500.00
37.1
GUN 3; G-GUN: Vol 150.00
25.8
Double gun percentage amplitude drop breaches
Drop-out detail
Approximate percent amplitude
loss
GUN 1; G-GUN: Vol 500.00 and GUN 2; G-GUN:
Vol 500.00
74.2
GUN 1; G-GUN: Vol 500.00 and GUN 3; G-GUN:
Vol 150.00
62.9
GUN 2; G-GUN: Vol 500.00 and GUN 3; G-GUN:
Vol 150.00
62.9
Back to top
Spectral drop-out characteristics
Information only available in Gundalf Optimiser
Back to top
Physical parameters
The following table summarises the physical parameters used in modelling.
Sea
temperature
(C)
-1
Expected dominant
Observed wave
Velocity of sound in
water (m./s.)
frequency in signature (Hz)
height (m)
1444
20.0
0.0
Note that the gun controller variation was set to 0.0 (s.)
Back to top
Gundalf calibration details
All modelling software requires calibration against convincing experimental data.
Gundalf provides accurate modelling of airguns across a wide range of gun types, gun
parameters and operating environments, however, we do not expect you to take this
212
simply on trust. It is therefore our policy to keep users of Gundalf aware of its latest
calibration status and up to date information is available under Help -> Calibration.
213
Appendix D
Daily Gravity Plots
214
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/07 (day 219) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
219.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
219.25
219.50
219.75
220.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
219.00
-20
219.25
219.50
Day of 2010
2010 Aug 18 13:22:21
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day219.ps
219.75
-30
220.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/08 (day 220) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
220.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
220.25
220.50
220.75
221.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
220.00
-20
220.25
220.50
Day of 2010
2010 Aug 18 13:22:23
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day220.ps
220.75
-30
221.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/09 (day 221) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
221.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
221.25
221.50
221.75
222.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
221.00
-20
221.25
221.50
Day of 2010
2010 Aug 18 13:22:24
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day221.ps
221.75
-30
222.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/10 (day 222) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
222.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
222.25
222.50
222.75
223.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
222.00
-20
222.25
222.50
Day of 2010
2010 Aug 18 13:22:25
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day222.ps
222.75
-30
223.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/11 (day 223) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
223.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
223.25
223.50
223.75
224.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
223.00
-20
223.25
223.50
Day of 2010
2010 Aug 18 13:22:26
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day223.ps
223.75
-30
224.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/12 (day 224) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
224.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
224.25
224.50
224.75
225.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
224.00
-20
224.25
224.50
Day of 2010
2010 Aug 18 13:22:28
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day224.ps
224.75
-30
225.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/13 (day 225) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
225.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
3000
Depth (m)
Day of 2010
3500
225.25
225.50
225.75
226.00
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
225.00
-20
225.25
225.50
Day of 2010
2010 Aug 20 11:38:53
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day225.ps
225.75
-30
226.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
Echsounder (1min avg)
IBCAO grid (1arc-min)
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/14 (day 226) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
226.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
3000
Depth (m)
Day of 2010
3500
226.25
226.50
226.75
227.00
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
226.00
-20
226.25
226.50
Day of 2010
2010 Aug 20 11:38:54
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day226.ps
226.75
-30
227.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
Echsounder (1min avg)
IBCAO grid (1arc-min)
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/15 (day 227) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
227.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
3000
Depth (m)
Day of 2010
3500
227.25
227.50
227.75
228.00
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
227.00
-20
227.25
227.50
Day of 2010
2010 Aug 20 11:38:56
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day227.ps
227.75
-30
228.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
Echsounder (1min avg)
IBCAO grid (1arc-min)
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/16 (day 228) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
228.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
3000
Depth (m)
Day of 2010
3500
228.25
228.50
228.75
229.00
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
228.00
-20
228.25
228.50
Day of 2010
2010 Aug 20 11:38:57
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day228.ps
228.75
-30
229.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
Echsounder (1min avg)
IBCAO grid (1arc-min)
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/17 (day 229) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
229.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
3000
Depth (m)
Day of 2010
3500
229.25
229.50
229.75
230.00
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
229.00
-20
229.25
229.50
Day of 2010
2010 Aug 20 11:38:59
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day229.ps
229.75
-30
230.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
Echsounder (1min avg)
IBCAO grid (1arc-min)
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/18 (day 230) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
230.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
3000
Depth (m)
Day of 2010
3500
230.25
230.50
230.75
231.00
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
230.00
-20
230.25
230.50
Day of 2010
2010 Aug 20 11:39:00
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day230.ps
230.75
-30
231.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
Echsounder (1min avg)
IBCAO grid (1arc-min)
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/19 (day 231) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
231.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
231.25
231.50
231.75
232.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
231.00
-20
231.25
231.50
Day of 2010
2010 Aug 20 11:39:02
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day231.ps
231.75
-30
232.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/20 (day 232) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
232.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
232.25
232.50
232.75
233.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
232.00
-20
232.25
232.50
Day of 2010
2010 Aug 27 09:59:55
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day232.ps
232.75
-30
233.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/21 (day 233) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
233.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
233.25
233.50
233.75
234.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
233.00
-20
233.25
233.50
Day of 2010
2010 Aug 27 09:59:57
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day233.ps
233.75
-30
234.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/22 (day 234) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
234.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
234.25
234.50
234.75
235.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
234.00
-20
234.25
234.50
Day of 2010
2010 Aug 27 09:59:59
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day234.ps
234.75
-30
235.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/23 (day 235) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
235.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
235.25
235.50
235.75
236.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
235.00
-20
235.25
235.50
Day of 2010
2010 Sep 02 08:51:01
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day235.ps
235.75
-30
236.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/24 (day 236) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
236.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
236.25
236.50
236.75
237.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
236.00
-20
236.25
236.50
Day of 2010
2010 Sep 02 08:51:04
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day236.ps
236.75
-30
237.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/25 (day 237) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
237.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
237.25
237.50
237.75
238.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
237.00
-20
237.25
237.50
Day of 2010
2010 Sep 02 08:51:06
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day237.ps
237.75
-30
238.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/26 (day 238) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
238.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
238.25
238.50
238.75
239.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
238.00
-20
238.25
238.50
Day of 2010
2010 Sep 02 08:51:09
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day238.ps
238.75
-30
239.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/27 (day 239) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
239.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
239.25
239.50
239.75
240.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
239.00
-20
239.25
239.50
Day of 2010
2010 Sep 02 08:51:12
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day239.ps
239.75
-30
240.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/28 (day 240) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
240.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
240.25
240.50
240.75
241.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
240.00
-20
240.25
240.50
Day of 2010
2010 Sep 02 08:52:45
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day240.ps
240.75
-30
241.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/29 (day 241) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
241.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
241.25
241.50
241.75
242.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
241.00
-20
241.25
241.50
Day of 2010
2010 Sep 02 08:52:47
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day241.ps
241.75
-30
242.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/30 (day 242) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
242.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
242.25
242.50
242.75
243.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
242.00
-20
242.25
242.50
Day of 2010
2010 Sep 02 08:52:50
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day242.ps
242.75
-30
243.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
LSSL2010 Gravity/Bathymetry/GPS -- 2010/08/31 (day 243) -- filter=gaussian_sd2min
Free-air gravity anomaly (mGal)
Day of 2010
243.00
100
80
60
40
20
0
-20
-40
bgm223
ArcGP_v2 grid
-60
-80
-100
0
243.25
243.50
243.75
244.00
500
Depth (m)
1000
1500
2000
2500
3000
Echsounder (1min avg)
IBCAO grid (1arc-min)
4000
360
30
15
300
20
240
10
180
0
12
9
6
3
0
120
60
-10
Eotvos Corr.
Speed
Course
0
243.00
-20
243.25
243.50
Day of 2010
2010 Sep 02 08:54:52
QC_grav.LSSL2010.merge.gaussian_sd2min.1min.day243.ps
243.75
-30
244.00
Eotvos Correction (mGal)
18
Course (deg)
Speed (kts)
3500
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