View report for CCGS Hudson HUD13004 Leg1

View report for CCGS Hudson HUD13004 Leg1
CCGS HUDSON SPRING CRUISE 2013, HUD 2013-004
REPORT ON THE RECOVERY AND DEPLOYMENT OF
RAPID-WAVE MOORINGS IN THE SCOTIAN SLOPE-RISE
4 APRIL-12 APRIL 2013
MIGUEL ÁNGEL MORALES MAQUEDA AND JEFFREY PUGH
NATIONAL OCEANOGRAPHY CENTRE
Table of Contents
INTRODUCTION................................................................................................................................3
NARRATIVE.......................................................................................................................................3
RS ARRAY RECOVERY....................................................................................................................5
Notes on recovered instruments.......................................................................................................8
1. Bottom pressure recorders......................................................................................................8
2. RDI Workhorse ADCPs........................................................................................................10
3. SBE37 Microcats..................................................................................................................12
4. CTD data...............................................................................................................................12
RS LINE ARRAY REDEPLOYMENT.............................................................................................13
Preparation of BPRs for deployment............................................................................................13
Preparation of microCATs for deployment (calibration dips).......................................................15
APPENDIX. MOORING DIAGRAMS ............................................................................................21
Deployments 2011.........................................................................................................................21
Deployments 2013.........................................................................................................................28
2
INTRODUCTION
This is the first leg of the annual CCGS Hudson Spring cruise, which combines work for the
Canadian AZMP (Atlantic Zone Monitoring Program) and the UK funded Western Atlantic
Variability Experiment (WAVE), a component of the UK Natural Environment Research Council's
RAPID-WATCH1 Program. The objectives of this cruise are, first, to recover 7 moorings deployed
in September 2011 (see cruise report HUD2011043) and, second, to deploy a set of 6 replacement
moorings for a period of 18 months (April 2013-September 2014). The moorings record bottom
pressure, currents, temperature, and conductivity (from which salinity is calculated) at various
depths. The scientific purpose of these moorings is to measure bottom pressure changes in the
western Atlantic and, from these changes, infer the variability of the Atlantic meridional
overturning circulation, which, to leading order, is governed by pressure variability on the western
ocean boundary.
In RAPID-WAVE missions prior to 2011, moorings were deployed for one year only. HUD201143
was the first time that the mooring line was deployed for 18 months. Successful recovery of these
moorings in the present cruise will indicate that 1 ½-year deployments can be done without
compromising the safety of the equipment. Being able to deploy the array for longer periods of time
will significantly reduce the costs of maintaining the line.
NARRATIVE
Wednesday 03-04-2013. Jeff Pugh and I arrived in BIO at ~0900 local time (ADT, or Atlantic
Daylight Time, which is 3 hours behind GMT). We spent the morning and part of the afternoon
testing and readying 6 Bottom Pressure Recorders for deployment. The BPRs were programmed to
record for a period of ~24 hr in conjunction with a high-accuracy barometer. These data will allow
us to accurately determine the pressure offset of each BPR. I had a discussion with John Loder and
Dave Hebert (PSO) at ~0300 about the location of the moorings sites. There will be an attempt at
dragging for the moorings lost at RS5 (2nd deployment, 2009) and RS6 (3th deployment, 2010)
during the AZMP 2013 Fall cruise on the Hudson. It is therefore imperative that the new moorings
deployed at RS5 and RS6 during the Spring cruise are sufficiently separated from the lost moorings
to minimize the risk of accidentally hitting the wrong mooring during the dragging operations in the
fall.
Thursday 04-04-2013. Jeff Pugh and I embarked on the Hudson at ~0830 ADT. The ship left the
quay at ~1030 ADT. Departure was initially planned for 0900 ADT but a number of problems with
the lifeboats (new parts for the launching mechanism of the boats had to be ordered and installed, as
some of the old ones had been found faulty during routine ship tests two days earlier). This is the
first cruise of the year for the Hudson. Quite a few members of the crew and officers are new to the
ship and also to mooring work. It will take some time for them to familiarise themselves with the
mooring techniques involved. Fortunately, the BIO technician in charge of mooring operations, Jay
Barthelotte, has many years of experience in the field and has been involved with the RAPIDWAVE project since 2008. The ship will be on ADT for the duration of the cruise. After departure,
we headed for the Bedford Basin to run a series of tests on the ship and on some of the scientific
equipment before leaving for the Scotian Shelf and Slope. The weather forecast for the East Scotian
Slope is for wind to pick up through Friday, with strong southerlies (40 kn) but easing toward
Sunday and Monday. A boat drill was carried out in the basin at ~1100. All tests were completed at
~1440 ADT, at which time the Hudson left the Bedford Basin. Ship familiarisation for scientific
1 WATCH stands for “Will the Atlantic Thermohaline Circulation Halt?”
3
personnel took place from ~1600 ADT to ~1700 ADT. From 1815 ADT to 2030 ADT, Jeff and I
downloaded the data from the 24 hour BPR and barometer tests that we had started on Wednesday.
The BPRs were then reset to start logging on 04-04-2013 at 2355 GMT ready for deployment.
Friday 05-04-2013. We have been recovering moorings in succession since about 1000 ADT. The
moorings at RS1 to RS5 have been recovered without problems. The plan is to recover the two
remaining moorings at RS6 on Saturday 06-04-2013. The weather is expected to deteriorate in the
evening of Friday but them progressively improve throughout Saturday.
Saturday 06-04-2013. Bad weather. Westerly winds (35 kn) and waves 4-6 m high. The plan is to
sit at RS6 while the gale passes and, in the mean time, do the calibration dips for new and old
instruments. A calibration dip was started at ~0930 ADT at or near station HL9 (close to RS6). All
available 3500 m rated microCATs were calibrated there. The cast ended at ~1400 ADT. The ship
then proceeded to the HL11 site to carry out a second calibration dip for all the 7000 m rated
microCATs that are available (i.e., all except those still deployed at RS6). At around 1630 ADT,
half way to HL11, it was decided to turn around and head for CTD station HL8 instead. The reason
for this change was that it was realised that the gale would have not weakened sufficiently upon our
arrival in HL11 to permit a safe deployment of the CTD rosette. The ETA at HL8 was midnight of
Saturday. According to the weather forecast, the worst of the gale should have passed by this time.
Sunday 07-04-2013. An AZMP CTD cast took pace at HL8. This included dipping the remaining
RAPID microCATs for calibration. The only microCATs left that need calibration are those still
deployed at RS6. The plan for today is to recover RS6 and start re-deploying as many moorings as
possible starting at RS6 and working our way up the RS Line. The Canadian Weather Office
forecast for today is: “wind northwest 25 knots diminishing to north 10 to 15 this morning and to
light this afternoon. Wind increasing to southwest 10 to 15 Monday morning and to southwest 15 to
20 Monday afternoon”. Waves diminishing 3-4 m to 1 m near midnight. The long mooring at RS6
was recovered in the morning, followed by the short mooring containing only a SBE53. The new
mooring at RS6 was deployed by about 0430 ADT very close to the position of the RS6 mooring of
2011, as agreed in our discussion with John Loder and Dave Hebert on 03-04-2013.
Monday 08-04-2013. CTD casts at HL9 and HL7 were done over night. At HL7, the remaining
microCATs from the RAPID moorings were dipped for calibration. The expectation was that we
might be able to deploy at least four moorings, perhaps all five, today. In practice, only three
moorings were deployed, namely, RS5, RS4 and RS3. An informal bathymetric survey was carried
out around the target deployment position at RS5 to make sure that the sea floor in the deployment
area is not too rugged. The chosen deployment site was located about a mile south eastwards of the
location initially considered in the meeting with Loder and Dave Hebert on 03-04-2013. This
position is about 2.5 miles to the east of our best position for the RS5 lost mooring. Although the
mooring at RS4 was deployed very close to the position used in 2011, there was a discrepancy in
the M-Cal-derived depths for the “old” mooring (~2780 m) and the “new” mooring (~2730 m). Part
of the discrepancy is explained by the fact that the speed of sound used is not quite the same (1500
m/s in 2011 vs 1489 m/s in the present cruise), but the largest part of the disparity remains
unexplained.
Tuesday 09-04-2013. Deployments at RS1 and RS2 took place in the morning. Poor visibility
because of fog but otherwise fair weather conditions. Jeff and I run a test on SBE53-45 as per
instructions from Gary Morast, from SBE, to verify the integrity of the reference crystal. The test
consisted on typing the command “tsx” and record the instrument output. The instrument produces
a line of “esoteric” data every two minutes. Fourteen of these lines were sent to Gary via e-mail for
inspection. The RAPID component of the cruise has come to an end.
RS ARRAY RECOVERY
The moorings at RS1 to RS5 were recovered without incidents on 5th April 2013. Visibility was
good, with weak winds and low wave field.
A calibration dip for 8 microCATs recovered at RS1 to RS5, 8 of the microCATs to be deployed
and a spare microCAT (SN 1696) were carried out in the morning of the 6 th April while waiting for
the weather to improve sufficiently to permit us to recover RS6. The microCATs were clamped to
the CTD rosette and submerged to 3500 m. As the rosette was being brought up to the surface, three
25-minute stops were made to allow the microCATs to record at reasonably constant and uniform
conditions. The microCAT sampling rate was set to 10 seconds for this calibration dip, thus
affording about 150 samples per rosette stop. The nominal sampling depths were: 3500 m, 2500 m,
and 1500 m. Results from these calibration casts will be used, in combination with dips done on the
previous cruise, HUD2011043, to correct raw temperature, conductivity and pressure data from the
microCATs. Yuri Geshelin and John Loder, from BIO, will lead the calibration and quality control
of the microCAT and ADCP data recovered. The ADCP data, which is typically more difficult to
calibrate than CTD or BPR data, will be calibrated first. After this, a preliminary calibration of the
microCAT data will be performed using the raw CTD cast data as truth. Subsequently, once the
CTD data has been calibrated itself using the bottle samples, a final slope and offset correction will
be applied to the SBE37 microCAT measurements.
The following four tables summarise relevant information for all recoveries.
SITE
LATITUDE
(N)
LONGITUDE
(W)
DATE RECOVERED
DEPTH (m) MOORING TYPE
RS1
42 51.1523
61 38.1068
05/04/13
1106
Short
RS2
42 44.3020
61 34.4829
05/04/13
1718
Short
RS3
42 39.3558
61 27.3860
05/04/13
2325
Short
RS4
42 33.4337
61 22.2630
05/04/13
2783
Short
RS5
42 23.3777
61 16.8417
05/04/13
3428
Short
RS6
42 10.8283
61 00.3925
07/04/13
3836
Long
RS6A 42 12.3469
61 09.1772
07/04/13
3873
Short
Note. Positions were calculated from M-Cal triangulations (see SEANAV's website http://www.seanav.com/).
Echo sounder depths with assumed sound velocity of 1500 m/s.
Table 1: Moorings recovered.
5
RS1
Casabel Irid. beacon
RS2
RS3
RS4
RS5
300034012204210
RS6:
300034012152420
300034012021780
Sable Irid. beacon
SBE37 microCAT
6437
SBE37 microCAT
3682
RS6
300034012298970
300034012484560
300034012615490
RS6A:
300034012153420
4614
3709
SBE37 microCAT
6435
SBE37 microCAT
6434
SBE37 microCAT
3681
4617
3710
SBE37 microCAT
6432
SBE37 microCAT
2165
SBE37 microCAT
3713
3675
SBE37 microCAT
3680
SBE37 microCAT
3714
WHADCP
11432
Aanderaa RCM111
595
Benthos 865-A
acoustic release
47462
13.0 kHz, R:D/E:G
11433
13153
12455
11089
16405
40082
8.75 kHz; R:G
53468
8.5 kHz; R:B
47464
14.0 kHz; R:A/E:F
51819
14.5 kHz;
R:H/E:A/D:G
RS6:
805
11.25 kHz; R:D/E:E
40080
8.25 kHz; R:C/E:B
889
9.25 kHz; R:C/E:A
RS6A:
47463
13.5 kHz; R:G
SBE53 BPR
24
52
73
47
1. This current meter is BIO's and not part of the RAPID-WAVE project.
Table 2: Summary of equipment recovered
23
25
Instrument
Site
Sampling
(ensemble)
interval
(seconds)
Averaging
interval
SBE37-SM 2165 CTD/3500 m
RS5
1800
Note 1
-
26/09/2011 14:00:01
05/04/2013 20:00:01
SBE37-SMP 3675 CT/7000 m
RS6
1800
Note 1
-
28/09/2011 13:00:01
07/04/2013 20:00:01
SBE37-SMP 3680 CT/7000 m
RS6
1800
Note 1
-
28/09/2011 13:00:01
07/04/2013 19:00:04
SBE37-SMP 3681 CTD/7000 m RS3
1800
Note 1
-
29/09/2011 16:00:01
05/04/2013 16:00:02
SBE37-SMP 3682 CTD/7000 m RS1
1800
Note 1
-
29/09/2011 11:00:01
05/04/2013 12:30:01
SBE37-SMP 3709 CTD/7000 m RS2
1800
Note 1
-
29/09/2011 13:00:01
05/04/2013 14:00:03
SBE37-SMP 3710 CTD/7000 m RS4
1800
Note 1
-
26/09/2011 18:00:01
05/04/2013 17:30:02
SBE37-SMP 3713 CTD/7000 m RS5
1800
Note 1
-
26/09/2011 14:00:01
05/04/2013 20:00:02
SBE37-SMP 3714 CTD/7000 m RS6
1800
Note 1
-
28/09/2011 13:00:01
07/04/2013 19:00:03
SBE37-SM 4614 CTD/3500 m
RS6
1800
Note 1
-
28/09/2011 13:00:01
07/04/2013 13:30:01
SBE37-SM 4617 CTD/3500 m
RS6
1800
Note 1
-
28/09/2011 13:00:01
07/04/2013 14:30:00
SBE37-SM 6432 CTD/3500 m
RS6
1800
Note 1
-
28/09/2011 13:00:01
07/04/2013 15:00:01
SBE37-SM 6434 CTD/3500 m
RS3
1800
Note 1
-
29/09/2011 16:00:01
05/04/2013 16:00:01
SBE37-SM 6435 CTD/3500 m
RS6
1800
Note 1
-
28/09/2011 13:00:01
07/04/2013 14:30:01
SBE37-SM 6437 CTD/3500 m
RS1
1800
Note 1
-
29/09/2011 11:00:01
05/04/2013 12:30:01
WHADP Sentinel 11089
RS5
3600
50
pings/ensemble
1 ping/36 s
30/4/50
26/09/2011 14:00:00
50
pings/ensemble
1 ping/36 s
30/4/50
50
pings/ensemble
1 ping/36 s
30/4/50
50
pings/ensemble
1 ping/36 s
30/4/50
50
pings/ensemble
1 ping/36 s
30/4/50
50
pings/ensemble
1 ping/36 s
30/4/50
1200
300 s2
-
23/09/2011 17:50:00
04/09/2013 19:45:00
1200
300 s
2
-
23/09/2011 17:20:00
04/09/2013 21:05:00
300 s
2
-
23/09/2011 21:20:00
04/09/2013 19:45:00
300 s
2
-
23/09/2011 20:00:00
04/09/2013 19:05:00
300 s
2
-
23/09/2011 20:00:00
04/09/2013 21:25:00
300 s
2
-
23/09/2011 21:40:00
04/09/2013 19:05:00
WHADP Sentinel 11432
WHADP Sentinel 11433
WHADP Sentinel 12455
WHADP Sentinel 13153
WHADP Sentinel 16405
SBE53 23
SBE53 24
SBE53 25
SBE53 47
SBE53 52
SBE53 73
RS1
RS2
RS4
RS3
RS6
RS5
RS1
RS6
RS4
RS2
RS3
3600
3600
3600
3600
3600
1200
1200
1200
1200
Number of Time of first record (Z) Time of last record (Z)
bins/
bin size
(m)
13/04/2006 14:18:45
29/09/2011 10:00:00
13/04/2006 14:56:10
29/09/2011 13:00:00
26/09/2011 19:00:00
13/04/2006 08:45:54
29/09/2011 16:00:00
13/04/2006 09:36:03
28/09/2011 12:00:00
13/04/2008 09:33:47
1. The most recent SBE73s no longer have a tunable averaging option: each sample is calculated as the average of 4 consecutive
measurements (because of this, the fastest possible sampling rate is about 15 seconds).
2. Sensor warming up period was set to 300 seconds too. The time stamp for SBE53 samples correspond to the beginning of each
300- second averaging interval. The reference frequency measurement was set to once per week. With these settings, and taking
into account that all SBE53s were fitted with alkaline batteries, the estimated maximum battery endurance should be 805.6 days.
Table 4: Summary of instrument set up.
7
SBE37 serial
number
Date of calibration cast
Sensors
Pump
Depth rating
(m)
Notes
1696
06/04/13
CTD
No
7000
Good
2165
06/04/13
CTD
No
3500
Good. Recovered from RS5
3675
08/04/13
CT
Yes
7000
Good. Recovered from RS6
3680
08/04/13
CT
Yes
7000
Good. Recovered from RS6
3681
06/04/13
CTD
Yes
7000
Good. Recovered from RS3
3682
06/04/13
CTD
Yes
7000
Good. Recovered from RS1
3709
06/04/13
CTD
Yes
7000
Good. Recovered from RS2
3710
06/04/13
CTD
Yes
7000
Good. Recovered from RS4
3713
06/04/13
CTD
Yes
7000
Good. Recovered from RS5
3714
08/04/13
CTD
Yes
7000
Good. Recovered from RS6
4614
08/04/13
CTD
No
3500
Good. Recovered from RS6
4617
08/04/13
CTD
No
3500
Good. Recovered from RS6
6432
08/04/13
CTD
No
3500
Good. Recovered from RS6
6433
06/04/13
CTD
Yes
3500
Good
6434
06/04/13
CTD
No
3500
Good. Recovered from RS3
6435
08/04/13
CTD
No
3500
Good. Recovered from RS6
6436
06/04/13
CTD
No
3500
Good
6437
06/04/13
CTD
No
3500
Good. Recovered from RS1
8110
06/04/13
CTD
Yes
7000
Good
8111
06/04/13
CTD
Yes
7000
Good
8263
06/04/13
CTD
Yes
3500
Good
8264
06/04/13
CTD
Yes
3500
Good
8265
06/04/13
CTD
Yes
3500
Good
9021
06/04/13
CTD-DO
Yes
3500
Good
1784
07/04/13
CTD
No
7000
Good
6467
07/04/13
CTD
Yes
7000
Good
7647
07/04/13
CTD
Yes
7000
Good
8109
07/04/13
CTD
Yes
7000
Good
8110
07/04/13
CTD
Yes
7000
Good
8111
07/04/13
CTD
Yes
7000
Good
9410
07/04/13
CTD-DO
Yes
7000
Good
9411
07/04/13
CTD-DO
Yes
7000
Good
Table 3: Summary of calibration dips. Note: three 25-minute stops were made at ~3500, ~2500 and
~1500 m..
Notes on recovered instruments
1. Bottom pressure recorders
SBE53s. All 6 BPRs deployed in 2011 were recovered. Overall, their performance was quite good,
as we have become accustomed to. However, there are a few concerns, which are as follows.
Firstly, the crates in which the BPRs SBE53 23, 24, 25, 47 and 52 had been transported to BIO after
recertification at Sea Bird showed clear evidence that they had been subject to severe shock, and
some of the crates where very badly damaged. Examination of the BPRs at BIO by Rick Boyce and
Adam Hartling in September 2011 did not indicate, however, that the instruments had been badly
affected. Another serious problem with these BPRs is that all of them were reset at Sea Bird as
having an internal temperature sensor, while, in reality, they use all five an external temperature
sensor. As a result, the calibration coefficients are likely to be significantly off the mark for all these
instruments. Subsequently, Jeff Pugh and I carried out an experiment in which all these BPRs and,
in addition, the new BPR SBE53 73, were keep running for 24 hours in the geochemical laboratory
on board the Hudson. All six instruments performed reasonably well, providing reassurance as to
the integrity of the sensors in spite of the problems that likely took place during shipping from Sea
Bird to BIO.
Figure 1: Time series of bottom pressures from recovered SBE53s. The blue line traces the raw data
and the red line depicts a moving averaged version of the data calculated with a 1 day and 20
minutes averaging window.
A small problem was encountered when downloading the data from SBE53 73. The file .hex was
corrupted and it was almost two times as large as the .hex files from the other BPRs. The problem
was solved by uploading the data from this BPRs at a smaller baud rate (9600) than the one used for
the other BPRs (115200). An additional and more serious problem is that all the reference
frequencies measured during the deployment appear to be zero. Whether this is a problem with the
sampling of these frequencies or only with their recording is unclear. We have run tests on the
performance of the ovenized crystal oscillators after recovery of the BPR units using the Seaterm
command 'tsx'. These tests seem to give reasonable oscillator frequencies and so I wonder whether
the problem is with the recording or downloading of these frequencies. Sea Bird will be alerted to
this problem.
Pressure ranges in all 5 recovered sites were approximately 1.5 decibars, with trends over the period
of measurement that can be as large as 0.2 decibars per year, significantly larger than in the
previous year when the trends were on the order of ~0.1 decibars per year. This poorer performance
might in part be explained by the various problems referred to above. The BPRs will be returned to
Sea Bird for refit and calibration.
After recovery, the BPRs were kept running for several days inside the geochemical lab of the
9
Hudson in order to obtain a dry calibration against a high accuracy Digiquartz barometer. Figure 2
shows the time series of BPR and barometer pressures (left panel) and BPR temperatures right
panel) between 07-04-2013 at ~18:12:06 and 09-04-2013 at ~18:47:16. This is the period during
which all BPRs were placed in the geochemical lab. BPRs 23, 24, 47, 52 and 73 were recovered on
05-04-2013. Dry-calibration data for all of these five moorings was collected between the 05-042013 and 07-04-2013, but is not shown here. It is clear from the figure that SBE53 25 takes about
one day to adapt to laboratory temperature, which suggests that the temperature recorded is an
internal one. During the last day of calibration, all BPRs as well as the barometer evolve in
consonance, exhibiting very similar variability but separated from one another by a nearly constant
offset. Taking the barometer pressure as truth, the pressure error can be as high as 0.8 decibars.
Figure 2: Time series of pressure (left) and temperature from the 6 BPRs that were
recovered during the cruise and dry-calibrated in the geochemical laboratory. The
yellow curve on the left panel is the one for the DQ 765 barometer time series.
In 2011 similar dry tests were carried out on these BPRs before deployment although no barometer
was available for their calibration. It is interesting to note that the sign of the pressure difference
between any two BPR time series remains the same as in the dry tests of 2011 (see cruise report for
HUD11043). The SBE53 23 needs to be excluded from this inter-comparison because it was placed
upside down during the tests carried out in 2011 and, as a result, its recorded pressure at the time
was more than 2 dbar lower than the pressure of any of the other BPRs.
2. RDI Workhorse ADCPs
All ADCPs were recovered, although the ADCP at RS2 seems to have malfunctioned. No data was
recorded by this instrument. All other ADCPs provided fairly good data, and none of them run out
of batteries prematurely. The effective ADCP range decreases with depth, presumably as a result of
the decreasing number of scatterers in the water column as depth increases. The mooring length was
increased compared to previous years in order to avoid contamination of the ADCP bins in the
range >50 m by the presence of the mooring's top float. Only detailed analysis of these data back at
BIO will allow us to determine whether this change of mooring architecture worked, but a
preliminary examination seems to show an improvement. In all sites, the measured velocities are
very coherent in the vertical (see figure below). At all sites, the vertical profile of the current
appears to be somewhat distorted at a range of ~50 m. This is due to the presence of a microCAT at
that depth.
11
Figure 3: Time series of zonal velocity from ADCPs at, from top to bottom, RS1, RS3, RS4, RS5
and RS6. As a results of battery malfunction the ADCP at RS2 recorded no data.
3. SBE37 microCATs
The mooring microCAT data was summarily examined soon after recovery. All data seemed of
acceptable quality. Drift of the pressure gauges amounted to ±0.2 decibars or less in all instruments.
When drift existed, it was predominantly negative. Only the bottom microCAT at RS5 (SBE37
1806) shows a gentle drift of ~0.5 dbar. microCATs with drifts larger than 2 decibars are SBE37
1809 (-10 dbar) and SBE37 1808 (-17 dbar). The microCAT SBE37 6434 (top microCAT at RS3)
has not evident drift, but the pressure time series shows a jump of -4 dbar that occurred toward the
end of 2012. There is no indication of a similar jump in the data from SBE37 3681, which was
located about 50 m below 6434, and this suggests that the pressure jump displayed by SBE37 6434
is spurious.
4. CTD data
CTD casts were made adjacent to all six RS mooring sites. BIO are currently performing quality
control and calibration of these CTD data.
13
RS LINE ARRAY REDEPLOYMENT
Preparation of BPRs for deployment
Six BPRs are available for deployment during the cruise, although we will consider the possibility
of turning around one or more of the BPRs recovered. The BPRs are
Part #
Serial #
Batteries
Notes
5340415
5340415-0045
New alkaline batteries Poorly secured in crate. The amount of foam in the crate is not
enough to ensure that the BPR is conveniently padded and does
not move during transportation (see Figure 2). Transportation
problems are likely to have been at the root of problems
experienced with the high accuracy reference oscillator glass
metal seals which were discovered to be broken upon
examination of the BPR at SBE. All BPRs sent for
recertification to SBE (serial numbers 45, 48, 49, 50, 66)
seemed to have this problem. Previously deployed at RS2 in
HUD2010049.
5340415
5340415-0048
New alkaline batteries Poorly secured in crate (see comments for SBE53-0048 above).
Previously deployed at RS3 in HUD2010049.
5340415
5340415-0049
New alkaline batteries Poorly secured in crate (see comments for SBE53-0048 above).
Previously deployed at RS5 in HUD2010049.
5340415
5340415-0050
New alkaline batteries Poorly secured in crate (see comments for SBE53-0048 above).
Previously deployed at RS1 in HUD2010049.
5357555
5357555-0065
New alkaline batteries Newly bought BPR (2013). This BPR was bought directly by
NOC and shipped to BIO ahead of the cruise. It is the only BPR
with an internal temperature sensor. All other BPRs are
equipped with high accuracy external temperature sensors.
Never deployed.
5353201A 5353201-0066
New alkaline batteries Poorly secured in crate (see comments for SBE53-0048 above).
Previously deployed at RS4 in HUD2010049.
Table 4: Summary of SBE53 BPRs that were made ready for deployment.
The six BPRs were set up for dry calibration. The dry calibration consists in having a BPR running
out of the water in the vertical position (i.e., with the cable connectors pointing upwards)
concurrently with a very high accuracy barometer, so that the pressures recorded by both systems
can be compared and the BPR's pressure corrected accordingly. All BPRs were configured to use
the same settings as in a normal deployment (so that the accuracy and precision of the
measurements are exactly the same as during a deployment) and them left to run for about 24 hours.
The only differences in the BPRs configuration were as to the start times. Two of them (SNs 50 and
48) were set to start at 1655 GMT, while the rest (SNs 66, 65, 49 and 45) were set for 1855 GMT.
The reason for this discrepancy is simply a fortuitous delay that prevented us from having all BPRs
set up before the intended initial start time (i.e., 1655 GMT). Another difference between these
BPRs is that SN 65 has an internal temperature sensor while all others are equipped with a more
accurate external temperature sensor. The barometer (a Paroscientific Model 765-15A Pressure
Standard, SN 24004, with a range of 0-15 psi) was set to start recoding pressure at ~1910 GMT.
The sampling rate was set to 1 second. The barometer records internally every single sample. The
barometer data can subsequently be downloaded to a computer using Digiquartz data download
software. A quirk of either the recording or data donwload software of the Digiquartz barometer
seems to be that an 'hour:minute:second' time stamp is not written when the time is 00:00:00 (i.e.,
midnight). For example, this is how the output file looked like near midnight on the 3rd April 2013:
16685,03/04/2013 23:59:59,1006.8977,hPa,N
16686,04/04/2013,1006.8977,hPa,N
16687,04/04/2013 00:00:01,1006.8992,hPa,N
The time component of the date-time stamp is gone. This causes problems when reading the output
file with Matlab. The “faulty” line was manually corrected by adding the right time to it. Figure 1
shows the time series of pressure and temperatures from all BPRs and high-accuracy barometer
between approximately 1909 GMT on 03-04-2013 and 2100 on 04-04-2013. Note that each BPR
sample consist in a 5-minute averaged pressure taken every 20 minutes. In contrast the barometer
samples are point measurements taken every second.
Figure 4: Time series of pressure (left) and temperature from the 6 BPRs that were set
up ready for deployment.
We note the maximum pressure difference between the different sensors is on the order of 0.1 dbar,
which is significantly smaller than the nominal quoted accuracy for these instruments of ~0.7 dbar
(0.01% of the full scale, which is 10000 psi, or ~6895 dbar). Compared to the Digiquartz barometer,
whose nominal accuracy is 0.008% of the range (i.e., 0.0008 dbar) and is used here as a reference,
the SBE53 perform fairly well in following pressure variations on the order of 1 cm or so. In
contrast, the accuracy of the temperature sensor is puzzlingly low. The nominal accuracy quoted by
SBE for their high-accuracy temperature sensors is 0.002 oC. However the maximum temperature
difference between sensors is of about 0.5 oC. Clearly, something is not quite right. SBE will have
to be consulted about this problem. When these BPRs are recovered in 18 month's time, the same
procedure will be followed in order to obtain an end-point calibration.
15
Figure 5: An example of the way in which the recertified SBE53s where shipped to BIO. Note how
the top (left) white plastic bar has deformed the protective foam in the crate and is partly embedded
in it. At the same time, there is a large gap between the bottom (right) white bar and the piece of
foam glued to the crate on the right end. Clearly, the BPR can easily slip up and down (left to right)
inside the crate. There is evidence that such slippage has occurred, as the foams on both ends of the
crate have been markedly reshaped through contact with the white end plastic bars of the BPR. The
protection against shocks and abrupt motion afforded by this way of packing the BPRs is obviously
inadequate.
Joel Reiter from SeaBird advised on a test that is useful to run in order to verify the performance of
the SBE53 reference crystals that are used to correct the pressure oscillator. The test consists in
typing 'tsx' in the command line while connected to a BPR, which produces the following kind of
output (from SBE53 45 in this case, just a couple of hours before it was deployed):
4000033.3607 20883 0.19 09 Apr 2013 11:20:51
4000033.6804 20767 -0.01 09 Apr 2013 11:22:55
4000032.9874 20597 -0.01 09 Apr 2013 11:25:00
4000032.2940 20430 -0.01 09 Apr 2013 11:27:04
4000031.6540 20278 -0.01 09 Apr 2013 11:29:09
4000031.0940 20143 -0.01 09 Apr 2013 11:31:13
4000030.5604 20021 -0.01 09 Apr 2013 11:33:18
4000030.0806 19909 -0.00 09 Apr 2013 11:35:22
4000029.6273 19804 -0.00 09 Apr 2013 11:37:26
4000029.2003 19706 -0.00 09 Apr 2013 11:39:31
4000028.8006 19611 -0.01 09 Apr 2013 11:41:35
4000028.4006 19521 -0.01 09 Apr 2013 11:43:40
4000028.0006 19433 -0.00 09 Apr 2013 11:45:44
4000027.6272 19342 -0.01 09 Apr 2013 11:47:49
4000027.4561 19292 -0.02 09 Apr 2013 11:49:53
A dozen lines or so are apparently needed to carry out a proper evaluation. This output can then be
compared with similar data that SeaBird engineers produce during recertification tests. The key
comparison is in the first two columns. The first column is the low power oscillator as measured
against the reference and the second is the temperature frequency.
Preparation of microCATs for deployment (calibration dips)
Prior to their deployment, calibration dips were carried out for all microCATs. Some of these dips
included both fresh microCATS, ready for deployment, and microCATs just recovered. The
microCATs were clamped to the CTD rosette and dipped to ~3500 m. On its ascent, the rosette was
stopped for 25 minutes at ~3500 m, 2500 m and 1500 m. The microCAT sampling interval was 10
seconds. The objective of a calibration dip is to obtain simultaneous conductivity, temperature and
pressure data from both the microCATs and the CTD system. The CTD system is frequently
calibrated against temperature, salinity and pressure standards and, therefore, its data is of high
accuracy and precision. The CTD data are used to calibrate the microCAT measurements.
Combining a pre-deployment calibration dip, such as the one described here, with a postdeployment dip, it is possible to calibrate the microCAT data to an accuracy comparable to that of
the ship's CTD system. A summary of the calibration dips carried out can be found in Table 3.
The agreement in temperature between microCATs is very good, with a temperature spread that is
not larger than 0.005 oC at any depth. The spread in conductivity is 0.001 S/m, and that in pressure
in 40 dbar. In the second calibration dip, only fresh microCAT were deployed. Their spread in
pressure was of only 10 dbar, compared to the 40-dbar spread of the first calibration dip, which
combined fresh and recovered microCATs. It is the recovered microCATs that contribute the most
to the spread in pressure, bringing it up to the quoted 40 dbar (see Figures 6,7 and 8). The existence
of this relative large differences in pressure illustrates why it is so important to carry out this type of
calibration, specially on recovered microCATs. However, note that the pressure spread observed in
the fresh microCATs, while consistent with the manufacturer's specification, is still quite large. The
calibration will help to reduce such spread by, nominally, an order of magnitude.
17
Figure 6: Results from the calibration dip done on the 6 th April 2013. Each panel includes data from all the
microCATs (left: temperature; centre: conductivity; right: pressure). The red curves correspond to microCATs
recovered at RS1 to RS5. The black curves are for fresh microCATs (see Table 3).
Figure 7: Results from the calibration dip done on the 7th April 2013. Each panel includes data from all the
microCATs (left: temperature; centre: conductivity; right: pressure). See Table 3.
Figure 8: Results from the calibration dip done on the 8th April 2013. Each panel includes data from all the microCATs
(lef: temperature; centre: conductivity; right: pressure). The microCATs calibrated here are those recovered from the
RS6 mooring. See Table 3.
SITE
LATITUDE
(N)
LONGITUDE
(W)
RS1
42 51.1240
RS2
DATE & TIME
AT
DEPTH (m) MOORING TYPE
BOTTOM
SV=1489 m/s
61 38.0330
09-04-2013, 11:29 Z
1081
Short
42 44.3112
61 34.4219
09-04-2013, 14:14 Z
1698
Short
RS3
42 39.3633
61 27.4953
08-04-2013, 22:28 Z
2280
Short
RS4
42 33.3927
61 22.4997
08-04-2013, 18:55 Z
2724
Short
RS5
42 23.8300
61 13.3595
08-04-2013, 15:34 Z
3440
Short
RS6
42 10.8822
61 00.2514
07-04-2013, 20:15 Z
3812
Short
Note. Positions were calculated from M-Cal triangulations (see SEANAV's website http://www.seanav.com/).
All times record the moment when the mooring anchor hit bottom. Echo sounder depths with assumed sound
velocity of 1489 m/s.
Table 5: Moorings deployed.
19
The following table includes the serial number of all the instruments, beacons and releases deployed
in the line. Mooring schematics can be found in the Appendix.
RS1
Casabel Irid. beacon
RS2
300034012722800
300034012126050
RS3
RS4
RS5
RS6
300234060527560
300234060522560
300034012204160
300034012482560
Sable Irid. beacon
SBE37 microCAT
9021
9410
9411
6436
8110
6467
SBE37 microCAT
6433
8263
8264
8265
8109
8111
WHADCP
13983
19080
13873
10941
13874
13592
Benthos 865-A
acoustic release
59519
40083
59437
40081
54935
44302
47459
59434
59518
40047
59433
51801
SBE53 BPR
50
45
48
66
49
65
Table 6: Summary of equipment deployed
Instrument
Site
Sampling
(ensembl
e)
interval
(seconds)
Averaging
interval
Number of Time of first record Time of last record (Z)
bins/
(Z)
bin size (m)
SBE37-SMP 9021
CTD-DO/3500 m
RS1
3600
Note 1
-
09/04/13 10:00
SBE37-SMP 6433 CTD/3500 m
RS1
1800
Note 1
-
09/04/13 10:00
SBE37-SMP 9410
CTD-DO/7000 m
RS2
3600
Note 1
-
09/04/13 13:00
SBE37-SMP 8263 CTD/3500 m
RS2
1800
Note 1
-
09/04/13 13:00
SBE37-SMP 9411
CTD-DO/7000 m
RS3
3600
Note 1
-
08/04/13 20:00
SBE37-SMP 8264 CTD/7000 m
RS3
1800
Note 1
-
08/04/13 20:00
SBE37-SM 6436 CTD/3500 m
RS4
1800
Note 1
-
08/04/13 16:00
SBE37-SMP 8265 CTD/3500 m
RS4
1800
Note 1
-
08/04/13 16:00
SBE37-SMP 8110 CTD/7000 m
RS5
1800
Note 1
-
08/04/13 11:00
SBE37-SMP 8109 CTD/7000 m
RS5
1800
Note 1
-
08/04/13 11:00
SBE37-SMP 6467 CTD/7000 m
RS6
1800
Note 1
-
07/04/13 17:00
SBE37-SMP 8111 CTD/7000 m
RS6
1800
Note 1
-
07/04/13 17:00
WHADP Sentinel 13983
RS1
3600
50
pings/ensemble
1 ping/36 s
30/4/50
09/04/13 11:00
WHADP Sentinel 19080
RS2
3600
50
pings/ensemble
1 ping/36 s
30/4/50
09/04/13 12:00
WHADP Sentinel 13873
RS3
3600
50
pings/ensemble
1 ping/36 s
30/4/50
12:00:00
WHADP Sentinel 10941
RS4
3600
50
pings/ensemble
1 ping/36 s
30/4/50
08/04/13 17:00
WHADP Sentinel 13874
RS5
3600
50
pings/ensemble
1 ping/36 s
30/4/50
08/04/13 12:00
WHADP Sentinel 13592
RS6
3600
50
pings/ensemble
1 ping/36 s
30/4/50
07/04/13 18:00
SBE53 50
RS1
1200
300 s2
-
04/04/13 23:55
2
-
09/04/13 11:553
SBE53 45
RS2
1200
300 s
SBE53 48
RS3
1200
300 s2
-
04/04/13 23:55
1200
300 s
2
-
04/04/13 23:55
300 s
2
-
04/04/13 23:55
300 s
2
-
04/04/13 23:55
SBE53 66
SBE53 49
SBE53 65
RS4
RS5
RS6
1200
1200
.1. The most recent SBE73s no longer have a tunable averaging option: each sample is calculated as the average of 4 consecutive
measurements (because of this, the fastest possible sampling rate is about 15 seconds).
.2. Sensor warming up period was set to 300 seconds too. The time stamp for SBE53 samples correspond to the beginning of each
300- second averaging interval. The reference frequency measurement was set to once per week. With these settings, and taking
into account that all SBE53s were fitted with alkaline batteries, the estimated maximum battery endurance should be 805.6 days.
.3. This BPR was set to start later because it was used on the 9 th April to run a test of its crystal oscillator, which required to stop the
BPR and then restart it again after the test was completed.
Table 7: Summary of instrument set up.
21
APPENDIX. MOORING DIAGRAMS
Deployments 2011
23
25
27
Deployments 2013
29
31
33
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