VisualWeather™ Software
Version 3.1
Revision: 4/11
C o p y r i g h t © 2 0 0 1 - 2 0 1 1
C a m p b e l l S c i e n t i f i c , I n c .
License for Use
This software is protected by United States copyright law and international
copyright treaty provisions. The installation and use of this software constitutes
an agreement to abide by the provisions of this license agreement.
Campbell Scientific grants you a non-exclusive license to use this software in
accordance with the following:
(1) The purchase of this software allows you to install and use the software on
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(2) This software cannot be loaded on a network server for the purposes of
distribution or for access to the software by multiple operators. If the
software can be used from any computer other than the computer on which
it is installed, you must license a copy of the software for each additional
computer from which the software may be accessed.
(3) If this copy of the software is an upgrade from a previous version, you
must possess a valid license for the earlier version of software. You may
continue to use the earlier copy of software only if the upgrade copy and
earlier version are installed and used on the same computer. The earlier
version of software may not be installed and used on a separate computer
or transferred to another party.
(4) This software package is licensed as a single product. Its component parts
may not be separated for use on more than one computer.
(5) You may make one (1) backup copy of this software onto media similar to
the original distribution, to protect your investment in the software in case
of damage or loss. This backup copy can be used only to replace an
unusable copy of the original installation media.
This software may not be sold, included or redistributed in any other software,
or altered in any way without prior written permission from Campbell
Scientific. All copyright notices and labeling must be left intact.
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The following warranties are in effect for ninety (90) days from the date of
shipment of the original purchase. These warranties are not extended by the
installation of upgrades or patches offered free of charge.
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for use, or that the software or documentation are error free, or that the
operation of the software will be uninterrupted.
Campbell Scientific will either replace or correct any software that does not
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manual with a corrected copy of the software or corrective code. In the case of
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Scientific will correct errors without charge by providing new media, addenda,
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documentation within a reasonable time, it will either replace the software with
a functionally similar program or refund the purchase price paid for the
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This warranty does not cover any software that has been altered or changed in
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responsible for problems caused by computer hardware, computer operating
systems, or the use of Campbell Scientific’s software with non-Campbell
Scientific software.
Licensee’s sole and exclusive remedy is set forth in this limited warranty.
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the purchase price paid by the licensee.
VisualWeatherTM Software
Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
the Adobe Acrobat® bookmarks tab for links to specific sections.
1. Introduction..................................................................1
1.1 Background...............................................................................................2
1.2 What’s New in VisualWeather 3.1 ...........................................................2
2. Installation....................................................................2
2.1 Upgrades...................................................................................................2
2.1.1 For Users Upgrading from VisualWeather 2 ..................................2
2.1.2 For Users Upgrading from VisualWeather 1 ..................................3
2.2 Hardware and Software Requirements .....................................................3
2.3 Configuration of TCP/IP and Telephony Services ...................................4
3. Starting Out ..................................................................4
3.1 Before You Begin.....................................................................................4
3.2 Running VisualWeather ...........................................................................4
3.3 Getting Help .............................................................................................5
4. The Home Screen ........................................................5
5. Configure Weather Station .........................................5
5.1 Configuring a New Weather Station in VisualWeather............................5
5.2 After Configuring a Weather Station........................................................6
5.3 Editing an Existing Weather Station Configuration .................................6
6. Connect ........................................................................6
6.1 Manually Connecting to a Weather Station ..............................................6
6.1.1 Maximum Connection Time ...........................................................7
6.2 Monitoring Current Conditions ................................................................8
6.3 Monitoring Station Status .........................................................................9
6.4 Field Monitor..........................................................................................11
6.5 Manually Collecting Data.......................................................................11
6.6 Setting a Weather Station Clock.............................................................11
6.7 Sending/Retrieving Programs to a Weather Station ...............................12
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VisualWeatherTM Software Table of Contents
7. Reports .......................................................................12
7.1 Manually Generated Reports ................................................................. 12
7.2 Report Parameters .................................................................................. 13
7.2.1 Wind Rose.................................................................................... 13
7.2.2 Evapotranspiration (ETo)............................................................. 15
7.2.3 Crop Water Need.......................................................................... 16
7.2.4 Growing Degree Days and Growing Degree Days 2 ................... 17
7.2.5 Chill Hours ................................................................................... 17
7.2.6 Custom Reports ............................................................................ 18
7.2.7 Custom X-Y Reports.................................................................... 19
7.2.8 Custom GDD Reports .................................................................. 20
7.3 Batch Reports......................................................................................... 22
7.3.1 New .............................................................................................. 23
7.3.2 Edit ............................................................................................... 25
7.3.3 Run ............................................................................................... 25
7.3.4 Delete ........................................................................................... 25
8. Station Data ................................................................25
9. Monitoring the Data Collection Status .....................31
10. Weather Station Network ........................................33
11. Data Mapping ...........................................................34
11.1 Report Field Mapping .......................................................................... 34
11.2 Real Time Field Mapping .................................................................... 37
12. Web Output............................................................................................ 37
13. Exporting and Importing Data.................................39
13.1 Exporting Data ..................................................................................... 39
13.2 Importing Data ..................................................................................... 40
14. Backup/Restore Network ........................................40
15. Programming Custom Weather Stations ...............41
16. Advanced Features..................................................41
16.1 Run On Startup .................................................................................... 41
16.2 LogTool ............................................................................................... 41
16.2.1 Log Types................................................................................... 41
16.2.2 Using LogTool ........................................................................... 42
16.2.3 Saving Logs to File .................................................................... 42
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VisualWeatherTM Software Table of Contents
Appendices
A. Evapotranspiration, Vapor Pressure Deficit,
and Crop Water Needs ......................................... A-1
A.1 Evapotranspiration .............................................................................. A-1
A.2 Vapor Pressure Deficit of the Air ....................................................... A-8
A.3 Crop Water Needs, Crop Coefficients ................................................ A-9
B. Growing Degree Days (GDD) and
Pest Emergence.................................................... B-1
B.1 Growing Degree Days..........................................................................B-1
B.1.1 Method .......................................................................................B-1
C. Dew Point................................................................. C-1
C.1 Dew Point.............................................................................................C-1
C.1.1 Method .......................................................................................C-1
C.2 References............................................................................................C-1
D. Wind Chill................................................................. D-1
D.1 Wind Chill .......................................................................................... D-1
D.1.1 Method ...................................................................................... D-1
D.2 References........................................................................................... D-1
E. Chill Hours ............................................................... E-1
E.1 Chill Hours ...........................................................................................E-1
E.1.1 Method........................................................................................E-1
F. Heat Index ................................................................ F-1
F.1 Heat Index ............................................................................................ F-1
F.1.1 Method........................................................................................ F-1
F.2 References ............................................................................................ F-1
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VisualWeatherTM Software Table of Contents
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VisualWeather™ Software
1. Introduction
VisualWeather software is designed to work with Campbell Scientific's preconfigured weather station models ET106, ET107, Toro T107, and MetData1,
or custom-configured weather stations. This software will allow you to:
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Create and send programs to one or more weather stations.
Select a mode of communication (e.g., phone modem or RF) for each
weather station.
Define a data retrieval schedule for each station.
Connect to any weather station that has been configured with
VisualWeather.
View a graphical display of a weather station’s current weather conditions.
Print a summary of each weather station’s configuration.
Monitor the "health" (e.g., battery voltage, internal temperature) of each
weather station.
View and print preformatted reports (tables and graphs) from the data
retrieved from each weather station.
Perform post-processing on retrieved data to produce special
meteorological and agricultural reports (e.g., evapotranspiration,
dewpoint).
Set up a schedule to automatically print reports (Batch Reports).
Export retrieved data to an ASCII file so it can be imported into a
spreadsheet or other software package for further data processing.
These tasks can be accomplished by clicking a few buttons and following the
on-screen instructions. It requires no computer experience or in-depth
technical knowledge of the weather station equipment. We hope all users—
novices or experts—will find VisualWeather a very easy to use, yet powerful,
tool for managing a weather station network.
NOTE
This software is primarily designed to calculate quantities, such
as evapotranspiration (ETo), crop water needs, and growingdegree-days, which are important to the agricultural community.
This software expects that your weather station has at least a
‘full set’ of sensors, namely sensors that measure temperature,
relative humidity, precipitation, solar radiation, and wind
speed/wind direction. If your weather station does not measure
these weather conditions, then you may not be able to utilize the
full potential of this software. For example, if your station does
not have a humidity sensor, then you will not be able to get
reports on ETo or crop water needs.
It is best to consult a CSI applications engineer who will advise
you on sensors required for your needs.
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VisualWeather™ Software
1.1 Background
Each weather station consists of a datalogger and a group of sensors. The
sensors are designed to measure environmental factors such as air temperature
or solar radiation. The datalogger measures the sensors and processes and
stores the results. The stored results (final storage data) can be retrieved with a
PC using communication software.
Dataloggers must be "told" (that is, programmed) when and how to measure the
attached sensors, process these measurements, and store the information in final
storage. Datalogger programming can be a formidable task for many users.
However, when using VisualWeather with ET106, ET107, Toro T107, and
MetData stations, you simply select the sensors connected to the weather station
and the program is generated for you! For users with stations other than our
preconfigured weather stations, VisualWeather supports custom weather station
configurations. Short Cut for Windows is included in VisualWeather (Tools |
Short Cut), so that programs can easily be created for any datalogger type. Once
the program is generated and transferred to the datalogger, variables or input
locations in the datalogger are associated with the measurement values required
by the VisualWeather database for generation of reports.
1.2 What’s New in VisualWeather 3.1
VisualWeather 3.1 includes the following enhancements from VisualWeather
2.3:
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Support for the ET107 and Toro T107
Enhanced Station Data screens
Improved web output support
Improved FTP support
Enhanced Station Status window
Changes to the database for faster report generation
Global Units option which controls output units for reports and Station
Data screens
The user now has the ability to set the units used for barometric pressure
and wind speed
VisualWeather can now display the user interface component text (for
buttons, dialog boxes, etc.) in an alternate language, if a separate
VisualWeather language package has been installed
2. Installation
2.1 Upgrades
2.1.1 For Users Upgrading from VisualWeather 2
If you have VisualWeather 2 installed on your computer, when you run the
installation the existing version will be updated with the new files.
VisualWeather will continue to use the existing stations, databases, reports,
etc.
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VisualWeather™ Software
2.1.2 For Users Upgrading from VisualWeather 1
VisualWeather 3.X will not upgrade an existing VisualWeather 1 installation.
Significant changes were made to the database structure for VisualWeather 2.
Existing VisualWeather databases and reports are not compatible with, nor will
they import into, the new software. If VisualWeather 1 is detected on your
computer system during installation of VisualWeather 3.X, you will be
required to install the program executable and supporting files in a different
directory, as well as choose a different working directory.
The default installation directory for VisualWeather 3.X is C:\Program
Files\Campbellsci\VisualWeather. The default working directory for
VisualWeather 3.X (the directory in which all the data and report files are
stored) is C:\Campbellsci\VisualWeather. (Note the lack of a space in the
VisualWeather name; previous installations used the name Visual Weather.)
Subfolders are created in the working directory for the database (DataBase),
exported ASCII files (Export), custom images that are associated with stations
(Images), program files that are generated for preconfigured weather stations
during setup (ProgFiles), reports that are generated when using VisualWeather
(Reports), the RTMC projects used for Station Data (RTMC), and web output
(Web). A Sys directory also contains setup information and log files for your
copy of VisualWeather.
While VisualWeather 1 did not include the Short Cut program generator, it is
included in other Campbell Scientific software packages and also offered as a
stand-alone download from our web site. Therefore, you may already have a
copy on your computer. VisualWeather will update the existing version of
Short Cut. Any files created using previous versions of Short Cut for
Windows will be compatible with this current version. Additionally, if this
version of VisualWeather is uninstalled, the Short Cut program generator will
remain installed on the computer if it was installed prior to the installation of
VisualWeather.
2.2 Hardware and Software Requirements
The recommended minimum hardware for VisualWeather is a computer
running Windows XP, Vista, or 7.
NOTE
If you need to contact weather station(s) in remote locations,
then you may also need RF modems and radios or an analog
phone line and a phone modem. VisualWeather can detect
modems installed on your computer provided they were
configured in your computer’s Window environment. During
configuration of a new weather station you will find it
convenient to select the detected modem.
NOTE
Some newer computers have USB ports instead of serial ports
for communication with other devices. Communication using
VisualWeather requires serial communication. If your computer
has only a USB port, you will need a USB to serial port adapter.
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VisualWeather™ Software
To install the software, insert the VisualWeather CD into the CD ROM drive
of your computer. The installation process should begin automatically. If it
does not begin, access your CD ROM drive and double-click the SETUP.EXE
file. Follow the on-screen instructions to complete the installation.
2.3 Configuration of TCP/IP and Telephony Services
TCP/IP and Telephony services must be installed and enabled on the computer
for VisualWeather to run. To determine if both of these services are installed
and enabled, access the Windows Control Panel (Start | Control Panel). From
the Control Panel, open Administrative Tools and choose Services. The list of
installed services is typically displayed in alphabetical order. Review the list
for entries titled TCP/IP and Telephony.
The Startup Type for each service should be listed as "Automatic" or
"Manual". If either of the services is installed but listed as "Disabled", right
click the service to bring up a floating menu. Select Properties, and on the
General tab, change the Startup Type to Automatic or Manual. If a service is
not installed refer to the Windows operating system help for installation
information. In Windows XP, the Help & Support Center can be opened by
selecting the My Computer icon on the desktop and pressing F1. Typing in
TCP/IP Service in the Search field will display a link to “Install Simple
TCP/IP Services”. Typing in Telephony Service will display a link to “Add a
Telephony Service Provider”.
NOTE
You may need to contact your IT department for complete
information for configuring these services.
3. Starting Out
3.1 Before You Begin
Before configuring a weather station in VisualWeather, the following tasks
must be completed:
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Install VisualWeather on your computer.
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Install a weather station with the desired sensors connected properly to the
station. (Please refer to the Weather Station manual.)
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Charge the battery supplying power to the station (12 Volts DC).
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Ensure communication hardware (e.g. modem, phone line, radio, etc.) is
connected properly and functioning.
3.2 Running VisualWeather
To run the VisualWeather Software, click the desktop icon (if it was added to
the desktop during the install) or select Programs | Campbell Scientific |
VisualWeather | VisualWeather from the Windows Start menu.
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VisualWeather™ Software
3.3 Getting Help
VisualWeather has a complete on-line help system. Most screens have a Help
button that, when pressed, will bring up help about the screen. In addition,
help for any screen can be displayed by pressing the F1 key on your computer.
A Help file Table of Contents, an Index, and a Search function can be
displayed by selecting VisualWeather Help from VisualWeather's main menu.
4. The Home Screen
The VisualWeather Home screen is the starting point for all tasks in the
software:
The most common tasks (configuring a weather station, connecting, creating
reports, displaying station data, monitoring data collection status, and viewing
the network) are shown as headings on this screen. Less common tasks (batch
reports, importing data, exporting data) are accessible from VisualWeather’s
menu.
5. Configure Weather Station
5.1 Configuring a New Weather Station in VisualWeather
Configuring your weather station in VisualWeather is simple using the
EZSetup Wizard. To begin configuring a weather station select Configure
Weather Station or Network | Configure Weather Station from the main menu
of the Home screen.
The EZSetup Wizard will walk you through each step in the setup process. If
help is needed on a specific screen, press the Help button at the bottom right of
the window. To move forward and backward in the EZSetup wizard use the
Previous and Next buttons. At any time you can click the Cancel button.
This will cancel configuring the weather station.
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VisualWeather™ Software
After you have progressed through all steps of the wizard, press the Finish
button to save the configuration and return to the main VisualWeather window.
5.2 After Configuring a Weather Station
After setting up your weather station, VisualWeather will automatically collect
data at the intervals specified (if scheduled collection is enabled). If batch
reports have been created (see Batch Reports section 7.3), VisualWeather will
automatically create reports using the collected data.
Note, however, that VisualWeather must be running for automatic scheduled
data retrieval and batch reports to be performed. If for some reason you must
close VisualWeather, these tasks will resume once the software is restarted.
Data will not be lost unless the software has been closed a sufficient amount of
time for the weather station to begin overwriting its oldest data with new data.
This can be anywhere from 10 to 30 days depending upon the station type
selected. It is prudent to retrieve data at least daily to protect against loss of
data.
Data collection from the stations can be verified by viewing the collection
schedule. See the collection schedule by selecting Collection Status from the
home screen or choosing Network | Collection Status from the VisualWeather
menu (see Monitoring the Data Collection Status section 9).
5.3 Editing an Existing Weather Station Configuration
Weather stations that have been set up in VisualWeather can be edited by
selecting Network | Edit Weather Station from the VisualWeather menu and
selecting a station from the resulting dialog box. This will open the EZSetup
Wizard for the station. To navigate to a specific section of the setup, select the
section from the Progress panel on the left side of the Wizard.
6. Connect
6.1 Manually Connecting to a Weather Station
In addition to performing automatic scheduled data retrieval, you can connect
to a weather station manually and perform system maintenance, monitor
current weather parameters, or retrieve data.
To connect to a weather station, select the Connect heading or Connect |
Connect from the main menu of the Home screen. The Connect to a Station
screen will be shown.
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VisualWeather™ Software
All weather stations that have been configured using VisualWeather will be
listed on the left side of the screen under the Station Selection field. Select the
weather station you wish to communicate with and click the Connect button.
VisualWeather will attempt to communicate with the weather station. Once
connected, the Connection Status will display Connected and other buttons on
the window will be enabled.
The amount of time that your computer has been connected to the weather
station is indicated by the Connection Time field at the bottom left part of the
screen. When communication is initiated manually, it will be maintained until
you reach the Maximum Connection Time (see below), you click the
Disconnect button, you return to the Home screen, or you close
VisualWeather. Note that whenever you are connected to a weather station,
the weather station uses more power, phone connections remains active (thus,
phone costs may be incurred), no other station on that COM port can be
contacted for data, and no other users can connect to the weather station.
6.1.1 Maximum Connection Time
Because phone modem connections can be costly and communication with a
weather station can put a heavy load on the station’s power supply, by default,
any manual connection to the station will be terminated automatically after
five minutes.
The Maximum Connection Time group box allows you to change the amount
of time after which VisualWeather will terminate communication, or to
override this feature completely. Select the Stay connected for X minutes
option if you wish to have the connection disconnected automatically after a
specified amount of time. If you wish to be connected until you manually
disconnect, select the Stay connected until I disconnect option.
Communication with the weather station will be maintained until you click the
Disconnect button.
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VisualWeather™ Software
6.2 Monitoring Current Conditions
Current weather conditions can be viewed after connecting to a weather
station. Click the Current Conditions button to show the Current Conditions
Screen.
The data displayed will be based upon the sensors that were selected when the
weather station was configured. Custom stations will show only those values
that were set up in the Data Files/Mapping section when configuring the
weather station (see Section 11.2 Real Time Field Mapping). The units used
will be based on the options chosen from VisualWeather’s Tools | Options
menu item.
The data that is displayed is the same as that displayed by Station Data. (See
Section 8 Station Data for more information.) However, when monitoring
current conditions through the connect window, data will only be displayed for
the station to which you are connected. Also, VisualWeather will actively
collect data on a one-second interval to be displayed when monitoring current
conditions. (Data displayed by Station Data must be collected manually or on a
schedule.)
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VisualWeather™ Software
6.3 Monitoring Station Status
When you have a connection established with a weather station, you can view
the station’s status. This can be done by clicking the Station Status button.
The Station Status window has three tabs. The Summary tab provides an
overview of important status information in the datalogger, including the
information about the datalogger model and its firmware, program details,
battery voltage levels, and card memory (if one is present). Right click within
this window to display a menu for printing the summary or saving this
information in a file.
NOTE
Only the Summary tab is available for array-based dataloggers.
The Table Fill Times tab lists the tables in the datalogger, along with the
maximum number of records the table can hold, the estimated amount of time
that it will take the table to fill, and the estimated date and time that the table
will fill based on the time the datalogger program was downloaded and the
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VisualWeather™ Software
table size. A data table can be reset from this window by pressing the Reset
Tables button.
NOTES
No Table Fill Time statistics will be shown for a CR200 Series
datalogger, because they cannot be calculated for this datalogger
model.
For the CR10XTD, CR10XPB, CR510TD, CR510PB,
CR23XTD, and CR23XPB, the Time of Fill will not be shown
and you will not have the option to Reset Tables.
Resetting a table will erase the data in the datalogger and in the
data cache.
The Status Table tab lists all of the status table fields in the datalogger along
with their values. By default, all of the fields in the status table are displayed.
To select only certain status data to be viewed, press the Select Fields button.
This will display a list of the status data available in the datalogger. Select one
or more of the fields and then press OK. The current values will be displayed
in the table. If you select a cell within the status table and right click, a short
cut menu will be displayed. From this menu you can view/edit a value (if it is a
writable value).
Press Refresh to prompt VisualWeather to query the datalogger and update the
values again. This refresh option is also available from the right click menu.
Refer to individual datalogger manuals for a list of fields included in the status
table for each datalogger and a description of each.
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VisualWeather™ Software
6.4 Field Monitor
Clicking the Field Monitor button will bring up a screen that allows you to
view the numeric values for a table.
Select the table you want to view from the Table list box; the values for that
table are displayed in the cells. Right-clicking on a value and then selecting
View/Edit will display the value in a separate dialog box and allow you to
change the value (if it is editable).
NOTE
For array-based dataloggers, there may be long delays before the
values in the Field Monitor are updated when data collection is
occurring. No updates can be done until data collection is
completed.
6.5 Manually Collecting Data
To manually collect data from a weather station, click the Start button in the
section of the screen titled Manual Data Collection. You will see the
progress bar fill as VisualWeather is retrieving data. You can stop data
retrieval at any time by clicking the Stop button.
6.6 Setting a Weather Station Clock
The station’s clock and the PC clock times are shown on the Connect screen.
When you click the Set Station Clock button, the station’s clock will be set to
the PC clock with the entered Time Zone Offset.
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VisualWeather™ Software
NOTE
It is nearly impossible to synchronize the two clocks exactly,
since it takes time to transfer the clock setting to the weather
station.
6.7 Sending/Retrieving Programs to a Weather Station
The name of the program currently running in the weather station is displayed
in the Station Program Group box.
For debugging purposes it may be necessary to retrieve the program from the
weather station. Click the Retrieve button and choose the location to save the
file. The program will be retrieved from the weather station.
To send a new program to a datalogger, edit the configuration for a weather
station by selecting Network | Edit Weather Station from the main
VisualWeather menu (select the appropriate station from the resulting dialog
box). Click Send Program from the EZSetup Wizard’s Progress panel to
navigate quickly to the Send Program page.
7. Reports
7.1 Manually Generated Reports
To generate reports, select the Reports heading or the Reports | Generate
Reports menu item from the Home screen. The Report Selection Screen will
be shown to allow you to select the type of report, time range of data to use,
and reports to generate.
Select a current or past weather station. Current weather stations are those
currently part of the network. Past weather stations are those that have been
deleted from the network.
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VisualWeather™ Software
After a station is selected, use the option buttons to select the time range that
the report should cover. Note that VisualWeather will not let you enter a time
range for data that is outside of what is currently available in the database. The
following report options are available:
24 hour
Creates a 24 hour report, with a user-specified start date and time.
As the start parameters are entered, the end date and time change
accordingly to reflect a 24 hour period.
1 day
Creates a 24 hour report for a specific date, which begins and ends
at midnight.
7 day
Creates a 7 day report, which begins on midnight of the start date
and ends at midnight on the end date. As the start date is entered,
the end date changes accordingly to reflect the 7 day period.
1 month
Creates a report for a specified month, which begins on midnight
of the first day of the month and ends at midnight on the last day of
the month.
Custom
Creates a report that starts at midnight of the specified start date,
and ends at midnight of the specified end date.
Last, select the reports you wish to generate. Any reports that cannot be
generated for the specific weather station type are disabled. The reports that
are available for a custom weather station are based on the report parameters
that were mapped to data fields during the configuration of the weather station
(see 11.1 Report Field Mapping). Some reports require additional parameters
that need to be set (see 7.2 Report Parameters). These parameters can be set
and changed at any time by clicking the Custom/Edit Reports button.
The units used in the reports will be based on the options chosen from
VisualWeather’s Tools | Options menu item.
Formulas used for generating special reports are documented in the
appendices.
7.2 Report Parameters
Some reports require parameters to be entered by the user. Reports needing
additional information are the Wind Rose, Evapotranspiration, Crop Water
Need, GDD, GDD2, and Chill Hours. The parameters can be initially set and
then changed at any time by selecting a station on the Report Selection screen
and then clicking the Custom/Edit Reports button.
Each tab on the screen allows you to change settings for the specified report.
Enter the settings for the reports and click OK to save the settings. You can
cancel changes at any time by clicking the Cancel button.
7.2.1 Wind Rose
WIND ROSE — Select the number of Wind Speed Bins. Specify the units
(m/s, mph, km/h, or knots) for which you are entering values in the Bin
Settings for Units field, and then enter the Low and High wind speed values
13
VisualWeather™ Software
desired for each bin. Any wind speeds that fall in between the low and high
will be placed in the corresponding bin. Any value below the low value of the
first bin will be placed in the calm bin. The default values give the lows and
highs that follow the Beaufort wind scale boundaries. If you have edited the
wind rose parameters, at any time you can restore the defaults for the bins by
clicking the Restore Defaults button.
If Automatically convert values for other units is checked, the values
entered will be converted and used for the other wind speed units
automatically.
NOTE
14
The wind speed units used in reports are not those selected here.
The units used in reports will be those selected under Tools |
Options on the main screen.
VisualWeather™ Software
7.2.2 Evapotranspiration (ETo)
EVAPOTRANSPIRATION (ETO) — Select the ETo Method to be used and enter
the anemometer height in meters. The latitude, longitude, and elevation are
also used to calculate Evapotranspiration. These can be entered/changed in the
EZSetup wizard by selecting Network | Edit Weather Station from the main
menu of the Home Screen.
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VisualWeather™ Software
7.2.3 Crop Water Need
CROP WATER NEED — Select the Crop Name and enter the Planting Date.
Next enter the Duration (Days) for each crop stage (initial, development, midseason, late-season). The beginning date of each stage will be automatically
calculated. Next enter the Crop Coefficient for each stage.
NOTE
16
Alternatively, you can enter the stage start dates instead of the
duration. The duration of each crop stage will be automatically
calculated.
VisualWeather™ Software
7.2.4 Growing Degree Days and Growing Degree Days 2
GROWING DEGREE DAYS AND GROWING DEGREE DAYS 2 — Enter the Crop
Name. Next enter the Lower and Upper Temperature Limit for the crop. If
Fahrenheit is entered, the Celsius value will be calculated automatically. If
Celsius is entered, the Fahrenheit value is calculated automatically.
7.2.5 Chill Hours
CHILL HOURS — Enter the Reference (Base) Temperature in either Fahrenheit
or Celsius. The other field value will be calculated automatically.
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VisualWeather™ Software
7.2.6 Custom Reports
Custom reports are available that let you plot one or more traces on a graph
and/or monitor one or more data values in a table. To create a custom report,
press the New Custom button on the Custom/Edit Reports screen.
The Report Title and Sub Title fields are used to provide headings for the
graph. The Left and Right Axis Description fields are used to provide a label
for each axis.
The tables that are being collected to the database are listed in the Tables field.
When a table is selected from this list, the data values in that table appear in
the Fields list.
Highlight a data value from the list and click the top right-pointing arrow (or
double-click the value) to add it to the list of values to be graphed. The type of
output for the data value can be specified by clicking the cell within the Field
Type column to display a list box of output types (Max, Min, Avg, Sample, or
Other). To specify whether the value is plotted on the right or left axis of the
graph, click within the Axis cell and select Right or Left from the list box that
is displayed. A data value can be deleted from the list of values to be graphed
by right-clicking and choosing Delete. Selecting Generate daily summary
values will cause daily summary values to be shown on the graph. For
example, if a maximum air temperature is being graphed, the daily maximum
air temperature will be indicated on the graph. Selecting If time range > 2
weeks, generate and only show daily values will cause only daily values to
be graphed if the time range for the report is greater than two weeks.
Highlight a data value from the list and click the bottom right-pointing arrow
to add it to the list of values to be monitored in the table. Selecting Generate
daily values if time range >1 day will cause only daily values to be monitored
if the time range for the report is greater than one day.
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VisualWeather™ Software
7.2.7 Custom X-Y Reports
Custom X-Y report are available that allow you to plot one or more X-Y traces
on a graph and/or monitor one or more data values in a table.
The user specifies what will be used for both the X axis data values and the Y
axis data values on the graph. Each Y axis data value is plotted against the X
axis data value with an identical timestamp.
The Report Title and Sub Title fields are used to provide headings for the
graph. The Left, Right and Bottom Axis Title fields are used to provide a
label for each axis.
The tables that are being collected to the database are listed in the Tables field.
When a table is selected from this list, the data values in that table appear in
the Fields list.
Highlight a data value from the list and click the top right-pointing arrow (or
double-click the value) to add it to the list of values to be graphed. The type of
output for the data value can be specified by clicking the cell within the Field
Type column to display a list box of output types (Max, Min, Avg, Sample, or
Other). To specify whether the value is plotted on the right, left or bottom axis
of the graph, click within the Axis cell and select Right, Left or Bottom from
the list box that is displayed. There must be one and only one data value
selected for the bottom axis. Multiple data values can be selected for both the
right and left axes. A data field can be deleted from the list of values to be
graphed by right-clicking and choosing Delete.
Highlight a data value from the list and click the bottom right-pointing arrow
to add it to the list of values to be monitored in the table. The type of output for
the data value can be specified by clicking the cell within the Field Type
column to display a list box of output types (Max, Min, Avg, Sample, or
Other). A data field can be deleted from the list of values to be monitored by
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VisualWeather™ Software
right-clicking and choosing Delete. Selecting the Generate daily values if
time range > 1 day will cause only daily values to be monitored if the time
range for the report is greater than two weeks.
Press the Delete This Report button to delete this custom X-Y report.
7.2.8 Custom GDD Reports
Custom GDD report are available that are similar to the GDD and GDD2
reports, but allow the user to choose the algorithm used to calculate the GDD.
The Main Title and Sub Title fields are used to provide headings for the
report.
The method used to calculate the GDD is determined by what is selected in
GDD Method. The Cutoff Method, Temperature Fields, Lower (Base)
Temperature, and Upper Temperature Limit also affect the calculation as
explained below as they relate to each GDD Method.
•
Simple (single base temperature) – Compares mean temperature
(Tmean) to a Lower (Base) Temperature (Tbase). The Tmean value
used is based on the Temp Values to Use field. If Average Temperature
is selected, Tmean equals the Air Temp Avg Field. If Min/Max
Temperature is chosen, Tmean = (Air Temp Max Field – Air Temp Min
Field)/2. The GDD is calculated as follows:
If (Tmean > Tbase) then
GDD = (Tmean – Tbase) * dataInterval
Else
GDD = 0
20
VisualWeather™ Software
•
Upper-Lower – Uses both the Upper Temperature Limit
(upperThreshold) and Lower (Base) Temperature (lowerThreshold) to
calculate the GDD. The method of calculation changes based on both the
Temp Values to Use field and the Cutoff Method field as described
below:
o
Average Temperature
ƒ
None –
Not adjusted for upper threshold. Basically the
same as the Simple GDD Method.
ƒ
Horizontal –
If (Tmean > upperThreshold) then
Tmean = upperThreshold
ƒ
Intermediate – If (Tmean > upperThreshold) then
Tmean = Tmean – (Tmean – upperThreshold) * 2
ƒ
Vertical –
If (Tmean > upperThreshold)
then GDD = 0
The GDD is then calculated as follows:
If (Tmean > lowerThreshold) then
GDD = (Tmean – lowerThreshold) * dataInterval
Else
GDD = 0
o
Min/Max Temperature
ƒ
None –
Not adjusted for upper threshold. Basically the
same as the Simple GDD Method.
ƒ
Horizontal –
If (Tmax > upperThreshold) then
Tmax = upperThreshold
ƒ
Intermediate – If (Tmax > upperThreshold) then
Tmax = Tmax – (Tmax – upperThreshold) * 2
ƒ
Vertical –
If (Tmax > upperThreshold) then
GDD = 0
If the above calculation causes Tmax to be below Tmin, then
Tmin is set equal to Tmax.
The mean value is calculated from this new Tmax and Tmin:
Tmean = (Tmax + Tmin) / 2
The GDD is then calculated as follows:
If (Tmean > lowerThreshold) then
GDD = (Tmean – lowerThreshold) * dataInterval
Else
GDD = 0
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VisualWeather™ Software
NOTE
•
Sine – This GDD Method is an industry standard also known as the
Baskerville-Emin (BE) method. The method of calculation changes based
on the Cutoff Method field.
•
DoubleSine - This GDD Method is an industry standard. The method of
calculation changes based on the Cutoff Method field.
The Lower (Base) Temperature and Upper Temperature
Limit can be entered in either the Fahrenheit or Celsius field.
When the information is entered into one field, it will
automatically be converted to the correct units for the other field.
Press the Delete This Report button to delete this custom GDD report.
7.3 Batch Reports
Batch Reports allow you to define reports to be saved and generated at a later
time. They can be set up to run on a schedule (automatically) or on demand
(manually by the user).
To open the Batch Reports screen choose the Reports | Batch Reports menu
item from the menu on the Home screen.
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VisualWeather™ Software
7.3.1 New
To create a new batch report click the New button on the Batch Reports
Schedule screen. The Batch Report Selection screen is displayed.
This screen is much like the screen shown when manually generating a report
except you have additional fields to enter.
Batch reports can be created only for current weather stations (that is, you
cannot create Batch Reports for historical data of deleted weather stations).
Select the Output types desired. You can choose any combination of Print,
Web, .bmp, or .jpg, but you must choose at least one option. (See Section 12
for information on web output.)
Select the Report Type.
24 hour
Creates a 24 hour report. The 24 hour period covered starts at the
top of the hour and is based on the current PC time.
1 day
Creates a 24 hour report (midnight to midnight) for the last 24
hour period.
7 day
Creates a 7 day report for the last 7 days, beginning on midnight
of the first day and ending at midnight of the last day.
1 month
Creates a report for the previous month, beginning on midnight
of the first day of the month and ending at midnight on the last
day of the month.
Custom
Creates a report that starts at midnight and ends at midnight,
covering the number of days entered.
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VisualWeather™ Software
Select whether you want to generate on Demand (user initiated creation) or
according to Schedule (automatically generated).
When Generate on Demand is chosen, a defined report will be run when it is
selected from the Reports | Batch Reports menu.
When Generate According to Schedule is chosen, the report will be run
automatically based on the additional fields. The additional fields enabled will
be based on the Report Type selected as follows:
24 hour
Creates a 24 hour report. The report is created based on the
Interval and Base Date and Time. A report will be generated at
every Interval from the Base Date and Time. Each report will
cover the 24 hour period preceding the time the report is created.
1 day
Creates a 24 hour report (midnight to midnight) for the previous
day. The report will be generated daily starting at the Base Date
and Time.
7 day
Creates a 7 day report for the last 7 days, beginning on midnight
of the first day and ending at midnight of the last day. The report
is created based on the Interval and Base Date and Time. A
report will be generated at every Interval from the Base Date
and Time. Each report will cover the 7 day period preceding the
day the report is created.
1 month
Creates a report for the previous month, beginning on midnight
of the first day of the month and ending at midnight on the last
day of the month. The report will be created on the Day of
month to create Report at Time to Create Report.
Custom
Creates a report that starts at midnight and ends at midnight,
covering the number of days entered. The report is created based
on the Interval and Base Date and Time. A report will be
generated at every Interval from the Base Date and Time. Each
report will cover the n day period preceding the day the report is
created, where n is the number entered by the user.
Next Select the Reports you wish to have generated.
The units used in the reports will be based on the options chosen from
VisualWeather’s Tools | Options menu item.
After all desired settings have been selected, click the Create Batch button.
You will then be prompted for a name for the batch report. The batch report
name must be unique among all batch reports that have been created.
NOTE
24
As with creating manual reports, the Report Parameters screen
is shown if special settings for the station have not been entered
and need to be (see 7.2 Report Parameters).
VisualWeather™ Software
7.3.2 Edit
To Edit a batch report that has already been created, select it in the list and
click the Edit button. The batch report will be loaded in the Report Selection
screen. Edit the selections and click the Save Batch button. The changes will
be saved.
7.3.3 Run
All batch reports, including those set up as scheduled, can be run on demand.
Select the batch report you wish to run and click the Run button. The report
will be generated.
NOTE
Running a scheduled batch report will not affect its schedule. If
you wish to edit the schedule of a batch report, edit the batch
report and change its generation time.
7.3.4 Delete
To delete a batch report select it in the list and click the Delete button. The
batch report will be deleted.
NOTE
This action cannot be undone.
8. Station Data
To view a graphical representation of the current weather conditions for all of
the stations in your network, select the Station Data heading
Each station is displayed on its own screen. The tabs at the top of the window
can be used to navigate between screens. The data displayed must be collected
through scheduled or manual collection. VisualWeather does not actively
collect data to be displayed by Station Data.
The data displayed will be based upon the sensors that were selected when the
weather station was configured (or, for a custom station, the Data Fields
associated with the Real Time Parameters when setting up the Real Time Field
Mapping). The units used will be based on the options chosen from
VisualWeather’s Tools | Options menu item.
NOTE
The data is displayed as a project developed with Campbell
Scientific’s RTMC Pro Development software. The project file
is
VW_Multistation.rtmc2
and
is
saved
in
C:\CampbellSci\VisualWeather\RTMC. If you have RTMC Pro, you
may make changes to this project (i.e., display additional
components). Once you have made changes to the project,
VisualWeather will not modify the project. If you want to revert
to VisualWeather’s default project, you will need to delete the
project file. VisualWeather will then recreate the project the next
time Station Data is opened.
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VisualWeather™ Software
The following components are available in Station Data. Listed below each
component are the sensors (for pre-configured weather stations) and real time
fields (for custom stations) required for each condition to be displayed.
Thermometer
Air Temperature
Sensors: HMP50-ET Temp/RH Sensor, CS500, HMP35C, HMP45C, 107
Temperature Probe, or 108 Temperature Probe
Real Time Fields: Air Temperature
Wind Chill
Sensors: Sensors that measure Air Temperature and Wind Speed
Real Time Fields: (Air Temperature and Wind Speed) or Wind Chill
Note that when using Air Temperature and Wind Speed to calculate the
Wind Chill, the Air Temperature and Wind Speed must fall within these
boundaries in order for Wind Chill to be calculated:
-50 °F ≤ Air Temperature ≤ 50 °F
3 MPH ≤ Wind Speed ≤ 110 MPH
If either measurement is outside the boundaries, the Wind Chill will be
reported as N/A. The condition that caused the Wind Chill not to be
calculated will also be specified. See Appendix D for more information
on Wind Chill calculation.
Heat Index
Sensors: Sensors that measure Air Temperature and RH
Real Time Fields: (Air Temperature and RH) or Heat Index
26
VisualWeather™ Software
Note that when using Air Temperature and RH to calculate the Heat
Index, the Air Temperature and RH must fall within these boundaries in
order for Heat Index to be calculated:
Air Temperature ≥ 80 °F
RH ≥ 40%
If either measurement is outside the boundary, the Heat Index will be
reported as N/A. The condition that caused the Heat Index not to be
calculated will also be specified. See Appendix F for more information on
Heat Index calculation.
Dew Point
Sensors: Sensors that measure Air Temperature and RH
Real Time Fields: (Air Temperature and RH) or Dew Point
See Appendix C for information on Dew Point calculation.
Compass
Wind Direction
Sensors: 034B, GilSonic, 034A MetOne, 03001 Wind Sentry, 05103
R.M. Young Wind Monitor, or 05350 R.M. Young Wind Monitor
Real Time Fields: Wind Direction
Wind Speed
Sensors: 034B or GilSonic
Real Time Fields: Wind Speed
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VisualWeather™ Software
Rain Last 24 Hours
Rain Last 24 Hours
Sensors: TE525-T Tipping Bucket Rain Gage, TE525WS Tipping Bucket
Rain Gage, TE525mm Tipping Bucket Rain Gage, or CS700 Tipping
Bucket Rain Gage w/syphon
Real Time Fields: Rain Fall
Relative Humidity
Relative Humidity
Sensors: HMP50-ET Temp/RH Sensor, HMP35C, or HPM45C
Real Time Fields: Relative Humidity
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VisualWeather™ Software
Barometric Pressure
Barometric Pressure
Sensors: CS105MD
Real Time Fields: Barometric Pressure
Solar Radiation
Solar Radiation
Sensors: CS305-ET Solar Radiation or LI200X
Real Time Fields: Solar Radiation
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VisualWeather™ Software
Air Temperature and Relative Humidity
Air Temperature and Relative Humidity
Sensors: Sensors that measure Air Temperature and Relative Humidity
Report Fields: Air Temp Avg and RH Avg (backfills last 7 days)
Soil Temperature and Soil Water Content
Soil Temperature
Sensors: 107 Temperature Probe or 108 Temperature Probe
Real Time Fields: Soil Temperature
Soil Water Content
Sensors: CS615 or CS616
Real Time Fields: Soil Water Content
Battery Voltage
Datalogger Battery Voltage
Real Time Fields: Batt Voltage
30
VisualWeather™ Software
Enclosure RH
Enclosure RH (inside the weather station enclosure)
Real Time Fields: Enclosure RH
9. Monitoring the Data Collection Status
To view the current status of scheduled collection for stations, select the
Collection Status heading or Network | Collection Status menu item from the
main menu of the Home screen.
The Collection Status screen shows the current status of all stations currently
configured in VisualWeather. An exclamation icon is shown by all stations
with which VisualWeather is currently having trouble communicating. The
columns shown are described as follows:
Avg Err % - A running average of the number of communication failures and
retries over a period of time.
Coll State - This column provides information on the mode of data collection
that the device is in.
Normal - Data is being collected on schedule.
Primary - Data collection will be attempted on the primary retry schedule
because of failures of normal data collection.
Secondary - Data collection will be attempted on the secondary retry
schedule because of failures of the primary retry schedule.
Schedule Off - The data collection schedule has been toggled off.
Comm Disabled - Communication has been disabled, by the user or by
VisualWeather, for the device, a parent device, or the entire network.
Invalid Table Defs - Data collection has been disabled by VisualWeather
because the table definitions do not match what VisualWeather expects.
Go to the EZSetup Wizard and refresh the table definitions by selecting
Update Table Definitions from the Data Files | Mapping screen.
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VisualWeather™ Software
Network Paused - VisualWeather has paused communication in the
network.
Unreachable - The device cannot be reached through the network.
Comm Status - A device has four communication states: Normal, Marginal,
Critical, or Unknown. The current status of the device will be reflected in this
column.
Line State - The state of communication with the device in the network.
Off-line - No communication is taking place with the device.
On-line - Communication for all parent devices for the device has been
successful and the parent devices have been put into a transparent state.
Therefore, an On-Line state for a device indicates that the communication
link is ready for the device, but it may not necessarily be on-line yet.
Transparent - The device is part of an active communication link. For
instance, when a datalogger is called using a phone modem, the phone
modem will become transparent once communication is established with
the datalogger.
Comm Disabled - Communication has been disabled either by the user or
by VisualWeather.
Hanging Up - VisualWeather is in the process of shutting down
communication with the device.
Vals Last Coll - The number of values that were collected during the last data
collection attempt.
Vals to Coll - The number of values that were available for collection during
the last data collection.
Last Col Attempt - The date and time that data collection was last attempted
with the datalogger.
Last Data Collection - The date and time of the last successful data collection
with the datalogger.
Next Data Coll - The date and time of the next scheduled data collection for
the device.
Total Attempts - The total number of times VisualWeather has attempted to
communicate with the device.
Total Failures - The total number of times the primary and secondary retries
for a device have been exhausted before the communication attempt was
successful.
Total Retries - The total number of times VisualWeather has attempted to
communicate with a device after the original attempt failed.
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VisualWeather™ Software
NOTE
Total Retries and Total Failures will equal Total Attempts.
A graph is shown for each station to help show historical communication
information about the station. A maximum of 72 bars are shown. Each bar
represents 15 minutes. The communication failure percentage determines the
height of the bar. It is calculated as: (Failures + Retries) / Attempts. The color
of each bar is determined by the following rules:
Green: No Retries, No Failures
Blue: Retries, No Failures
Red: Failures
Gray: No Attempts
Scheduled collection can be paused for all stations in the network by checking
the Pause Scheduled Data Collection for all Stations checkbox.
10. Weather Station Network
To view all the stations that are currently configured in VisualWeather, select
the Weather Station Network heading or Network | Weather Station Network
menu item from the main menu of the Home screen.
The Weather Station Network screen shows all weather stations currently in
the network. Station information is displayed for the station that is currently
selected.
To add a new station to the network, click the New Station button. The
EZSetup Wizard as described in Section 5.1 is opened.
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VisualWeather™ Software
To remove a station from the network, select it and click the Remove Station
button. The station will become a past weather station. Reports may still be
generated for the station with historical data, but no new data can be collected
from the station. A station may be removed from the network completely from
the Network | Remove Station menu item.
NOTE
The Remove action cannot be undone.
To edit the configuration for a weather station, select it and click the Edit
Station button. The EZSetup Wizard as described in section 5.1 is opened.
To quickly move to a specific section of the Wizard, select it from the Progress
panel on the left size of the Wizard.
11. Data Mapping
Data mapping is required to associate measurements and final storage data in a
custom weather station with the values required for report generation and
monitoring of current conditions and status.
11.1 Report Field Mapping
Data mapping required for report generation is done from the Report Field
Mapping screen of the EZSetup Wizard. (Report Field Mapping is the second
screen under the Data Files/Mapping section of the EZSetup Wizard.)
Each required Report Parameter needs to be associated with a value, or Data
Field, in the datalogger.
To map a value, first select the data table or array ID that contains the value
you want to associate from the Tables list. When a table or array is selected,
the values in that table or array are displayed in the Fields list. Click the Data
Field cell for which you want to map a value, and then highlight a data value
from the Fields list and click the right-pointing arrow (or double-click the
value). The name of the field will be displayed in the Data Field when it has
been mapped. To clear an association, right click and select Clear. The Field
Units field should specify the units of the data value from the datalogger. This
will be converted as needed for purposes of the reports. If the default unit is
incorrect, click within the field to enable a list box from which to select an
appropriate unit.
Report parameters required for report generation are shown below. Unless
noted otherwise, all listed parameters are required for the specified report. All
parameters used for any one report must have the same interval.
Battery Voltage
•
•
Battery Voltage Min (required)
Battery Voltage Max (optional)
Enclosure Relative Humidity
•
34
Enclosure RH Max
VisualWeather™ Software
Air Temperature (requires one of the following)
•
•
•
Air Temperature Min
Air Temperature Max
Air Temperature Avg
Solar Radiation
•
Solar Radiation Avg
Relative Humidity (requires one of the following)
•
•
•
RH Min
RH Max
RH Avg
Rain
•
Rain Fall Total
Wind Speed
•
Wind Speed Max
Wind Rose
•
•
Wind Speed Avg
Wind Direction Avg
Barometric Pressure (requires one of the following)
•
•
BP Min
BP Max
Leaf Wetness
•
•
•
•
Leaf Wet AVg
Minutes Wet
Leaf Transition Point
Leaf Wetness Temperature
Snow Depth
•
•
Snow Depth Avg (required)
Snow Sensor Height (optional)
Auxiliary Temperature (requires one of the following)
•
•
•
Aux Temperature Min
Aux Temperature Max
Aux Temperature Avg
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Soil Water
•
Soil Water Avg
Fuel Moisture
•
Fuel Moisture Avg
Evapotranspiration
•
•
•
•
Air Temperature Avg
RH Avg
Wind Speed Avg
Solar Radiation Avg
Crop Water
•
•
•
•
Air Temperature Avg
RH Avg
Wind Speed Avg
Solar Radiation Avg
GDD
•
Air Temperature Avg
GDD2
•
Air Temperature Avg
Chill Hours
•
Air Temperature Avg
Dew Point (requires one of the following)
•
•
Dew Point Min
Dew Point Max
Wind Chill (requires one of the following)
•
•
Wind Chill Min
Wind Chill Max
Heat Index (requires one of the following)
•
•
36
Heat Index Min
Heat Index Max
VisualWeather™ Software
11.2 Real Time Field Mapping
Data mapping required to monitor Current Conditions and view Station Data is
done from the Real Time Field Mapping screen of the EZSetup Wizard. (Real
Time Field Mapping is the fourth screen under the Data Files/Mapping section
of the EZSetup Wizard.)
The goal is to associate the RealTime Parameter with a value, or Data Field,
in the datalogger. To map a value, first select the data table (typically Public or
Inlocs) that contains the value you want to associate from the Tables list.
When a table is selected, the values in that table are displayed in the Fields list.
Click the Data Field cell for which you want to map a value, and then doubleclick the value to be mapped in the Fields list. The name of the field will be
displayed in the Data Field when it has been mapped. To clear an association,
right click and select Clear. The Units field should specify the units of the data
value from the datalogger. This will be converted as needed for display
purposes. If the default unit is incorrect, click within the field to enable a list
box from which to select an appropriate unit.
12. Web Output
Web output can be enabled From VisualWeather’s main menu, by selecting
Tools | Web Output Options.
When Web Output Enabled is selected, the following will occur:
•
Station Data launched from the VisualWeather main screen will output
images when new data is available. If Station Data Screens is selected,
each screen will be output as Local Output Folder\<station name>.png.
If Individual Station Data Components is selected, individual data
controls will be output as Local Output Folder\<station
name>.<componentname>.png
•
When Web is checked in the Output As field for a batch report, all
reports for the batch will be saved to Local Output Folder\<station
name>. They are saved as both paginated jpg images and as .html pages
•
A webdata.xml file is stored in the Local Output Folder. This file
contains the list of stations and for each station: the last data values
collected and references to batch reports configured to be output to the
web. This file is updated when data is collected, and when a batch report
is generated.
•
Default.htm is located in the web folder. Default.htm uses WebData.xml
and constructs a web site that allows the user to see the stations, station
data, and batch reports generated for the web.
•
When the Include Station In Web Report Image Paths option is
checked, the image path referenced in each web report is <station
name>/<image name>. When creating your own website or loading the
reports directly into a browser (without using the shipped default.html),
you may wish to uncheck this option. With the option unchecked, the web
report image path will be just be the image name without the relative path
(station name) included. The default for this option is checked.
37
VisualWeather™ Software
•
NOTE
If FTP Enabled is checked, all files that are being output to the Local
Output Folder will also be sent to the Remote Folder using the specified
FTP settings. These files include station data images, WebData.xml, and
batch reports.
In order to set up the web page, the user will initially need to
copy default.htm and the <working directory>\Web\yui
directory to the FTP location. These will not be copied
automatically.
Host Address
The FTP server to which the files will be sent.
User ID
The username on the FTP server.
Password
The user’s password on the FTP server
SFTP (SSH FTP)
Select the check box to enable SFTP (SSH File Transfer Protocol).
Clear the check box to disable SFTP.
Four server types are supported. Three of these are supported by
default: FTP (File Transfer Protocol), FTPS (FTP over implicit
TLS/SSL), and FTPES (FTP over explicit TLS/SSL). The fourth
type, SFTP, is only enabled if this check box is selected.
Remote Folder
Selects the folder on the FTP server to which the files will be
transferred. The files will be saved to this folder under the FTP
server’s FTP root directory. Press the button to browse to the desired
directory.
38
VisualWeather™ Software
13. Exporting and Importing Data
13.1 Exporting Data
Data retrieved from a weather station can be exported to a file for further data
processing. From VisualWeather’s main menu, select Tools | Export Data.
Highlight the desired weather station name from the list of Current or Past
Weather Stations. The names of the data tables associated with the selected
weather station will be displayed.
Select the desired table to be exported in the Select a Data Table list. Next
select the range of data to be exported using the Starting at and Ending at
fields.
By default, exported data will be saved in the <working directory>\Export
folder with a name of <station name>.dat (the working directory is the
directory specified in the install and station name is the name of the weather
station). A different directory can be selected by clicking the Browse button.
Click the Export button to begin exporting the data.
Data is exported in Campbell Scientific’s TOACI1 format (an ASCII commaseparated format with headings). The exported data can be imported into a
spreadsheet or other software for further data processing.
39
VisualWeather™ Software
13.2 Importing Data
The Import Data function can be used to import data from a data file into
VisualWeather’s database for a specified weather station. From
VisualWeather’s main menu, select Tools | Import Data.
Type in the filename to be imported in the Data File field or press the browse
(…) button to browse to the desired file. If the data file is from an array-based
logger, you will also need to specify an associated *.FSL file (file storage label
file) in the FSL File field and then choose the array to import from the dropdown menu in the Array field. (The FSL File field and Array field will be
disabled for data files from table-based loggers.)
To specify where the data should be imported, choose a Station and Table
from the drop-down lists.
VisualWeather will attempt to determine which database field corresponds to
each field in the imported data file. This will be displayed in the table on the
bottom half of the screen. Changes can be made by clicking on any cell under
DataBase Field and choosing a different value from the drop-down menu. If
no DataBase Field is specified, the corresponding Field from File will not be
imported into the database.
Once all of the required information has been entered, press the Import button
to begin the process.
14. Backup/Restore Network
The entire weather station network can be backed up to a file. The network
can then be restored, if necessary. The backup includes the network, the data
for each station, and *.ini files which contain the settings for each station.
NOTE
WebData.xml is the only file from the <working
directory>\Web folder that is part of the backup. Batch reports
and/or real time images will need to be backed up by the user if
desired.
To create a backup or restore a network, select Network | Backup/Restore
Network from VisualWeather’s main menu.
By default the backup is saved to
C:\Campbellsci\VisualWeather\VisualWeather.bkp. A different folder and/or
filename can be specified by pressing the button to display a window from
which to choose the folder and filename. After selecting the folder and
filename, press the Backup button to create the backup file.
To restore a backed-up network, choose the desired Backup File and then
press the Restore button.
NOTE
40
Beginning with VisualWeather 3.0, a restore cannot be
performed from a backup file created using a version of
VisualWeather prior to version 3.0.
VisualWeather™ Software
15. Programming Custom Weather Stations
When an ET106, ET107, Toro T107, or MetData1 station is configured in
VisualWeather, a program for that weather station is automatically generated
based on the sensors chosen during setup.
When custom stations are configured in VisualWeather, you must generate the
program yourself if the station has not been previously programmed. Short Cut
for Windows (SCWIN) has been included in VisualWeather for this purpose.
SCWIN has a wizard-like interface that steps you through programming a
datalogger to measure your sensors and to select the data to be stored in the
datalogger's memory. Once a program is completed, SCWIN generates a
wiring diagram that aids in connecting your sensors to the datalogger.
SCWIN can be opened from VisualWeather’s Tools | ShortCut menu option.
Complete information on using SCWIN is included in its on-line help.
16. Advanced Features
16.1 Run On Startup
VisualWeather can be set to open and begin collecting data from the weather
stations when your computer is started. From the File menu, select Run On
Startup. When a check mark appears to the left of the item, it is enabled. The
menu item is a toggle. When the check mark is absent, select the menu item to
enable the option. When the check mark is present, select them menu item to
disable the option.
16.2 LogTool
VisualWeather includes a LogTool utility that is used to view the
communication logs that are generated when communicating with the weather
stations. This tool can be opened from Tools | LogTool.
If you are experiencing difficulty connecting with a weather station, a
Campbell Scientific applications engineer may ask you to open this utility and
provide information from the logs to help troubleshoot the problem. There are
four logs, each of which are explained briefly, below.
16.2.1 Log Types
Transaction Log (tran$.log) - This log includes information on the
transactions that occur between VisualWeather and devices in the weather
station network. Examples of these types of events are clock checks/sets,
program downloads, and data collection.
Communication Log (comms$.log) - This log records information on the
quality of communications in the weather station network. Three types of
messages are recorded: status messages, warning messages, and fault
messages.
41
VisualWeather™ Software
Object State Log (state$.log) - This log is used for troubleshooting an object
in the weather station network. The information in this log conveys the state of
an object at a given time.
Low Level I/O Log (io$SerialPort_1) - This log displays low level incoming
and outgoing communications for a root device (i.e., serial port).
16.2.2 Using LogTool
When the LogTool is first opened, two logs are displayed: the transaction log
and the communication log. The Object State log and the Low Level I/O log
can be displayed by toggling their associated button on the toolbar.
Parsing Options - Toggles the display of the message parsing window.
Toolbars - Toggles the display of an individual tool bar for each of the logs.
You can pause the display of messages for a tool bar by selecting the Pause
check box. You can clear all messages for a log by pressing the Clear
Messages button.
Trans Log, Object State Log, Comms Log - Toggles the display of the
associated Log.
I/O Log - Opens the Low Level I/O log for a specific COM port in a new
window.
TimeStamp Options - Allows you to select the format for the time stamp in
the logs. If none of the options are enabled (an option is enabled if a check
mark appears to the left of the option name), only the time is displayed
(hh:mm:ss AM/PM). If Date is selected, a date (MM/DD/YY) will be added to
the time stamp. If Military is selected, the time stamp will be displayed in 24
hour format instead of 12 hour format. If ms Resolution is chosen, the time
stamp will also include milliseconds.
16.2.3 Saving Logs to File
The log messages currently being displayed on the LogTool screen can be
manually saved to a text file by selecting File | Save Log Windows to File. In
addition, these logs can be printed by selecting File | Print Log Windows.
42
VisualWeather™ Software
Log files can be saved to individual files automatically by selecting Options |
Log File Settings from the LogTool menu and selecting To Disk for the
appropriate log. In addition to controlling whether the logs are saved to files,
Log File Settings also lets you set the size and number of log files that are
created. One set of log files each is created for the Transaction,
Communication, and Object State logs. For the Low Level I/O logs, one set of
logs will be created for each of the root level devices in the network. Once the
maximum number of logs have been created (set by the File Count) the next
log file created will overwrite the oldest file.
The following settings are used to save the logs to disk as well as to control the
number and size of the log files.
To Disk – Selecting this check box enables saving the associated logs to files
on the server computer hard disk.
File Count – This setting determines the number of log files to be saved to
disk for this type of log. The server will store up to the number specified
before overwriting the oldest log.
File Size – This setting determines how big the log file is allowed to grow
before being saved to an archived file. The $ sign identifies the active file.
Once a file reaches the specified File Size, it is saved to disk with a sequential
number beginning with 0 (e.g. tran0.log, tran1.log, tran2.log…).
43
VisualWeather™ Software
44
Appendix A. Evapotranspiration, Vapor
Pressure Deficit, and Crop Water Needs
A.1 Evapotranspiration
This appendix explains the process of evapotranspiration (ET) and the methods
VisualWeather uses to calculate hourly ET values. It also explains the
calculations for vapor pressure deficit of the air and crop irrigation based on
ET.
Evapotranspiration is the process of water loss in vapor form from a unit
surface of land both directly (evaporation) and from leaf surfaces
(transpiration).
The energy required for vaporization comes mainly from the solar radiation
and the ambient air temperature. Higher values of solar radiation and ambient
air temperature increase ET. As the air near the soil surface saturates with
water vapor, the rate of water loss due to evaporation decreases. Therefore,
with increasing humidity ET decreases. The wind displaces saturated air with
relatively drier air. Thus, at higher wind speeds ET increases. Other factors,
such as soil composition, irrigation frequency, rain, and crop type also play
important roles that affect the process.
Given the diversity of crops, their heights, ability to absorb solar radiation,
foliage resistance to wind, and variability in wind speeds at various altitudes
some standards have to be predefined as a basis for comparisons of ET under
variable climatic conditions.
For the purpose of standardization the following definition has been adopted[1]
for a reference crop surface.
'A hypothetical reference crop with an assumed crop height of 0.12
meters, fixed surface resistance of 70 S/m and an albedo of 0.23'.
This hypothetical reference crop surface closely resembles an adequately
watered, extensive surface of green grass of uniform height, completely
shading the ground.
The (bulk) surface resistance, rs, consists of resistance to vapor flow through
the soil surface and crop leaves. The latter is called stomatal resistance.
Stomata are small openings on leaves through which the vapor is lost. For the
reference crop the value of rs is fixed at 70 S/m.
Albedo is a crop's ability to reflect the incident radiation. Also known as
canopy reflection coefficient, its value for the reference crop is 0.23 (unitless
number). Reference crop surface albedo = (radiation energy reflected by
reference crop surface) / (solar radiation incident on the reference crop surface)
= 0.23.
A-1
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
Over the years the Food and Agriculture Organization of the United Nations
(FAO) has published several documents related to evapotranspiration and other
agriculture related issues. We allow the option of switching between three ETo
methods:
1.
Standardized Reference ETo for Short Crops (~0.12 meter in height),
Grass Reference
2.
Standardized Reference ETo for Tall Crops (~0.50 meter in height),
Alfalfa Reference
3.
FAO56 Penman-Monteith Method for Estimation of ETo
The only difference between these methods are the values used for Cn, and Cd
in the ETo equation. These values are described in section 7 below.
The ETo equation is as follows:
ETo =
where,
0.408 Δ (R n - G) + γ (C n /(T + 273)) u 2 (e s - e a )
Δ + γ (1 + C d u 2 )
(1)
ETo = reference evapotranspiration (mm/day);
Δ = slope of the vapor pressure versus temperature curve (kPa/°C)
Rn = net radiation at the crop surface (MJ/m²/hour)
G = soil heat flux density (MJ/m²/hour)
γ = psychrometric constant (kPa/°C)
T = air temperature at 2 m height (°C)
u2 = avg wind speed at 2 m height (m/s)
es = saturation vapor pressure (kPa)
ea = actual vapor pressure (kPa)
es - ea = saturation vapor pressure deficit (kPa)
calculating ETo:
Because the main climatic factors which determine ET values (solar radiation,
temperature, relative humidity, and wind speed) vary throughout the day,
VisualWeather uses hourly average data values rather than their daily averages
in calculating ETo
Equations used to calculate the value of each variable in equation (1), related
quantities, their units, etc., are presented below.
NOTE
Please refer to Table 1 at the end of this Appendix for listings of
all quantities and their symbols and units used in the ETo
calculations)
1.
Calculations for Δ[2, 3] (slope of the vapor pressure curve).
Δ=
4098[0.6108 e (17.27T)/(T+237.3) ]
T is temperature in °C.
A-2
(T + 237.3) 2
(2)
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
2.
Calculations for Rn (net radiation at the crop surface).
The net radiation, Rn, is the algebraic sum of radiation at the crop's
surface, with the sign convention that the incoming radiation is positive
and the outgoing radiation is negative. The incoming radiation is higher in
energy (i.e., shorter in wavelength) than the outgoing radiation (which is
longer in wavelength). The net radiation at the crop's reference surface is:
Rn = Rns − Rnl
where:
Rns = Shortwave Radiation = 0.77Rs
Rnl = Longwave Radiation
In the daytime incoming net radiation > outgoing net radiation, Rns > Rnl,
therefore Rn is positive.
In the nighttime incoming net radiation < outgoing net radiation, Rns <
Rnl, therefore Rn is negative.
The overall value of Rn is positive over a 24-hour period.
2a. Calculations for Rnl (long wave radiation at the crop surface).
The amount of energy radiated back into the atmosphere is proportional to
the fourth power of the absolute temperature of a radiating surface (Rnl
αT4). This is known as Stefan-Boltzmann's law, in context with black
body radiation. The proportionality constant for this relation is known as
Stefan-Boltzmann constant, σ.
The value of the Stefan-Boltzmann constant is:
4.903x 10-9 MJ m-2 K -4 day -1 = 4.903x 10-9 x 106
(1 day x 24 hours / day x 3600 sec / hour)
= 5.675 x 10 -8 W m-2 K-4
σ=
However, the radiation emitted into the atmosphere gets absorbed by
clouds, vapors, dust and gases like CO2. Thus the magnitude of Rnl would
be less than that predicted by the Stefan-Boltzmann law. Therefore, in
calculating Rnl, the Stefan-Boltzmann law has to be corrected by
considering factors such as humidity and clouds and assuming that
concentrations of other absorbers remain constant. The following
equation is used to calculate the long wave Rnl.
Rnl = σ Thr 4 (0.34 - 0.14 (e a)1/2 ) (1.35 (RS / RSO) - 0.35)
(3)
where, Rnl = net outgoing longwave radiation (MJ m-2 hour -1)
σ = 2.043 x 10 -10 (MJ m-2 K-4 hour -1)
ea = actual vapor pressure (kPa)
RS= measured solar radiation (MJ m-2 hour -1)
RSO = calculated value of clear-sky solar radiation (MJ m-2 hour-1)
RS/RSO = relative value of short wave radiation, 0.2 <RS/RSO <=
0.8 (no units)
Thr = hourly average temperature in Kelvin
A-3
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
2b. Calculation of the Radiation Ratio (Rs/Rso)
Rs = measured value of solar radiation (MJ/m2 /hour)
Rso = clear sky solar radiation; i.e., solar radiation with no cloud cover
(MJ/m2 /hour)
The general equation used to calculate the solar radiation is:
Rs = (as + bs (n/N))Ra
(4)
where
as = constant = 0.25
bs= constant= 0.50
n = actual sunshine hours on a given day
N = expected sunshine hours on a given day
Ra= extraterrestrial radiation
If the day is entirely clear then n = N and
Rs = (as + bs )Ra = (0.25 + 0.50)Ra ˜ 0.75Ra = Rso.
If the day is entirely cloudy, then n = 0 and Rs = (as )Ra ˜ 0.25 Ra.
Therefore the ratio, Rs/Rso on a completely cloudy day would be:
Rs/Rso ˜ 0.25 Ra/0.75 Ra ˜ 0.33 about 0.3.
Therefore, 0.3 < Rs/Rso < 1.0 define limits of the ratio.
In the nighttime
Rs = 0 at nighttime. However, Rs/Rso should not be taken to be 0 or 0.3,
since the sky may be cloud free. For the nighttime the radiation ratio 2 to
3 hours before sunset is used. To identify this radiation ratio 2 to 3 hours
before sunset, the following algorithm is used:
When the solar time angle (ω), satisfies the following condition, the
radiation ratio is saved and used throughout the night:
(ωs - 0.79) <= ω <= (ωs - 0.52)
where ωs is the sunset hour angle (in radians). ωs is calculated as follows:
ωs = π/2 - arctan[ tan(φ)tan(δ) / X 0.5]
(5)
where X = 1 -[ tan(φ)]2[tan(δ)]2 and X = 0.00001 if X <= 0
2c. Calculations for RSO (clear sky radiation).
Measured values of solar radiation, RS , are actually extraterrestrial
radiation (Ra) reaching the earth corrected by daily conditions; i.e.,
whether a particular day is clear or overcast. The following equation
shows this relation:
RS= (aS + bS (n/N)) Ra
A-4
(6)
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
Where n = number of hours of actual sunshine (hours)
N =maximum possible number of hours of expected sunshine
(hours)
For a completely overcast day n = 0; therefore,
RS= aS Ra, the constant aS = fraction of extraterrestrial radiation reaching
the earth on a overcast day.
For an entirely clear day n = N
RS= (aS + bS )Ra = clear sky radiation , aS + bS = fraction of extraterrestrial
radiation reaching the earth on a clear day. Thus,
RS = (aS + bS )Ra = RSO
(7)
When calibrated values of aS and bS are not available,
RSO = (0.75 + 2 x 10 -5 z )Ra
(8)
Where: z= station elevation in meters
2d. Calculations for Ra (extraterrestrial radiation).
The extraterrestrial radiation, Ra, can be calculated as follows:
Ra =
12 (60)
G Sc dr[(ω 2 - ω1)sin( φ)sin(δ ) + cos( φ)cos(δ )(sin(ω 2) - sin(ω1))]
π
(9)
GSc = Solar constant = 0.0820 MJ m-2 Min -1 =1.36 x 10 3 W/m 2 = 1.36 k
W/m 2
dr = inverse relative distance Earth-Sun =
1 + 0.033 cos ( (2 π /365) J ) , J is day of the year
(10)
δ = solar declination (radians) =
0.409 sin ((2 π/365) J - 1.39)
(11)
φ = latitude of the location (radians ) = ( π/180) x latitude in degrees
ω1 = solar time angle at the beginning of period (radians) =
ω - π t1/24 = ω - π /24 for hourly step
(12)
ω2 = solar time angle at the end of period (radians) = ω + π t1/24 = ω + π
/24 for hourly step, since t1 = 1
ω = solar time angle at midpoint of the period =
( π/12) [ (time + 0.06667( Lz - Lm ) + S c) -12]
(13)
time = standard (military) clock time at the midpoint of the period
(hours); e.g., t =14.5 hours between 1400 and 1500 hours.
A-5
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
Lz = Longitude of the center of the station's time zone (west of the
Greenwich line as 0o ) around the earth in clockwise direction (degrees
west of Greenwich)
Lm = Longitude of the measurement site (west of the Greenwich line as
0 o)
3.
Sc = seasonal correction for the solar time (hour) =
0.1645 sin (2b) -0.1255 cos(b) -0.025 sin(b)
(14)
b = 2π (J-81)/364 where J is day of the year between
1 (January 1) and 365 or 366 (December 31)
(15)
Calculation of G (soil heat flux).
The equation to calculate soil heat flux changes depending upon the ETO
method used, and whether it is night or day. The following table describes the
equation to use for each method and daytime/nighttime.
Nighttime:
Standardized Short Grass
0.1Rn
Standardized Tall Grass
0.4Rn
FAO56
0.1Rn
Daytime:
4.
Standardized Short Grass
0.5Rn
Standardized Tall Grass
0.5Rn
FAO56
0.2Rn
Calculation of γ (psychrometric constant).
γ = cP P/ελ
(16)
where, cP = specific heat capacity at constant pressure = 1.013 x 10-3
MJ/kg/°C)
ε = ratio of molecular weight of water to molecular weight of dry
air = 0.622
λ = latent heat of vaporization of water = 2.45 MJ/kg
P = atmospheric pressure (kPa)
Substituting values of constants, γ becomes
γ = 0.000665 P
A-6
(17)
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
where the atmospheric pressure is obtained from the following equation:
⎡ 293 - 0.0065Z ⎤
P = 101.3 ⎢
⎥
293
⎣
⎦
5.26
(18)
where, Z = Elevation in meters. In the above calculation the temperature
is assumed to be 20°C; hence,
T (Kelvin) = T (°C) + 273 =293. Note that by taking the value of
temperature to be 20 °C at all altitudes the temperature dependence of γ
has been ignored.
At sea level Z= 0; therefore, P = 101.3 kPa. At a higher altitude the
pressure P drops below this value, since the air is less dense. As the
altitude increases, P decreases and so does γ.
VisualWeather computes the atmospheric pressure, P, based on the userentered elevation.
Note that the latent heat of vaporization of water, λ is also a function of
temperature. However, its variation with temperature is small enough to
be neglected. For the FAO 56 PM equation the value of λ is assumed to
be constant, λ = 2.45 MJ/kg.
5.
Calculation of e°(Thr) (saturation vapor pressure at air temperature
Thr).
The saturation vapor pressure is related to air temperature, T
e°(Thr) = 0.6108 e (17.27T) / (T + 237.3)
(19)
Note that the right-hand side of this equation forms a part of the
numerator in equation (3) above.
6.
Calculation of ea (average hourly actual vapor pressure).
ea = e°(Thr)*RHhr/100
(20)
RHhr is the average hourly relative humidity (%)
Finally these individual results are combined to calculate hourly values of
ETo by using equation (2).
Denominator = Δ + γ (1 + 0.34 u2 )
First term = 0.408 Δ (Rn-G) / (Δ + γ (1 + 0.34 u2 ))
Second term = γ (37/(Thr + 273)) u2 (e°(Thr)-ea)) / (Δ + γ (1 + 0.34 u2 ))
ETo (mm/hour) = First term + Second term
A-7
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
The 24 hourly values of ETo calculated using equation (2) are added to
derive an ETo (mm/day) value for a day. This process is repeated 7 times
for weekly reports and 30 times for a monthly report.
7.
Cn, Cd constants
The value of Cn and Cd are dependent upon the ETo method used and
whether it is day or night. The following table shows the values used for
each method and time of day.
Method
Day
Night
ETO Short
Cn = 37, Cd = 0.24
Cn = 37, Cd = 0.96
ETO Tall
Cn = 66, Cd = 0.25
Cn = 66, Cd = 1.7
FAO56
Cn = 37, Cd = 0.34
Cn = 37, Cd = 0.34
Additional Notes:
1.
VisualWeather accesses hourly average values of temperature (T,
°C), relative humidity (RH, fraction), wind speed (u, m/s), and total
hourly solar radiation (Rs, W/m2) from the database.
2.
Solar radiation values are stored in W/m2 but these are multiplied by
a factor of 0.0036 to convert them into MJ/m2/hour.
3.
Wind speed varies with altitude. Anemometers are either 2 or 3
meters for agronomy, and 10 m above the ground level if the
application is in meteorology. The ETO equation requires that wind
speeds be specified at a standard height of 2 meters. The following
equation is applied to determine wind speed at 2 m height, regardless
of the anemometer position above the ground level.
u2 = u*
(4.87)
D
(21)
Where, u2= wind speed at standard 2 meter height
D = ln (67.8*Ht -5.42)
Ht= Height is the height of anemometer above the ground level
(meters)
If Ht = 2 meters then u2 = u
A.2 Vapor Pressure Deficit of the Air
The vapor pressure deficit (kPa) of the air is the difference between the value
of saturated vapor pressure (maximum vapor it can accommodate at a given
temperature without condensation) and the actual vapor pressure (the amount
of vapor it holds at the time).
A-8
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
This difference is calculated by calculating the saturated vapor pressure of the
air
VP deficit = (e°(Thr)-ea))
Where,
e°(T) saturated vapor pressure (kPa) of the air at temperature T
(Ref. Equation (19) above)
ea
actual vapor pressure (kPa) of the air
(Ref. Equation (20) above)
A.3 Crop Water Needs, Crop Coefficients
A crop's life cycle consists of four stages, initial period, development stage,
mid-season stage, and the late-season stage.
•
The initial stage is the length of time (days) between the planting date and
the date at which approximately 10% of the ground surface is covered
with green vegetation.
•
The development stage is the number of days between the 10% ground
cover to nearly full ground cover. The full ground cover often coincides
with flowering.
•
The mid-season starts at full ground cover and ends when a crop shows
signs of maturity, e.g. yellowing of leaves.
•
The late season lasts between crop's maturity to its harvest.
During each stage a crop's water need will vary. This requires adjusting the
amount of water supply to the crop.
The amount of water (in mm/day or inches per day) needed by a crop is
calculated by multiplying the reference crop evaporation (ETo) described
earlier by the crop coefficient (Kc) applicable to that crop in a given stage of
its growth.
ETc = ETo x Kc
(22)
These topics, along with useful data applicable to several crops can be
obtained by accessing the following web site:
http://www.fao.org/docrep/X0490E/x0490e00.htm#Contents
Information available at this web site should serve only as a guide. It is the
responsibility of users to provide the correct value of Kc applicable to their
situation. Contacting local agricultural agencies may provide information
about crops grown in that region.
A-9
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
Table 1. Names, symbols and units of all quantities used in calculations of hourly ETo values.
Symbol
Unit
Mean hourly temperature
Ta
o
Mean hourly RH
RH
percent
Mean hourly wind speed at 2 meter height
u2
m/sec
Total hourly solar radiation
Rs
MJ/m2/hour
Z
meters
Meteorological Data
C
Data Related to Station's Location
Elevation
Weather station's longitude
Always west of Greenwich line
(with Greenwich line as 0 degrees)
(user-entered)
Lm
degrees
minutes
seconds
Weather station's latitude
(user-entered)
phi
degrees
minutes
seconds
North or south of the Equator
(user-entered)
N or S
No Units
Lz
degrees
Ht
meters
Day of the year
J or DOY
integer
Begin time hour (military time, hour; e.g., 1400)
tBegin
hour
End time hour (military time, hour; e.g., 1500)
tEnd
hour
Standard (military) time at step's midpoint (e.g.; 14.5)
time
hour
Slope of the vapor pressure curve
Δ
kPa/oC
Specific heat capacity at constant pressure
Cp=0.001103
MJ/kg/oC
Ratio of mol weights of water to dry air
ε=0.622
no units
Standard meridian (midpoint of the time zone)
Anemometer position above the ground level
(user-entered)
Data Related to Time
Calculated Values
A-10
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
Latent heat of vaporization of water
λ=2.45
MJ/kg
Atmospheric pressure
P
kPa
Psychrometric constant
γ
kPa/oC
Saturation vapor pressure at T
eo(T)
kPa
Actual vapor pressure
ea
kPa
Vapor pressure deficit of the air at T
eo(T)-ea
kPa
Solar constant
GSc= 0.082
MJ/m2/min
Constant used in seasonal correction
b
radians
sin (b)
cos(b)
sin(2b)
none
none
none
Seasonal correction
Sc
hour
Inverse relative sun-earth distance
dr
meters
Solar declination
δ
radians
Solar time angle at the beginning of period
ω1
radians
Solar time angle at the ending of period
sin(ω1)
ω2
radians
Solar time angle at midpoint of period
sin(ω2)
ω
radians
Length of the step (applies to hourly step only)
t1 = 1
hour
Extraterrestrial radiation
Ra
MJ/m2/hour
Clear sky radiation
RSO
MJ/m2/hour
Ratio of radiation
Rs/RSO
no units
Ratio of radiation with total cloud cover
Rs/RSO= 0.3
no units
Ratio of radiation at nighttime in humid, subhumid climates
Rs/RSO= 0.4 to 0.6
no units
Ratio of radiation at nighttime in arid, semi-arid climates
Rs/RSO= 0.7 to 0.8
no units
Constant used in calculating Ra
as= 0.75
Constant used in calculating Ra,
bs*Z = 2 x 10-5*Z
(Z = elevation in meters)
Short wave, high energy radiation
Rns
MJ/m2/hour
A-11
Appendix A. Evapotranspiration, Vapor Pressure Deficit, and Crop Water Needs
SIGMA = 2.043 x 10 -10
Stefan-Boltzmann constant
SIGMA*(absolute temp)4
MJ/m2/K4/hour
MJ/m2/hour
Long wave, low energy radiation
Rnl
MJ/m2/hour
Net radiation (short wave-long wave radiation)
Rn
MJ/m2/hour
Soil heat flux (if Rs>0 then 0.1*Rn, else 0.5*Rn)
G
MJ/m2/hour
Net radiation - soil heat flux
(Rn-G)
MJ/m2/hour
Denominator (Denom) in the equation for calculating ETo
Denom = Δ + γ (1+0.34 u2)
First term in the equation for calculating ETo
First term = 0.408 * Δ * (Rn-G) / Denom
Second term in the equation for calculating ETo
Second term =(γ * (37/(T+273)) * u2* (eo-ea)) /
Denom
Hourly ETo value
ETo (mm/hour) = first term + second term
REFERENCES
A-12
1.
Crop Evapotranspiration, Guidelines for Computing Crop Water
Requirements, FAO Irrigation and Drainage Paper 56, Richard G. Allen,
Luis S. Pereira, Dirk Raes, and Martin Smith, Food and Agriculture
Organization of the United Nations, Rome, 1998.
2.
'Uber einige meteorologische Begriffe' , Tetens,O. , Z. GeoPhys., 6:297309, 1930.
3.
'On the computation of saturation vapor pressure', Murray, F.W., J. Appl.
Meteor., 6:203-204, 1967.
Appendix B. Growing Degree Days (GDD)
B.1 Growing Degree Days
This section explains the concept of growing degree-days (GDD) and methods
used in VisualWeather to calculate its hourly values.
Growing degree-days (GDD) is a measure of temperature condition that is
favorable to plant growth. A range of temperatures is defined by entering
lower and upper temperature limits. Temperatures lying within these limits are
assumed to be conducive for growth of a given plant. The lower and upper
limits of temperatures favorable to plant growth vary from plant-to-plant and
are provided by the user. Generally, temperatures above 50°F (10°C) are
considered favorable for plant growth.
B.1.1 Method
1.
An hourly average temperature value, Ta, is compared to the upper and
lower temperature limit.
2.
If Ta > upper temperature limit, then Ta is set equal to upper temperature
limit, and
If Ta < lower temperature limit, then Ta is set equal to lower temperature
limit.
3.
If upper temperature limit >Ta > lower temperature limit, then
GDD = Ta- lower temperature limit is calculated for every hour.
4.
The 24 hourly GDD values are summed.
The GDD value calculated per day is added to the previous day's GDD value.
This process is continued and a cumulative GDD value is reported. When the
cumulative GDD value reaches a threshold for a given plant value, as judged
by a user, then it is assumed that it has grown to an extent where it must be
trimmed.
B-1
Appendix C. Dew Point
C.1 Dew Point
Dew point is the temperature at which air saturates, upon cooling, without
change in its water content.
C.1.1 Method
1.
The value of saturation vapor pressure, es (kPa), is calculated using the
polynomial in Ta, the air temperature1
es=(a0 + Ta*(a1+Ta*(a2+Ta*(a3+Ta*(a4+Ta*(a5+a6*Ta))))))*0.1; (1)
where Ta is the mean hourly temperature and the polynomial coefficients
are:
a0=6.107799961;
a3=2.650648471E-4;
a6=6.136820929E-11;
a1=4.436518521E-1;
a4=3.031240396E-6;
a2=1.428945805E-2;
a5=2.034080948E-8;
The quantity es is in mbars. Since 1000 mbars = 100 kPA, 1 mbar = 0.1
kPa. Thus, multiplying the polynomial result by 0.1 converts es from
mbar into kPa.
2.
The vapor pressure, ea (kPa), is calculated from ea = RH * es/100, where
RH is a measured value of relative humidity (%).
3.
The dewpoint, Td (Celsius), is calculated using the equation2
Td = C3 *ln(ea/ C1) / (C2-ln(ea/ C1))
(2)
where C1 = 0.61078, C2 = 17.558, and C3 = 241.88
C.2 References
1.
'An Approximating Polynomial for the Computation of Saturation Vapor
Pressure', Lowe, P.R., J. Appl. Meteor., Volume 16, Issue 1: 100-103,
January 1977.
2.
'Uber einige meteorologische Begriffe', Tetens,O. , Z. GeoPhys., 6:297309, 1930.
C-1
Appendix D. Wind Chill
D.1 Wind Chill
Wind chill is a degree of ‘coldness’ experienced by exposed human skin due to
increasing wind speeds at a given ambient temperature. Wind chill
temperature drops with increasing wind speeds at a constant air temperature or
with decreasing air temperatures at a constant wind speed. The wind chill
effect is more pronounced when the wind speed increases and air temperature
drops. Since the degree of coldness varies from person-to-person, the wind
chill may have different meaning to different individuals in the same
environment.
Wind chill temperatures are meaningful at wind speeds between 3 mph and 110
mph and temperatures between -50°F and 50°F. If either measurement is
outside of these boundaries, the wind chill will be reported as N/A.
D.1.1 Method
The wind chill equivalent temperature (°F) can be obtained by using the
following equation[1]:
Wind Chill (°F) = 35.74 + 0.6215T – 35.75 (V0.16) + 0.4275T (V0.16)
where, T = Air Temperature in °F and V = Wind Speed in mph.
VisualWeather calculates wind chill from the raw data of average values of
temperatures and wind speeds. Users need not enter any parameters to
calculate the wind chill.
D.2 References
1.
Bulletin of the American Meteorological Society, pp. 1743-1744, Vol. 74,
No. 9, September 1993.
2.
National Weather Service Announcement, August 2001,
http://205.156.54.206/er/iln/tables.htm.
D-1
Appendix E. Chill Hours
E.1 Chill Hours
Chill hours represent the number of hours the temperature stayed at or below a
certain base (or reference) temperature provided by the user.
E.1.1 Method
1.
The hourly average temperature value, Ta, is compared to the base
temperature.
2.
If Ta < = BaseTemp, then the number of chill hours = 1, and
If Ta > BaseTemp, then the number of chill hours = 0
3.
A value of either 1 (if the hourly average temperature stayed at or below
the base temperature) or 0 (if the hourly average temperature stayed above
the base temperature) is assigned to each hour of the day.
4.
These values are summed at the end of each 24-hour period. The total
value represents the number of chill hours; i.e., the number of hours the
temperature remained at or below the base temperature.
E-1
Appendix F. Heat Index
F.1 Heat Index
Heat index is the perceived temperature as influenced by relative humidity.
For example, an air temperature of 90°F would feel like 132°F if the RH was
100%.
The equation is only useful if air temperature > 80°F (27°C) and relative
humidity > 40%. VisualWeather will report the wind chill as N/A if air
temperature is < 80°F (27°C) or relative humidity < 40%.
F.1.1 Method
Heat index equivalent temperature (°F) can be obtained by using the following
equation[1].
HI = -42.379 + 2.04901523T + 10.14333127R - 0.22475541TR - 6.83783x103 2
T - 5.481717x10-2R2 + 1.22874x10-3T2R + 8.5282x10-4TR2 - 1.99x10-6T2R2
where, HI = heat index in °F, T = air temperature in °F, and R = relative
humidity in percent (e.g., 30).
VisualWeather calculates heat index from raw data of average values of
temperature and relative humidity. Users need not enter any parameters to
calculate heat index.
F.2 References
1.
The equation used in this calculation is from the National Weather
Service; a good explanation may be found at
http://www.srh.noaa.gov/bmx/tables/hindex.html
2.
Campbell Scientific also has a "Heat Index" Application Note at
ftp://ftp.campbellsci.com/pub/outgoing/apnotes/heatindx.pdf
F-1
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