Linked to the metadata record for each voyage are several files, including:
1. .log file containing the sea ice and meteorological data. This is a binary file that can be read using the seaice.exe program written specifially or Antarctic sea ice observations (Worby, 1999). The software can be downloaded from the provided url (sea ice software).
2. .txt file containing the sea ice and meteorological data.
3. .ps file containing a plot of the data around Antarctica.
1 General Description of seaice.exe software
Each data file can be observed using purpose-built software called seaice.exe, which can be downloaded from this site. This software can be used to view the data, calculate basic statistics, plot the data on an XY Cartesian graph or the cruise track on a polar stereographic map. The data can also be output to a text file for further processing. A brief overview of the software is given below. A complete user's guide, and more information about ASPeCt and the sea ice observation program can be obtained from the ASPeCt web site http://www.antcrc.utas.edu.au/aspect) or on CD-ROM [Worby, 1999].
2 Data File Format
The program stores observation records to a disk file in binary format. Thus the files cannot be viewed or printed directly. The reason for using a binary file format is to simplify reading and writing complex data records to disk reliably and rapidly. The program provides a facility to create text file listings from binary data files. These text files can be viewed and printed.
The minimum hardware configuration to run the program is:
· IBM-PC or compatible with 4MB of memory.
· Windows 3.11 or higher.
· Colour graphics display with pixel resolution better than 800 x 600, 16 colours. Screens with a lower resolution (e.g., 640 x 480) will work but are not as practical.
· 400 kbytes of disk space is required for the program, as well as sufficient disk space for the data files. Each hourly observation requires approximately 550 bytes of disk space.
To install the program, create a subdirectory on the hard disk where the program will reside. Then copy the required files:
SEAICE.EXE This is the executable version of the software.
GRID.VBX This is a system file that must be copied to enable the executable to run.
LANDMASK.MAP This is a file of latitude and longitude points around the Antarctic coastline and is used for plotting purposes.
Run the executable file (seaice.exe) from Windows by double clicking the icon. When you run the executable a new file (seaice.cfg) will be created, which stores the software configuration information. This file is automatically updated when the user changes any default settings.
4 The main Screen Layout
Running the program will produce a main screen which displays a table of daily sea ice observations. The screen has a spreadsheet format similar to the proforma for the hand-written observations. Note that all the fields are initially empty, and that a log file must be loaded before it can be displayed. To open a .log data file, or create a new .log file, choose Open Observation Log option from the File menu. The file browser dialog box appears on the screen.
All log file names must have the extension .log. If the log file exists, it will be loaded and the contents displayed on screen. If the file does not exist, an empty file will be created. The daily records of the first day containing data are displayed. The log file name will appear on the top left corner of the main window, the month list box will display the number of records for each month, and the day list box will display the number of records for each day of that particular month. By clicking on the day list box you can display the records for the particular day that is selected. To view specific sections of the record, click on any of the five buttons: View Pri, View Sec, View Ter, View Met, or Comments.
5 Convert Data To Text File
From the File menu, choose the Convert to Text File option. A dialog box appears on the screen. This function is used to generate printable text files from binary database log files.
Source Database File name This box displays the name of the database log file to convert from. It will initially be blank. Click on the << button to select a log file. A file browser box will appear. Select a file with the extension .log. When the file is loaded, the Dates From/To will default to the first and last record in the file.
Destination Text File This is the name of the destination text file. The default file name will be identical to the log file but with the extension .txt. Click on the << button to change the name of the destination file.
Date >> (From) This specifies the first record of the file to be converted to text. Pressing this button will display a dialog box with a list of records in the file. Select the required record.
Date >> (To) This specifies the last record of the file to be converted to text. Pressing this button will display a dialog box with a list of records in the file. Select the required record.
Column Fields These are the fields that may be included in the destination text file. To toggle between YES and NO click on the item.
Text File Preview After the text file is created it is displayed in this edit box. A sample output is shown below.
Convert To Text File Pressing this button will generate the text file.
Help Currently not implemented.
When you exit the dialog box, the program will prompt you to save the setup configuration to the disk file seaice.cfg. This setup configuration is loaded each time the user opens the Convert to text file dialog box. A typical text file is shown below, showing the time, date, latitude, longitude, and primary ice conditions only.
Typical sample file output:
Abbreviations used in the text file listing:
Lat: Latitude Long: Longitude
OW: Open water Conc: Ice concentration
Track: Distance of observation along ship’s route from first observation of voyage
|Primary Ice||Secondary Ice||Tertiary Ice|
|c1: primary ice conc||c2: secondary ice conc||c3: tertiary ice conc|
|ty1: primary ice type||ty2: secondary ice type||ty3: tertiary ice type|
|iz1: primary ice thickness||iz2: secondary ice thickness||iz3: tertiary ice thickness|
|f1: primary floe size||f2: secondary floe size||f3: tertiary floe size|
|t1: primary topography||t2: secondary topography||t3: tertiary topography|
|s1: primary snow type||s2: secondary snow type||s3: tertiary snow type|
|sz1: primary snow thickness||sz2: secondary snow thickness||sz3: tertiary snow thickness|
Sea T: Sea temperature in degrees C.
Air T: Air temperature in degrees C.
W Vel: Wind velocity in m/sec
W Dir: Wind direction in degrees 0359
Film: Film counter
Frame: Frame counter for the film
Video: Video recorder counter hh:mm:ss
Visib: Visibility code
Cloud: Cloud in oktas
Weath: Weather code