This file contains background information to help you get the ISAMS L2 data held at the BADC.
The ISAMS data was supplied to the BADC in VMS binary files. To enable transfer of the data to a wide variety of machines we have converted it into ASCII (plain text). To speed up transfer of the ASCII files, we have compressed them using the GNU gzip program.
Therefore, you will need gzip installed on your local system to uncompress the data files and software packages - the source code is available from software archives. You will also need to know how to use gzip and tar once you have the files on your system.
The ASCII files are purely an intermediate form for data transfer. We supply software to convert the ASCII files back into binaries on your local machine, enabling you to use software that reads the data files as binary. We also supply an example read program to read the binary data, and 3rd party software written by other users of the data, which we do not support.
2. Checking and Transferring Data from the BADC
All data and software is located beneath the directory /badc/isamsl2. Here you will find a README file and the following subdirectories:
- data - contains the gzipped ASCII data files.
- doc - contains ISAMS documentation.
- software - contains the ASCII conversion, example read and any 3rd party software available.
Check whether the data you require is available by browsing the ISAMS L2 data directories.
3. Reading the data files
3.1. Converting the data to binary on your machine
- Unzipping the files:
Unzipping the compressed ASCII files (using the gzip -d command) will typically change the size from about 2-2.5 Mbytes per file to around 10-15 Mbytes. Make sure you have sufficient disk space before unzipping the files. Note that when you convert the ascii file to a binary on your machine it will be substantially reduced in size.
- Building the software:
The ASCII to binary conversion program atobin.f is supplied in the software directory. These FORTRAN subroutines should compile on most platforms with minor changes to the open statements.
- Running the software
The conversion program will produce binary data files for your machine. The resulting binary files are considerably smaller than the intermediate ASCII files. Once the conversion is successfully completed you can remove the ASCII files.
3.2 Third Party Software
In the software directories for the ISAMS data, there is a subdirectory for 3rd Party software. If you develop software to use with the ISAMS data, then we encourage you to let us have a copy so that we can make it available to other researchers.