4. Data Access
4.1 Getting Data
There are two basic ways to get TOVS Path-A and -B data from GES DISC: i) Anonymous FTP, and ii) Interactive search using Mirador.
- Anonymous FTP: ftp://disc1.gsfc.nasa.gov/data/s4pa/tovs
The directory tree on the FTP server have the patterns:
TOVSA [D,5,M] [NT,NF,NG,NH,ND] Or
TOVSB [D,5,M] [NG,ND]
Where:[NT,NF,NG,NH,ND] - which satellite, correspondingly: TIROS-N, NOAA-F,G,H,D
A,B - Path-A,B
[D,5,M] - stands for Daily, 5-day (pentad), and Monthly
Interactive, Mirador: http://mirador.gsfc.nasa.gov
4.2. Working with HDF files
The Path A and B data currently supported by GES DISC are in HDF4 format, and are "externally" compressed. They need to first be "unzipped", before attempting to read the files with any HDF-compatible software package or tool. The utility "gzip" can do the unzipping. To open and read the uncompressed HDF file, various packages and tools can be used: IDL, MatLab, Fortran, HDFview, etc. (NASA does not endorse one commercial package over another.)
Command-line utilities from the HDF Group, like ncdump and hdp, can be used to quickly see the file content, and even dump out data in binary or ASCII (text) format. The HDF Group also provides a simple tool with java-based user interface, HDFView. This tool is very convenient to explore HDF files content, and produce simple graphic and image previews. From the command-line utilities, the hdp with the "dumpvd" option, makes it extremely easy to see TOVS data file annotation. E.g.:
hdp dumpvd TOVS_5DAYS_AM_B940131.E940204_ND.HDF
will print on the monitor a detailed annotation for the dataset.
Simple Fortran routines, legacy from earlier years of TOVS support, can be found in this TAR archive. They, however, need to be compiled. Compiling guidance is provided in the README packaged with the fortran code in the TAR.