The Tropical Rainfall Measuring Mission (TRMM) is a joint U.S.-Japan satellite mission to monitor tropical and subtropical precipitation and to estimate its associated latent heating. TRMM was successfully launched on November 27, 1997 at 4:27 PM (EST) from the Tanegashima Space Center in Japan.
The purpose of the TRMM Ground Validation (GV) program is to develop validation methods and to obtain ... reliable surface-based data during the TRMM mission, with which the TRMM satellite measurements can be verified.
The TRMM GV network consists of four primary or direct data (DD) sites and seven direct product (DP) sites. The four DD sites are Darwin, Australia; Melbourne, Florida; Houston Texas; and Kwajalein. The seven DP sites are located in Taiwan, Israel, Thailand, Brazil, Guam, and special climatology-multiple radar sites in Florida and Texas.
TRMM_GV_1B51 contains the raw radar volume scans collected at the four primary GV sites. A threshold value of -15 dBZ is applied to the raw radar reflectivity. Data are truncated at 230 km (slant range). Some correction factors are mathematically added to the appropriate fields, generally related to the radar platform. Each file stores multiple volume scans collected over hourly intervals for a site. Data include reflectivity (dBZ), differential reflectivity (dB), and Doppler velocity (m/s), over a maximum range of 230 km radius from the radar.
The data are stored in the Hierarchical Data Format (HDF), which includes both core and product specific metadata. The file size is about 29 MB for Darwin and about 6 MB for the other sites (compressed).