The Level-1A Product file, "1A11", is a concatenation of Header record, Spacecraft Attitude packets, TMI Housekeeping packets, TMI Science Data packets, QACs and an MDUL. As such, it is reversible to Level 0. The header record contains information pertaining to orbit times, orbit number, times of the first scan, and number of scans, among other things. The Level 0 data contain the actual channel data expressed as"sensor counts". A Level 1A file contains data for a single orbit and has a file size of about 31 MB (uncompressed).
Spatial coverage is between 38 degrees North and 38 degrees South owing to the 35 degree inclination of the TRMM satellite. This orbit provides extensive coverage in the tropics and allows each location to be covered at a different local time each day, enabling the analysis of the diurnal cycle of precipitation.