This is the new (GPM-formated) TRMM product. It replaces the old TRMM_1A01

    Version 08 is the current version of the data set. Previous versions have been superseded by Version 08.

The 1AVIRS product contains science and housekeeping sensor count data directly from the Visible and Infrared Scanner (VIRS) aboard the TRMM satellite. The data has been unpacked from the spacecraft packets and geolocated. A Level 1A file contains data for a single orbit and has a file size of about 131 MB. There are 16 files of VIRS 1A data produced per day.

The Visible and Infrared Scanner (VIRS) is a five-channel visible/infrared radiometer, which builds on the heritage of the Advanced Very High Resolution Radiometer (AVHRR) instrument flown aboard the NOAA series of Polar-Orbiting Operational Environmental Satellites (POES). The VIRS detects radiation at 1 visible, 2 near infrared and 2 thermal infrared wavelengths, allowing determination of cloud coverage, cloud top height and temperature, and precipitation indices. The central wavelengths for the VIRS channels are 0.63, 1.60,3.75, 10.8, and 12.0 microns. All channels are in operation during the daytime, but only channels 3, 4 and 5 operate during the nighttime.

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