Version 07 is the current version of the data set. Older versions are no longer available and have been superseded by the current version.

Consistent rainfall retrievals from each instrument mandate the basic sensor radiance measurements (brightness temperature, Tb) to be consistently inter-calibrated.

Fundamental to this concept is the existence of the GPM Microwave Imager (GMI), a conically scanning multifrequency radiometer in non-sun-synchronous orbit, which serves as a radiometric transfer standard for the other passive microwave sensors on cooperative (polar orbiting) constellation satellites. This GPM inter-satellite calibration process is known as XCAL.

GMIBASEXCAL is the standard GMI calibration product with reduced precision of all physical fields. It consists of one full orbit with no overlaps to other orbits in the production although up to 200 overlap scans may be used for multi-scan calibration in the process.

This GPM GMI product contains "GMI Antenna Temperatures", and is written as a multi-Swath Structure. Swath S1 has channels 1-9: 10V 10H 19V 19H 23V 37V 37H 89V 89H. Swath S2 has channels 10-13: 166V 166H 183+/-3V 183+/-8V. S3 S4 are full rotation versions of S1 S2.