Emissive Reflector Correction in the Legacy Version 1B11 V8 (GPM05) Brightness Temperature of the TRMM Microwave Imager

The Tropical Rainfall Measurement Mission (TRMM) observatory has provided nearly a two-decade time series of precipitation measurements, which is very beneficial for scientific understanding of the Earth's hydrological cycle. This paper concerns the passive microwave sensor named the TRMM microwave imager (TMI) and the development of the legacy version TMI 1B11 V8 (GPM05) brightness temperature data product that will be released in late 2017. In particular, this version-8 includes a robust main reflector emissivity (brightness temperature, Tb ) correction that is based upon rigorous electromagnetic principles and on-orbit radiometric measurements. This emissivity correction process involves two steps, namely, the derivation of the main reflector emissivity coefficients for each TMI channel by analyzing deep space maneuvers and the determination of the reflector physical temperature for the entire 17-plus-year time series by analyzing the single difference between the measured T b and the simulated Tb from a radiative transfer model.