Creating a Consistent Multi-Decadal Oceanic TRMM-GPM Brightness Temperature Data Record

Abstract

Intercalibrating the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) to the Global Precipitation Measuring (GPM) Microwave Imager (GMI) is necessary for generating a consistent multi-decadal brightness temperature (Tb) data record that covers TRMM and GPM eras. However, TMI and GMI share only a 13-month common operational period (2014-2015). Fortunately, the polarimetric radiometer WindSat launched in 2003, has been vetted to be well-calibration, and exceptional long-term radiometric stability between WindSat and TMI over >8-year period (2005–2014) has been exhibited. Therefore, WindSat can be used as the calibration bridge to achieve a seamless transfer between TMI and GMI Tb time series. In this paper, TMI will be first intercalibrated to GMI for their 13-month overlap period, and then intercalibrated to WindSat for their >12 years period (2003–2015). Thus, a multi-decadal oceanic Tb dataset will be created to ensure a consistent long-term precipitation record that covers TRMM and GPM eras. Moreover, to quantify the Tb uncertainty of this dataset, an uncertainty estimation model considering various sources of uncertainties will be applied to both intercalibration processes. These results will allow the further study in potential climate trends and changes in the variability.