Progress on FCDR of MWRI onboard FY-3 Series Satellites

A long time series fundamental climate data record (FCDR) have been developed using operational L0 data from Microwave Radiation Imager (MWRI) onboard FengYun-3 series satellites. This FCDR contains re-calibrated brightness temperature data from three MWRIs mounted on FY-3B/3C/3D satellites from 2010 to 2021. Corresponding to the very unique on-orbit calibration system design of MWRI, the calibration error of the sensors may come from the hot-load reflector back-lobe, hot-load reflector emissivity, hot-load efficiency, cold reflector RFI, and receiver non-linearity. Therefore, a comprehensive error analysis is performed by using the double-difference (DD) method. GPM Microwave Imager (GMI) data are also used as a reference sensor. Simultaneous Conical Overpassing (SCO) method is selected to sample the paired data from two satellites. Based on temporal and spatial SCO rules, the required DD thresholds over a stable ocean surface or rain forest is determined and the optimized re-calibration parameters are derived from the multiple iterations. After reprocessing, the obvious improvement for all channels from 10GHz to 89GHz is shown in the root mean squared error (RMSE) of MWRI with respect to GMI which is significantly reduced from 5K to 1K. The RMSE of all 3 instruments and all channels is decreased to less than 1.5K. Most of the channels' RMSE is around 1K or even less. The bias time series between MWRI and GMI also shows very stable from 10GHz/18GHz.

Recently, some typical climate parameters retrieval using FCDR of MWRI have been done by different researchers, including sea ice concerntration, soil moisture, soil frozen and thaw detection, land surface microwave emissivity. The results are very encourage compared with operational MWRI datasets.