Validation of FY-3B MWRI Rain Rate over China

As part of the collaboration between China Meteorological Administration (CMA) National Meteorological Information Centre (NMIC) and NOAA Climate Prediction Center (CPC), a new system is being developed to construct half hourly satellite precipitation estimate on a 0.05olat/lon grid over China by combining NOAA series, DMSP series, and CMA FY-3B Polar Microwave rain rate with TMI rain rate. Foundation to the development of the PMW rain rate combining algorithm is the validation of those passive microwave (PMW) - based rain rate retrievals. Since FY-3B is new and not included as inputs to CMORPH, and other established high-resolution satellite precipitation products, we focus our work here on the validation and error quantification of the FY-3B PMW rain rate retrievals. This is done by comparisons with the combined PMW product (MWCOMB) of NOAA/CPC and against a gauge-based analysis of hourly precipitation over China derived from gauge reports of dense station networks.

Overall, the monthly mean rain rate distribution of FY-3B agrees very well with MWCOMB except for a little under-estimate over ocean. In the latitudinal profiles, we can see a very close agreement between the FY-3B retrievals and the MWCOMB over land, but there is an obvious general under estimates over ocean. Pattern correlation between FY-3B and MWCOMB is relatively high over both land and ocean. From more works on PDF check of 30-min precipitation, over a 0.25„a grid, we can clearly see FY3B presents lower PDF for weak precipitation, especially over ocean and reasonable agreements in PDF over land.

A gauge-based analysis of hourly precipitation derived from over 30000 station reports is used to validate FY-3B PMW rain rate. In order to compare, 7 PMW rain rate of different satellite, including TMI, NOAA-18, NOAA-19, Metop-A, DMSP-S16, DMSP-S17, DMSP-S18, are also compared with the gauge-based analysis. FY-3B's bias is a little higher than NOAA-18 over whole China, western China and eastern China. Detailed results will be reported at the conference.