A rapid assessment of MWRI-RM/FY3G brightness temperature

Abstract

The Microwave Radiation Imager for the Rainfall Mission (MWRI-RM) onboard the FengYun 3G satellite (FY3G), launched in April 2023, will provide massive brightness temperature (Tb) measurements at 17 frequencies from 10.65 GHz to 183 GHz. The operationally calibrated MWRI-RM Level 1B Tb data have been released since 23 October 2023. The MWRI-RM measurements are compared with the simultaneous measurements from the GPM Microwave Imager (GMI) to provide a first overview of the MWRI-RM measurement quality. A radiative transfer model (RTM) is performed for the double difference (DD) analysis. The results show that the Tbs of MWRI-RM are in good agreement with those of GMI, with mean bias error (MBE) and root-mean-square error (RMSE) values of less than 1 K for most channels. Larger differences are observed at the horizontal polarization of 36.5 and 89 GHz, with an RMSE of about 2 K. RTM simulations reflect that the Tb difference between MWRI-RM and GMI due to the different Earth incidence angle of the sensors is about 0.5 K over the sea. The DD analysis results suggest that MWRI-RM demonstrates quite similar performance to GMI for most channels, especially for the first used channels at 166 GHz and 183 GHz.

摘要

2023年4月发射的FY-3G上搭载17个频率的测雨微波成像仪 (MWRI-RM) , 其业务定标的微波亮温 (Tb) 数据于2023年10月23日公开发布. 本文比对了发布10天的MWRI-RM与全球降水测量 (GPM) 卫星上的微波成像仪 (GMI) 相匹配的Tb数据, 并借助辐射传输模式进行双差分 (DD) 交叉定标分析, 旨在快速评估新一代MWRI-RM观测数据质量. 观测比较表明, MWRI-RM 与 GMI测量的Tb一致性很好, 大多通道的平均偏差 (MBE) 和均方根误差 (RMSE) 均小于 1 K. 两种传感器由于观测角度略有不同在水面产生约 0.5 K差异. DD分析也展示出MWRI-RM的大多数通道性能与GMI相当接近, 尤其是首次启用的高频166 GHz和183 GHz.