微波成像仪是我国风云三号系列气象卫星重要微波遥感仪器之一。本项目基于风云三号微波成像仪定标方程分析风云三号微波成像仪在轨观测数据，提高微波成像仪在轨定标精度，为数值天气预报同化系统提供可靠观测资料。.从物理根源上解释并修正微波成像仪升降轨偏差是本项目的主要研究创新点。本研究针对风云三号微波成像仪自身频率和带宽设计筛选出晴空条件观测场景；对升轨和降轨两种情景分别进行讨论，通过建立观测亮温与热镜物理温度函数关系修正微波成像仪定标方程中的热镜发射率，达到订正升降轨偏差的目的；最后，利用最低亮温方法验证修正后的仪器定标精度。该研究将为我国风云三号气象卫星搭载的微波成像仪以及我国正在研制的各类型微波辐射计在轨定标算法研究和定标系统设计研发提供重要的理论依据和支持。

Microwave radiometer imager (MWRI) on board FengYun-3 (FY-3) Meteorological Satellite in China is regarded as one of the most important instruments for microwave radiometry. This study will correct the ascending-descending bias of FY-3 MWRI to improve its on-orbit calibration accuracy. Thus, reliable observations will be provided for further data assimilation in numerical weather predictions. .This study proposes a physical-based correction algorithm for MWRI calibration instead of traditional empirical correction. We will establish a relationship between the observed brightness temperature (TB) and the physical temperature of the hot load reflector at ascending and descending passes for all channels, following an analysis of cloud/precipitation screen and data quality control based on FY-3 MWRI specifications. Calibration accuracy will be verified with the vicarious cold calibration method. The algorithm proposed in this study will be used for post-launch calibrations of FY-3 MWRIs and will be beneficial to ongoing research and further instrument design.