In-Orbit Calibration Uncertainty of the Microwave Radiation Imager on board Fengyun-3C  

作　　者：Xinxin XIE Wanting MENG Jiakai HE Weimin YU Xue LI 

机构地区：[1]School of Atmospheric Sciences,Sun Yat-Sen University,Zhuhai 519082 [2]Key Laboratory of Tropical Atmosphere-Ocean System,Ministry of Education,Zhuhai 519082 [3]Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082 [4]Shanghai Spaceflight Institute ofTT&C and Telecommunication,Shanghai 201109

出　　处：《Journal of Meteorological Research》2021年第6期943-951,共9页气象学报（英文版）

基　　金：Supported by the National Key Research and Development Program of China(2018YFB0504900 and 2018YFB0504902);National Natural Science Foundation of China(41805024 and 42005105);Open Fund of the State Key Laboratory of Hydroscience and Engineering and Tsinghua University–Ningxia Yinchuan Joint Research Institute of Digital Water Governance with Internet of Waters(sklhse-2021-Iow08)。

摘　　要：This study evaluates the in-orbit calibration uncertainty(CU)for the microwave radiation imager(MWRI)on board the Chinese polar-orbiting meteorological satellite Fengyun-3 C(FY-3 C).Uncertainty analysis of the MWRI provides a direct link to the calibration system of the sensor and quantifies the calibration confidence based on the prelaunch and postlaunch measurements.The unique design of the sensor makes the uncertainty in the calibration of the sensor highly correlate to the uncertainty in the brightness temperature(TB)measured at the hot view,while the cold view has negligible impacts on the calibration confidence.Lack of knowledge on the emission of the hot-load reflector hampers the MWRI calibration accuracy significantly in the descending passes of the orbits when the hotload reflector is heated nonuniformly by the solar illumination.Radiance contamination originating from the satellite and in-orbit environments could enter the primary reflector via the hot view and further impinge on the CU,especially at the 10.65-GHz channels where the main-beam width is much broader than that of higher-frequency channels.The monthly-mean CU is lower than 2 K at all channels,depending on the observed earth scenes and in-orbit environments,and the month-to-month variation of CU is also noticed for all channels.Due to the uncertainty in the emissive hot-load reflector,CU in the descending passes is generally larger than that in the ascending orbits.Moreover,up to 1-K CU difference between the ocean and land scenes is found for the 10.65-GHz channels,while this difference is less than 0.1 K at the 89-GHz channels.

关 键 词：calibration uncertainty(CU) microwave radiation imager(MWRI) Fengyun-3(FY-3) 

分 类 号：P414.4[天文地球—大气科学及气象学] V474.24[航空宇航科学与技术—飞行器设计]