风云三号A星微波湿度计（FY-3A/MWHS）是我国首次在轨定量遥感大气参数的高频微波辐射计，本文以发射前地面真空试验数据为基础完成了FY-3A/MWHS在轨辐射定标，利用同期在轨的同类载荷NOAA/AMSU-B数据进行在轨辐射定标对比分析，结果表明FY-3A/MWHS在轨星上定标观测基础数据在卫星绕地飞行一圈的观测过程中变化合理，经非线性偏差订正和天线订正等辐射定标处理后，FY-3A/MWHS与NOAA-17/AMSU-B对应通道定标结果相比匹配目标点通道亮温差最大不超过1.5 K，FY-3A/MWHS在轨辐射定标结果为其资料在数值天气预报模式中的同化以及大气参数反演等定量应用奠定了基础。FY-3A/MWHS定标及结果分析方法对我国未来星载被动微波探测器的在轨定量应用具有示范意义。

In this paper, the method for FY-3A/MWHS calibration in-orbit has been introduced. Radiometric calibration of FY-3A/MWHS on orbit has been performed based on the T/V test results and surface lab performances test results. It is confirmed that the system of radiometric calibration for MWHS is successful, and performs well on orbit. The variations among space views and warm target views in the interval of scan lines are generally within 20 counts. And the temperature fluctuation of warm target is within 0.5 K in a single pass. Due to the accuracy of the nonlinearity parameters, the radiance calibration of MWHS agrees well with NOAA-17/AMSU-B. The brightness temperature differences between FY-3 MWHS and NOAA-17/AMSU-B at simultaneous cross overpass points are less than 1.5 K. That is the foundation of quantitative application for the data of FY-3A/MWHS in numerical weather prediction(NWP). The method of calibration and validation for FY-3A/MWHS will be a good demo for the other passive microwave sounder in the future.