Abstract. This study analyzes the response changes of the Medium Resolution Spectral Imager II (MERSI-II), which is an optical instrument on the Fengyun-3D satellite, during different periods since liftoff. The study was based on the Dunhuang radiometric calibration site. The solar reflective channels, assessed using the reflectance-based method, showed a degradation of MERSI-II. The degradation rate of change was found to be higher in the beginning of the mission and to be decreasing with time. The latest calibration results show that the decrease in instrument response between 440 and 900 nm in the near-infrared band was relatively small compared to the previous official calibration coefficient, with an average attenuation rate of ∼5.3 % . It was observed that the MERSI-II shortwave channel had a large attenuation of 21%, especially in the 412 nm band. The calibration method and parameter processing of the reflectance-based method are introduced in detail. The accuracy of the calibration process was tested using Moderate Resolution Imaging Spectroradiometer, an internationally recognized high-precision satellite instrument, which determined the calibration error to be <4 % . The experimental results contribute to the improvement in the accuracy of satellite observation and the design of subsequent equipment.

中文翻译：

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风云3D中分辨率光谱成像仪-II绝对辐射定标及辐射特性分析

摘要。本研究分析了风云3D卫星上的光学仪器MERSI-II中分辨率光谱成像仪II（MERSI-II）在升空后不同时期的响应变化。该研究基于敦煌辐射校准站点。使用基于反射率的方法评估的太阳反射通道显示出 MERSI-II 的降解。发现变化的退化率在任务开始时较高，并随着时间的推移而下降。最新的校准结果表明，与之前的官方校准系数相比，近红外波段 440 至 900 nm 之间仪器响应的下降幅度较小，平均衰减率为 5.3%。观察到 MERSI-II 短波信道有 21% 的大衰减，特别是在 412 nm 波段。详细介绍了基于反射率的方法的标定方法和参数处理。校准过程的准确性使用国际公认的高精度卫星仪器中分辨率成像光谱仪进行测试，确定校准误差<4%。实验结果有助于提高卫星观测精度和后续设备的设计。