As the reference radiometric calibration standard of sensors on the Haiyang-1C (HY-1C) satellite platform, the satellite calibration spectrometer (SCS) is equipped with an onboard calibration system composed of double solar diffusers and an erbium-doped diffuser to monitor the postlaunch radiometric response change. Herein, through onboard calibration data analysis, the calibration diffuser performance remains stable without degradation, and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra is adopted as a reference to repeatedly verify onboard radiometric calibration results by selecting different dates and reflectance scenes. The SCS equivalent reflectance is obtained by combining the mean digital number (DN) of the SCS crossing area image with the radiometric calibration coefficient. The spectral reflectance is obtained via interpolation and iteration, which is adopted as the actual MODIS incident pupil spectral reflectance because the small imaging time interval can be ignored and almost vertically observed, and it is convoluted with the MODIS spectral response function to obtain the predicted equivalent reflectance. Validation is completed by comparing the predicted MODIS equivalent reflectance to the measured value based on the onboard calibration coefficient. The results show that (1) the difference between the measured and predicted MODIS band equivalent reflectance is between -0.00466 and 0.0039, and (2) the percentage difference between the measured and predicted MODIS band equivalent reflectance ranges from 4.17% and 1.24%, indicating that the calibration system carried on HY-1C can perform high-precision SCS radiometric calibration, meeting the cross-calibration accuracy requirements of other loads on the same platform.

中文翻译：

---

HY-1C的卫星绝对光谱仪的机载绝对辐射定标和验证

作为海阳1C（HY-1C）卫星平台上传感器的参考辐射校准标准，卫星校准光谱仪（SCS）配备了由双太阳散射器和掺er散射器组成的机载校准系统，用于监视发射后辐射响应变化。在此，通过机载校准数据分析，使校准漫射器性能保持稳定而不劣化，并采用Terra的中分辨率成像光谱仪（MODIS）作为参考，通过选择不同的日期和反射率场景来反复验证机载辐射校准结果。SCS等效反射率是通过将SCS交叉区域图像的平均数字（DN）与辐射校准系数相结合而获得的。光谱反射率是通过插值和迭代获得的，由于小的成像时间间隔可以忽略并且几乎可以垂直观察到，因此被用作实际的MODIS入射光瞳光谱反射率，并通过MODIS光谱响应函数进行卷积以获得预测的等效值。反射率。通过根据机载校准系数将预测的MODIS等效反射率与测量值进行比较，可以完成验证。结果表明：（1）测量和预测的MODIS波段等效反射率之间的差异在-0.00466和0.0039之间，（2）测量和预测的MODIS波段等效反射率之间的百分比差异在4.17％和1.24％之间，