利用EDS／MODIS交叉定标FY1D／VIRR可见光-近红外通道

以EOS/MODIS的星上定标结果为标准,采用交叉定标方法标定FY1D/VIRR的可见光-近红外通道。先获得两个传感器的配对通道,然后利用6S模式计算出他们的匹配因子,根据EOS/MODIS的观测敦煌辐射校正场扫描计数值和星上定标结果以及它和FY1D/VIRR的匹配因子计算出FY1D/VIRR同时观测敦煌辐射校正场时的表观辐亮度和表观反射率,最后将得到的表观辐亮度和表观反射率与FY1D/VIRR观测敦煌辐射校正场的计数值进行比较,就得到了FY1D/VIRR通道的绝对定标系数。将本次定标结果与敦煌场地定标试验的定标结果比较,定标结果一致性较好,并可用于对发射前定标偏差进行校正。

Radiometric Cross-calibration of the FY1D/VIRR and EOS/MODIS in the Visible and Near-infrared Spectral Bands

In this paper, the visible and near-infrared spectral bands of FY1D/VIRR were calibrated using cross-calibration methods based on the EOS/MODIS. First, the match bands of the two sensors were obtained. Then the 6S code was run to calculate their band match factor, and the apparent radiance and reflectance of the FY1D/VIRR were gained according to the digital numbers of the EOS/MODIS when the satellite over passed the Dunhuang Radiometric Calibration Site, onboard calibration results and match factors. After comparing the apparent radiance and reflectance to the digital numbers of the FY1D/VIRR when FY1D over passed the Dunhuang Radiometric Calibration Site at the same time, the calibration coefficients were obtained. The consistency between the results of this cross-calibration and those of site test was good. The method could be used to validate the pre-launch calibration results.