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为获取2013年HJ-1B/IRS热红外通道(B08)绝对辐射定标系数,以TERRA/MODIS为参考传感器,以青海湖为研究区域,采用双通道差分模型进行交叉定标。对比分析不同观测角度、成像时差对定标精度的影响,结果表明,参考传感器观测角度30°以内、成像时差1 h左右交叉定标条件最佳,且回归拟合的定标系数精度最高。通过采用2013年10月26日宁德附近海域星地同步实验数据进行精度验证,结果表明,此定标系数得到的表观辐亮度误差在0.02 Wm-2μm-1sr-1以内,表观亮温误差在0.15℃以内。同时,通过与历年辐射定标系数(2008~2012年)进行对比,所得定标系数精度分别提高98.50%、98.24%、90.21%、20.87%和98.31%。总之,此文定标系数精度较高、结果可靠,可应用于IRS B08通道。
In order to obtain the absolute radiation calibration coefficient of HJ-1B / IRS thermal infrared channel (B08) in 2013, a dual-channel differential model was used for cross calibration with TERRA / MODIS as the reference sensor and Qinghai Lake as the research area. The results show that the cross-calibration condition is best when the reference sensor observation angle is within 30 ° and the imaging time difference is about 1 h, and the precision of the calibration coefficient of regression fitting is the highest. The accuracy of the experiment was verified by using the satellite synchronization data from the sea near Ningde on October 26, 2013. The results show that the apparent radiance error of this calibration coefficient is within 0.02 Wm-2μm-1sr-1, and the apparent bright-temperature error Within 0.15 ℃. At the same time, the precision of the calibration coefficient is improved by 98.50%, 98.24%, 90.21%, 20.87% and 98.31% respectively compared with the radiation calibration coefficient over the years (2008 ~ 2012). In conclusion, the accuracy of the proposed calibration coefficient is high and the result is reliable, which can be applied to the IRS B08 channel.