基于历史数据的HJ-1B/IRS热红外通道定标与分析

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-2m-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。

Calibration and analysis of HJ-1B/IRS thermal infrared channel based on the historical data

To obtain the absolute radiation calibration coefficient of IRS B08 in 2013,TERRA/MODIS was used as the reference sensor, Qinghai lake was taken as the research object, twin-channel difference model was applied to cross-calibration. By comparing the influence of different observation angles and different of imaging receiving time on calibration precision, it can be concluded that the best cross-calibration condition is the observation angle within 30 and the difference of imaging receiving time about 1 hour. Under this condition, calibration accuracy of regression fitting is the highest. According to the precision verification using satellite-ground synchronous experiment data around Ningde area on 26, October, 2013, result shows that error of apparent radiance and brightness temperature is within 0.02 Wm-2m-1sr-1 and 0.15℃ respectively. Besides, compared with the historical calibration coefficients from 2008 to 2010, the new calibration coefficients of 2013 increased by 98.50%, 98.24%, 90.21%, 20.87% and 98.31% respectively. Overall, the obtained calibration coefficient has a high accuracy, that can be used to the IRS B08.