利用青海湖水面场FY-1C气象卫星热红外窗区通道进行绝对辐射定标,由CE312野外热红外辐射计在水面测得辐亮度经大气订正传递到卫星入瞳处,考虑到大气吸收削弱影响,同时卫星观测路径大气产生热发散,这两部分对卫星信号的贡献由探空廓线和卫星观测几何输入MODTRAN37计算出来,同时进行CE312野外辐射计与卫星通道光谱响应匹配计算,最终得到卫星入瞳处的表观亮度.这个辐亮度与卫星通道的计数值比较得到该通道绝对定标系数.结果表明利用辐射校正场辐射定标与星上定标相差5%左右,相当于3K的亮温差.

This Paper describe that in flight radiometric calibration for thermal channels of FY 1C meteorological satellite sensors using Qinghai lake, water surface radiometric calibration site. The radiance of water surface measured by CE312, and then performed atmosphere correction including gas absorption and path radiance which computed by radiative transfer code MODTRAN37,predict the radiance in the satellite sensor entrance pupil. At the same time the spectral response of Satellite sensor and that of ground based sensor are coupled. At last the apparent radiance of sensor spectral channels are compared to the digital count of satellite's output to give the calibration coefficient. The result show the difference between in flight and on board calibration is about 5%, equivalent to a brightness temperature of 3 K.