FY-1C遥感器可见近红外各通道在轨辐射定标

文中通过 1999年 7月利用敦煌辐射定标场和反射率基法对FY -1C气象卫星遥感器可见 -近红外通道进行的第一次在轨辐射定标试验 ,研究和试验了卫星遥感器的在轨辐射定标方法、同步观测方法和辐射传输计算算法及其软件开发 ,有 7个通道的绝对辐射定标系数 (或称为增益和偏离量 )被获得。经过误差分析 ,认为本次定标的不确定度小于 7%。定标获得的 7个通道定标系数与该卫星发射前定标结果比较 ,其中 5个通道 (通道 1,2 ,7,8,10 )结果比较接近 ,另两个通道 (通道 6,9)由于发射前定标误差较大致使二者有一定差别。另外 ,通过 2 0 0 0年 9月份对FY -1C卫星进行的第二次辐射定标试验 ,使该卫星在轨 1a多来的运行状态得到了定量监测 ,本次定标与1999年 7月的定标结果比较 ,发现可见 -近红外各通道性能均有程度不同的衰减 ,尤其是通道 1,7,8性能衰减分别为 35% ,2 8% ,2 2 % ,而通道 2 ,6,9,10性能衰减较小 (为 10 %左右 )。

IN-FLIGHT VICARIOUS RADIOMETRIC CALIBRATION FOR VIS-NIR CHANNELS OF FY-1C SATELLITE SENSOR AT DUNHUANG SITE

First radiometric calibration for VIS-NIR channels of FY-1C meteorological satellite sensor was performed at China Dunhuang Calibration Test Site on July 7, 16 and 17,1999. The radiometric calibration adopted the reflectance-based method. First of all the ground reflectance at the test site and atmospheric parameters were obtained when FY-1C overpassed . Based on these data , a radiative transfer code (6S) was run. The apparent reflectance of FY-1C's VIS-NIR channels was obtained. By geometric registration of the satellite-ground pixels and a comparison of the mean digital counts with the apparent reflectance, the calibration coefficients (gain and offset) from seven channels of FY-1C (center wavelength: 455,505,555,630,865,932.5 and 1610 nm) were determined. An error budget of the reflectance-based calibration method shows that the uncertainty is less than 7%. Comparing the calibration results with the pre-launch calibration, a better agreement at five channels is achieved except the ones in channels 9 (555 nm) and channel 6 (1610 nm) . Second radiometric calibration of VIS-NIR of FY-1C satellite sensor was made in September 2000. The results of the calibration monitored an attenuation of FY-1C satellite sensor. The new calibration coefficients are important for quantitative application of FY-1C satellite observation data.