FY-1C遥感器可见近红外各通道在轨辐射定标
IN-FLIGHT VICARIOUS RADIOMETRIC CALIBRATION FOR VIS-NIR CHANNELS OF FY-1C SATELLITE SENSOR AT DUNHUANG SITE
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摘要: 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2000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%,28%,22%,而通道2,6,9,10性能衰减较小(为10%左右)。Abstract: 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 reflect ance-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-1Cs VIS-NIR channels was obtained.By geometric registration of the satellite-ground pixels and a comparison of the mean digital counts with the apparent reflect ance,the calibration coefficients (gain and of fset) from seven channels of FY-1C (center wavelength:455,505,555,630,865,932.5 and 1610nm) were determined.Anerror budget of the reflectance-based calibration method shows that the uncertainty is less than 7%.Comparing the calibration results with the prelaunch calibration,a better agreement at five channels is achieved except the ones in channels 9 (555 nm) and channel 6 (1610nm).Second radiometric calibration of VIS-NIR of FY-1C sat ellite sensor was made in September 2000.The results of the calibration monitored an at tenuation of FY-1C sat ellite sensor.The new calibration coefficients are import ant for quantita-tive application of FY-1C sat ellite observation data.
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