基于超光谱比值辐射仪的卫星自动化场地定标与分析

Automatic Field Calibration and Analysis of Satellite Based on Hyper-Spectral Ratio Radiometer

针对我国光学遥感卫星高频次和高精度定标的技术需求,以及目前人工方式进行定标的不足,调研国内外卫星定标的发展现状,研制了超光谱比值辐射仪自动化定标系统,并开展了卫星传感器自动化定标的试验。根据场地定标中的参数需求与自动化定标的目标,比值辐射仪设计积分球测量光谱总照度,并通过遮挡的方式实现了光谱漫照度测量,获得卫星定标中的漫总比数据;同时,辐射仪利用光学镜头的方式实现地面辐亮度测量,实现了大气-地表辐射特性的自动观测,同时仪器集成了定标数据实时预处理和远程传送等功能。在2015年敦煌辐射校正场试验中,辐射仪得到了理想的应用效果并获得了大气光学参数、地表反射率的数据,为卫星传感器的定标提供了数据支持。经过与传统测量仪器的对比,地表反射率的相对偏差在0.5%~1.5%,大气参数中光谱辐照度的绝对偏差小于5%,漫总比的绝对偏差不大于0.015%。采用辐照度基法利用测量的数据对Aqua MODIS光学遥感器的通道1~5进行了场地定标,通道1~4的对比相对偏差小于1%,通道5的偏差结果为7.24%,验证结果满足了卫星传感器自动化定标的初步需求。

With the demand of calibration technology of high frequency and high precision in terms of the optical remote sensing satellite of China,and the deficiency of the artificial work,the automatic system of hyper-spectral ratio radiometer was developed by investigation the calibration situation of domestic and abroad satellite,then the automatic calibration of satellite sensor was carried out.According to the parameters demand of field calibration and the goal of automation,the ratio radiometer was designed to measure global spectral irradiance by integrating sphere,and the diffuse spectral irradiance was measure by the shelter,so the diffuse-global ratio was calculated by these data.Simultaneity the ground radiation was measured with radiometer opticallens and the automatic observation of atmospheric and surface radiation characteristics was achieved,In addition,the data preprocessing of real-time and remote transmission were integrated in the system.With the field test on the Dunhuang radiometric calibration sites in 2015,the radiometer worked in an ideal way,and the atmospheric optical parameters and surface reflectance data were acquired,which support the calibration of satellite sensor.The comparison with the traditional measurement was carried,the relative deviation of the surface reflectance is less than 5%,and the absolute deviation of the atmospheric parameters is less than 5% and the diffuse ratio is less than 0.015%.According to the measured data and based on irradiance-based method,the field calibration applied to the band 1~5of Aqua MODIS,the relative deviation of band 1~4is less than 1% while the band57.24%,so the requirement of the automatic calibration of the satellite sensor was satisfied preliminarily.