交叉定标中的不确定度分析及定标系数计算改进  

Uncertainty analysis in cross-calibration and optimization calculation of calibration coefficients

作　　者：高帅 李元 白廷柱[1] 张玉香[2] 郑小兵[3] GAO Shuai;LI Yuan;BAI Ting-zhu;ZHANG Yu-xiang;ZHENG Xiao-bing(School of Optics and Photonics,Beijing Institute of Technology,Beijing 100081,China;Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites,National Satellite Meteorological Centre,China Meteorological Administration,Beijing 100081,China;Key Laboratory of Optical Calibration and Characterization,Anhui Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Hefei 230031,China)

机构地区：[1]北京理工大学光电学院,北京100081 [2]中国气象局国家卫星气象中心中国遥感卫星辐射测量和定标重点开放实验室,北京100081 [3]中国科学院安徽光学精密仪器研究所通用光学定标与表征技术重点实验室,安徽合肥230031

出　　处：《中国光学》2020年第3期568-576,共9页Chinese Optics

基　　金：国家重点研发计划课题(No.2018YFB0504601);国家自然科学基金资助项目(No.41271373)。

摘　　要：一般交叉定标方法是利用普通最小二乘法的回归方式对时间、空间、观测几何、光谱匹配得到的近一致观测数据点对来计算定标系数,该方法忽略了各数据点对的质量差异,降低了定标系数的有效性。针对此问题,本文提出了基于不确定度计算的定标改进方法,利用不确定度分析方法计算数据点对中各辐射基准值的不确定度并给出权重系数,采用加权最小二乘法回归定标系数。选取与在研的基准载荷参数最为接近的HYPERION作为辐射基准替代载荷,分别利用普通最小二乘法和加权最小二乘法对MODIS CH1~7进行了定标,采用MODIS官方定标系数作为真值对定标结果进行验证。结果表明,采用加权最小二乘法对MODIS的1、2、4、5、6、7通道回归的定标系数更接近真值,定标结果的最大相对误差与传统方法相比降低了3%~5%,平均相对误差降低了0.5%~1.5%,说明本文的加权最小二乘法可进一步提升交叉定标精度。The general cross-calibration method uses the ordinary least square method to regress the calibra-tion coefficient by data points selected after time,spatial,observation geometrics and spectral collocation.However,the ordinary least square algorithm would reduce the validity of the regressed result because of ignoring the differences in quality between each data point.An optimized method based on the calculation of uncertainty was proposed.This uncertainty analysis method was used to quantify the uncertainty of the radiation standard value for each data point,and their weight factors were calculated.The weighted least square method was used to regress the calibration coefficient.Using HYPERION as a radiance standard,the calibration coefficients of MODIS channels 1 to 7 were each regressed using the ordinary least squares method and the weighted least squares method.The regressed coefficients were compared with the official calibration coefficient.The results show that the calibration coefficients calculated using the weighted least squares method were closer to the official coefficients of MODIS channels 1,2,4,5,6,and 7.The maximum relative error reduced to 3%~5%and the average relative error decreased to 0.5%~1.5%compared with the ordinary least squares method,which indicates that the weighted least squares method proposed in this paper can further improve the calculation accuracy of cross-calibration.

关 键 词：基准载荷 太阳反射波段 交叉定标 加权最小二乘法 不确定度 

分 类 号：TP732[自动化与计算机技术—检测技术与自动化装置]