大气折射对光学卫星遥感影像几何定位的影响分析

摘要

采用 ISO国际标准大气模型和 Owens大气折射系数算法，根据大气层内不同纬度和海拔高度处的大气折射系数分布规律，把地球大气简化为对流层和同温层的双层均匀球形大气，从在轨光学卫星CCD探元视线出发，使用视线跟踪几何算法，计算不同侧视角下大气折射产生的几何位置偏差.结果表明，大气折射几何偏差随卫星观测角的增加而非线性迅速增加.当卫星运行在650 km 的太阳同步轨道，侧视30°成像时，大气折射产生约2．5 m 的几何偏差；卫星侧视45°成像时，大气折射产生约9 m 的几何偏差.在高分辨率敏捷卫星成像和宽视场卫星遥感图像的严密几何定位处理中，使用本文提出的大气折射几何偏差算法和严密几何定位大气折射校正模型，在地心地固坐标系下补偿严密几何模型中存在的大气折射偏差，能够进一步提升高分辨率卫星遥感图像的无控几何定位精度，应用于我国高分系列卫星遥感图像地面几何定位处理.%The collinear rigorous geometric model contains the atmosphere refraction geometric error in off-nadir observation.In order to estimate and correct the atmosphere refraction geometric error,the ISO international standard atmospheric model and Owens atmosphere refractive index algorithm are applied to calculate the index of atmosphere refraction in different latitude and altitude.The paper uses the weighted mean algorithm to reduce the eight layers ISO standard atmospheric model into a simple troposphere and stratosphere two layers spherical atmosphere.And the LOS vector track geometric algorithm is used to estimate the atmosphere refraction geometric error in different observation off-nadir angle.The results show that the atmosphere refraction will introduce about 2.5 m or 9 m geometric displacement in 30 or 45 degree off-nadir angle individual.Therefore,during geo-location processing of agile platform and extra wide high spatial resolution imagery,there is need to take into account the influence of atmosphere refraction and correct the atmosphere refraction geometric error to enhance the geo-location precision without GCPs.