基于洋面场景的MERSI偏振辐射特性反演及其分析方法

Retrieval and Analysis of MERSI Polarization Radiation Characteristics Based on Ocean Scene

辐射传递链路的偏振灵敏度会影响中分辨率光谱成像仪(MERSI)遥感观测数据的精度及其后续应用,故需要对其偏振灵敏度进行反演、分析及定量去除以提高辐射定标的精度。针对在轨后的MERSI,选择洋面场景这一偏振度较大的区域,通过对卫星观测数据和环境数据进行预处理,基于海洋表面三维波浪斜坡的概率密度模型和菲涅耳反射定律来描述海表辐射状态,利用6SV辐射传输模拟工具来分析大气对偏振辐射状态的影响,将其与海表辐射状态耦合可得到大气顶偏振辐射状态,实现了对MERSI偏振辐射特性的反演。实验分析了MERSI在特定波段的偏振辐射特性,发现其偏振度随着卫星天顶角的变化呈现不对称分布,反射率误差随着卫星天顶角及偏振度的变化基本比较稳定;分析了MERSI在不同观测几何、风速风向下偏振敏感性的变化规律。

The polarization sensitivity of the radiative transfer link will affect the accuracy and subsequent application of the remote sensing data of the medium resolution spectral imager(MERSI),so it is necessary to invert,analyze,and quantitatively remove the polarization sensitivity to improve the accuracy of radiometric calibration.Aiming at the MERSI in orbit,the region with large polarization degree of ocean scene is selected.Through the preprocessing of satellite observation data and environmental data,the sea surface radiation state is described based on the probability density model of ocean surface three\dimensional wave slope and Fresnel reflection law.6SV radiative transfer simulation tool is used to analyze the influence of atmosphere on polarized radiation state.By coupling it with the sea surface radiation state,the atmospheric top polarized radiation state can be obtained,and the inversion of the polarized radiation characteristics of MERSI can be realized.The polarization radiation characteristics of MERSI in specific wave band are analyzed experimentally,and it is found that the polarization degree of MERSI is asymmetrically distributed with the change of satellite zenith angle,and the reflectivity error is stable with the change of satellite zenith angle and polarization degree.The variation law of polarization sensitivity of MERSI under different observation geometry and wind direction is analyzed.