真实海洋表面的太阳耀光偏振辐射特性仿真与分析

Simulation and Analysis of Polarization Characteristics for Real Sea Surface Sunglint

由于镜面反射的原因,海洋表面呈现反射强烈的太阳耀光。水体本身属于低反射率的暗目标,太阳耀光成为水体航空航天遥感图像中的噪声;太阳耀光具有强偏振的特点,经过计算可以作为评价在轨传感器偏振指标的替代定标标准光源;也可以用来计算气体成分或者反演气溶胶参数。无论是去除噪声还是获取标准光源,都需要精确计算其辐射特性物理参数。文章首先采用Cox&Munk模型建立真实海洋表面的三维场景,根据考虑偏振的菲涅尔反射定律,推导了太阳耀光偏振辐射模型,并分析了天顶角、太阳-观测相对方位角、风速、风向等参数对反射率及偏振度的影响规律。通过太阳耀光偏振辐射特性分析为偏振定量遥感中计算太阳耀光相关参数提供了理论基础。

The sea surface sunglint is caused by specular reflectance.Water is a kind of dark target with a very low reflectance,so sunglint becomes a big noise in the aerial or aerospace remote sensing images;sunglint is strongly polarized,and can be a natural standard light source for polarized sensor in-flight calibration;sunglint also can be utilized to retrieve gaseous constituents and aerosol properties.For both de-noising and being standard light source,the radiative physic parameters should be calculated accurately.First,A 3-D sea surface model was constituted according to the Cox Munk model;Second,the polarized radiative model of sunglint was deduced based on the 3-D sea surface model and polarized Fresnel reflectance law;Third,the sensitivities of solar-viewing relative azimuth,zenith,wind speed and wind direction were analyzed utilizing the polarized radiative model.The polarization characteristics analysis of sunglint provides a theoretical basis for the quantitative remote sensing retrievals which uses sunglint.