海洋背景下气溶胶的偏振光散射特性研究

Study on Polarized Light Scattering by Aerosol over Ocean

基于矢量辐射传输理论,利用矩阵算法研究了海洋-大气耦合系统中,海雾气溶胶对太阳光的偏振散射特性。整个大气层垂直方向分为若干平面平行层,考虑了大气分子、云层以及气溶胶的垂直分布;海洋表面按照风驱随机粗糙海面进行了分析,考虑了海洋波斜率分布和遮蔽效应;海洋体也由若干平面平行层构成,考虑了海水以及叶绿素的吸收和散射影响。大气和海洋体每层的反射矩阵和透射矩阵以及源函数由离散坐标方法计算,整个海-气系统的散射特性由矩阵方法通过耦合层与层之间相互辐射得到。研究了整个海-气系统反射的太阳辐射以及偏振度对太阳光的波长、入射天顶角、观测角度、海洋表面风速、云和气溶胶的光学厚度,以及气体吸收等的敏感性。计算结果表明,多波长多角度偏振度信息随海洋表面和大气环境变化敏感,可以结合辐射强度和偏振度对海洋背景下气溶胶特性进行遥感反演。

Based on the radiative transfer theory, the polarized light scattering characteristics of sea spray in an atmosphere-ocean system by sunlight is studied based on the matrix operator method. The whole atmosphere layer is divided into many sub-layers in the vertical direction, and the vertical distributions of the atmosphere molecular,clouds and aerosol are considered. The ocean surface is dealt as the wind-generated rough ocean surface, and the wave slope distribution and the shadowing effect of the ocean wave are considered. The ocean body is divided into many plane parallel sub-layers, and the absorption and scattering characteristics of sea water and the chlorophyll are considered by an empirical model. The reflection and transmission matrices and source vectors are obtained for each atmospheric or oceanic layer though the discrete ordinate solution. The scattering characteristics of the whole atmosphere- ocean system are constructed using the matrix operated method, which combines the radiative interaction between the layers. The sensitivity studies for the reflected solar radiation by the whole atmosphere-ocean system are conducted for various solar wavelength, incidence solar zenith angle, observation angle, ocean-surface wind speed, the optical thickness of the clouds and aerosols, and the absorption of the gas. The simulation results show that the multi- wavelength and multi- angular polarization information are sensitive to the varies of the atmosphere and ocean surface conditions. The reflected solar radiative intensity and the polarization degree can be combined to retrieve the aerosol information.