Simulation Of Ultraviolet Polarized Remote Sensing Based On The Typical Aerosol Modeling In China

With the development of space sensors,it has the higher requirements on the dimension of detection target information.So ultraviolet(UV)polarization has become a development trend.Due to the complexity of aerosol composition and the diversity of the structure and life cycle,it is difficult to directly quantify the aerosol parameters.However,in the vector radiation transfer equation,the effect of aerosols on the light transmission cannot be ignored.Therefore,the typical aerosol models are the basis for improving the UV polarized radiation transfer model,which could not only provide the help for target detection and climate impact,but also promote the development of multidimensional remote sensing sensors.In this study,we used the vector radiative transfer equation to analyze the sensitivity of the parameters of aerosol model.Next,we taked the ground-based observation data in China for a long time to obtain the typical aerosol models.Finally,based on the typical aerosol models in China,the atmospheric UV polarized remote sensing simulation were analyzed and verified.The main conclusions are as follows:Optical sensitivity analysis of aerosol model has been carried out.Under different observation angles,the sensitivity of aerosol model parameters has been analyzed.Stokes parameters and the Degree of Linear Polarization(DOLP)are more sensitive on the fine-mode effective radius and effective volume than those of the coarse mode.The sensitivities of Stokes to the fine-mode effective radius and effective volume are all in the magnitude of 10^-2,and those for the coarse mode are ranged from 10^-3 to 10^-4;The sensitivities of DOLP to the fine effective radius and effective volume are in the range of 10^-1and 10^-2,respectively,and that to the coarse mode are both in the range of 10^-2.The magnitude of the sensitivities of Stokes to the real part of complex refractive index(CRI)is between 10^-2 to 10^-3,and that of the sensitivity of DOLP is in the range of 10^-2.Moreover,the sensitivity range of Stokes parameter I to the coarse-mode imaginary part of CRI is larger than the fine mode,but the magnitudes of both fine and coarse mode are in the range of10^-1 and those of the parameter Q and U are in the magnitude of 10^-2.DOLP has the sensitivity magnitude of larger than 1 to the coarse-mode imaginary part.The spatial characteristics of aerosols and the typical aerosol models in China have been analyzed based on the long time ground-based observation.The aerosols are mainly divided into five categories:Dust,Heavy Pollution,Urban Pollution,Rural and Absorption.Moreover,the maritime aerosol models of Taiping and Dongsha in different seasons have been analyzed to represent the south and north of the South China Sea,respectively,which employed the seasonal average aerosol parameters that simple averaging of all retrievals and all wavelengths.Finally,the key parameters and database settings of the UV polarized simulation system are introduced.Based on the typical aerosol models and POLDER observation data in China,the UV polarized remote sensing simulation test is carried out to confirm the reliability of the simulation system.In this study,the correlation coefficients of the scalar and polarized reflectances between the simulation and observation are 0.88 and 0.93,respectively.The slopes of fitted lines of the scalar and polarized reflectance are 0.68 and 1.01 and the both intercepts are close to 0.The system error of the scalar reflectance is due to the influence of the surface model,while the simulation results of polarized reflectance are better.It can be seen that under the specific observation Angle of ultraviolet band,the seasonal averages of scalar reflectance have the higher value in autumn and winter(0.28 and 0.29),while that in summer and autumn is lower(both 0.25).However,the polarization reflectance reached the highest in summer and autumn(0.124 and 0.123)and that is slightly lower in winter and spring(0.122 and 0.119).The seasonal differences of ultraviolet polarized observation are not only related to aerosol pollution and surface model but also the observation angle and Rayleigh Scattering.