Polarization Imaging And Cloud Polarization Characteristics Research

The light polarization properties is one of the intrinsic properties of light,the polarization information contains the observation object's physical state.Polarization observation increase the amount of target information,and its features of target identification ability have bigger promotion,at the same time,the polarization signal on the microphysical parameters are sensitive to the polarization data,such as particle size,shape.The application of polarization in the study of cloud and aerosol particles play an important role.French CNES POLDER series satellites provide the polarization observation data for many years,the task was completed in 2013..China is about to launch a GF-5 satellite,it will carry on atmospheric aerosol multi-angle polarization detectors(DPC).It will be China's first satellite-borne detector with polarization angles observation ability.Conducted polarization imaging studies,this paper studied the parameters involved in the process of polarization imaging,and polarization images under different conditions.Finally,the polarization characteristics of scattering theory was used to study the clouds.Establishing polarization imaging model is the key to polarization remote sensing imaging,because of the vector characteristics of radiative transfer,this article first obtains from the vector radiative transfer equation,respectively,on the surface and atmosphere,aerosol parameters were studied.Combined with the earth's surface,atmosphere,aerosol model,using the vector radiative transfer equation,according to the imaging geometry conditions to calculate the polarization component,finally converting into total reflectance and polarized reflectance.After compared with the results in 6sv model,the model is verified by the calculation accuracy under simple aerosol mode.Using the PARASOL inversion products,including land and aerosol parameters to simulate the PARASOL data and compared with the measured data,it verified the validity of the model.Based on the established polarization imaging model,under the complex atmospheric conditions of polarization imaging are discussed.Simulating the ash haze pollution intensity of the radiation intensity and polarization and use the gray frequency diagram legal quantitative study the image characteristics,compared with clear sky imaging,the result shows : under the condition of the ash haze aerosol pollution of polarization imaging can reflect the ash haze of radiation and the radiation of the polarization of aerosol well.Combined with the grey haze aerosol polarization imaging to study the ash haze polarization characteristics of aerosols,polarized radiation on the ash haze aerosol particles are discussed,including the complex refractive index,optical thickness and the sensitivity of the particle distribution.Polarization imaging parameters of water and ice clouds are obtained,including particle distribution,the complex refractive index of water and ice,particle size range,etc.Simulated images under the water cloud cover,its accuracy is verified by an PARASOL measured data,the results show that the simulation precision of cumulus clouds in the sky over the land is high.Using Mie and T-scattering matrix theory to calculate the scattering characteristics of ice clouds particles.To simulate the different shapes of ice crystal particles cirrus clouds,it is concluded that six prism shape particles that axial length is 100 um,side length is 12.5um coincides with the field observing value very well.Based on the polarization properties of the pollution and clean cumulus clouds over the land,a new algorithm was provided to distinguish the pollution and clean cumulus over land.Analyzed the effects of the type of surface,cloud optical thickness for the algorithm.Using the PARASOL Level-2 cloud product data to verifies the algorithm,the results show that using the proposed algorithm can distinguish between pollution and clean cumulus clouds over the land well.