Research On The Ability Of Spaceborne Multi-angle-multi-spectral-multi-polarization Imager To Retrieve Cloud Characteristics

Meteorological satellites are playing an important role in the monitoring of earth-atmosphere system.Among them,the satellite-based multi-angle,-spectral and-polarization imager can obtain more solar radiation information and can be used for accurate remote sensing of atmospheric parameters.However,there are some new problems with multi-angle,-spectral and-polarization observations.For example,for cloud properties,how to design multi-angle,-spectral and-polarization imagers,whether the information can be used to improve the ability of cloud detections and property retrievals,and so on.Considering cloud phase,optical and microphysical properties(e.g.,cloud optical thickness COT,particle effective radius Re,aspect ratio AR and surface roughness level σ),this study systematically discusses the ability of multi-angle,-spectral,and-polarization observations on cloud property retrievals by performing the polarized radiation transmission theory and the theoretical information content(IC)analysis.To verify the results of theoretical analysis,the satellite-based POLDER data are used to carry out the experimental researches.The result shows that multi-angle polarization observations can be applied to optimize the identification of cloud phase.And,the IC of cloud properties can be improved with the additional information from multi-angle,-spectral and-polarization observations.The combination of the radiance intensity information at the 0.87,1.24,1.64 and 2.13μm channels and polarization information at the 0.87 and 2.13μm channels at three observation angles,which correspond to the scattering angles in the range of 100°-130°,130°-140°,and 140°-160°,is helpful to maximize the obtained information content of cloud properties.Besides,retrieval of Re exhibits larger uncertainties,and the use of multi-angle,-spectral and-polarization observations can effectively reduce the uncertainty and improve its retrieval result.Finally,based on the POLDER observations,some theoretical conclusions are verified with case studies.The conduct of this study is benefit to the future design and data application of the multi-angle polarization imagers,and provides reference for the development and improvement of cloud property retrieval algorithms.