Simultaneously Retrieving Aerosol Optical Depth and Surface Albedo over Land from POLDER''''s Multi-angle Polarized Measurements I: Theory and Simulations
利用多角度POLDER偏振资料实现陆地上空大气气溶胶光学厚度和地表反照率的同时反演 I. 理论与模拟

The remote sensing of aerosol optical thickness and surface albedo has long been a challenge in the earth observation since both the atmosphere and surface contribute to the space-borne measurements,and they are difficult to be separated from the measurements,especially over land where radiances from the surface reflectance and atmospheric scattering are comparable. The satellite measured inteosities are sensitive to both atmospheric scattering and surface albedo,while polarized radiances are only sensitive to the atmospheric scattering.Based on this principle,the aerosol optical parameters are first given through look-up table method,and then they are corrected with the total intensity measurements.The POLDER(POLarization and Directionality of Earth Reflectance) multi-angle polarized measurements are simulated and then used in retrieval simulations,results show large errors for aerosol optical parameters if only polarized measurements are used in retrieval algorithm,especially for short wavelength channel of 670 nm,in which multiple scattering effect is relatively strong.The results can be improved if intensities are also be used,and meanwhile surface albedo over land can be given.The statistics show that the correlation coefficients between the retrieved and simulated values,both for aerosol optical depth and surface albedo,are above 0.99.New semi-parameterized look-up tables are also established to speed up the efficiency of retrieval algorithm.