| The atmospheric environmental impact caused by aerosols is widely concerned in the world.The characteristic of large space scale of satellite remote sensing technology makes it an effective means to monitor aerosols.At present,the satellite remote sensing technology is mainly through the retrieval of aerosol optical parameters to gain quantitative description of aerosols.Many satellite platforms have achieved the retrieval of aerosol optical depth,but only using this parameter cannot meet the demand of application in the field of the atmospheric environment.The multi-angle intensity and polarization observation represented by POLDER sensor can obtain more aerosol information,which is the development direction of aerosol satellite remote sensing in the future.Based on POLDER multi-angle intensity and polarization data,the retrieval of aerosol optical parameters is studied in this paper.This study puts forward a new framework for aerosol optical parameters retrieval,the intensity and polarization observations are used to obtain total aerosol optical depth and fine-mode optical depth,respectively.And then the aerosol fine-mode fraction is the ratio of the two parameters.This study introduces the empirical orthogonal function to solve the problem of the estimation of surface reflection in the POLDER multi-angle intensity observation for total aerosol optical depth retrieval,and this method has the characteristics of not restricted by the type of surface.In addition,a new method for evaluating the fine-mode optical depth is proposed in this paper,which effectively improves the retrieval accuracy of the optical thickness of fine particles.This study compared the retrieval results with the AERONET ground-based data.The results show that the three aerosol optical parameters obtained in this study are consistent with the ground-based observation data.The correlation coefficients(r)of the three retrieved parameters are 0.898,0.921,and 0.759,respectively.The mean absolute errors(MAEs)are 0.111,0.083,and 0.140,respectively.The root mean square errors(RMSEs)are 0.151,0.115,and 0.171,respectively.The percentage of the results in the expected error range(Gfrac)are 74.83%,70.19%,and 71.88%,respectively.Under the condition of bright surface in winter,the r between the retrieved total aerosol optical depth results and the ground-based data is 0.901,the Mae is 0.104,the RMSE is 0.138,71.96% of the results are falling within the expected error.For the case of high aerosol loading,the comparison of the retrieved fine-mode aerosol optical depth and LOA(Laboratoire d'Optique Atmospherique)product with the ground-based data shows that the r increased from 0.499 to 0.881,the MAE reduced from 0.119 to 0.119,the RMSE reduced from 0.142 to 0.056,the Gfrac increased from 32.43% to 91.89%.The comparison of the retrieved fine-mode fraction and the MODIS product shows that the r increased from 0.595 to 0.859,the MAE reduced from 0.363 to 0.363,the RMSE reduced from 0.432 to 0.137,the Gfrac increased from 22.08% to 81.81%.Based on the aerosol optical parameters retrieval framework proposed in this study,an aerosol optical parameters retrieval system was developed based on the IDL language,and the time and space distribution characteristics of aerosol optical parameters in China were obtained by this system.The results indicate that the north China plain,Yangtze river delta,pearl river delta,Sichuan and Chongqing economic zone,north xinjiang,southern xinjiang,and part of Inner Mongolia have the high value of total aerosol optical depth.The north China plain,Yangtze river delta,pearl river delta,and Sichuan and Chongqing economic zone are the high value regions of the aerosol fine-mode optical depth and fine-mode fraction.Further analysis using the longtime series data of the typical regions in China shows that the aerosol fine-mode fraction increases year by year in the north China plain,Yangtze river delta,pearl river delta,and Sichuan and Chongqing economic zone,and they reached the highest in winter. |
PDF Full Text Request