| Atmospheric aerosol is a suspension system of liquid or solid particles in the air.The particle matter with aerodynamics directly smaller than 2.5?m is called PM2.5.Using aerosol optical properties retrieved based on ground-based and satellite remote sensing data to estimate the near-surface PM2.5 mass concentration is a new and effective way to monitor regional air quality.In this paper,MODIS Level 2 aerosol products,aerosol size distribution of AERONET and FY3D MERSI Level 1 data were used to estimate the near-surface PM2.5 mass concentration,respectively.The main research contents and results are as follows:?1?Based on the aerosol optical depth of MODIS Level 2 product for morning and afternoon respectively,the PM2.5 concentration near the ground in the northern suburb of Nanjing was obtained by this method.The results were evaluated by the data of the particle concentration of the ground site.The results show that the mean value of AOD is 0.46±0.03 in the background of northern suburbs of Nanjing in the winter from 2014 to 2017,and the mean value of PM2.5 is 57±5?g/m3.The PM2.5 estimated by the new method is in good agreement with the observed data and the trend is basically the same.In addition,the correlation of PM2.5and meteorological elements is obvious.r,MAPE and RMSE for hourly mean AOD are 0.69,52and 26.58?g/m3,respectively.;r,MAPE and RMSE for daily mean AOD were 0.71,39 and23.43?g/m3,respectively.In addition,accuracy of MYD is slightly higher than that of MOD.?2?Based on the aerosol size distribution of Beijing,Xianghe,Xuzhou and Taihu sites in Aerosol Robotic Network?AERONRT?from 2016 to 2017 to estimate the near-surface PM2.5concentration.After corrections of aerosol layer height and relative humidity,the estimated results are evaluated by ground monitor data.They show that:The R2 of the estimated and observed daily averaged PM2.5 concentration at the near-ground surface from 2016 to 2017 is0.42 for Beijing,0.31 for Xianghe,0.05 for Xuzhou and 0.49 for Taihu.After corrections of aerosol layer height and relative humidity,R2 values increase to 0.69?RMSE=39.33?g/m3?,0.79?RMSE=35.36?g/m3?,0.49?RMSE=32.93?g/m3?and 0.75?RMSE=15.24?g/m3?,respectively;Comparison with estimated and observed values of the seasonal average PM2.5 concentration shows that the two are basically close.Based on this method,the annual averaged PM2.5 concentrations in Beijing and Xianghe over 12 years from2006 to 2017 have been estimated and the trend of changes has been analyzed.?3?Based on the MERSI level 1 data,the aerosol optical depth of Beijing-Tianjin-Hebei region in 2018 was retrieved by the dark target method.The retrieval results were verified by the AOD of the ground-based AERONET site.The spatial distribution of AOD in the Beijing-Tianjin-Hebei region was further analyzed.The results show that the retrieval AOD is basically consistent with AERONET AOD.The R2 of Beijing,BeijingCAMS,BeijingPKU,BeijingRADI and Xianghe is 0.85?RMSE=0.196?,0.87?RMSE=0.194?,0.84?RMSE=0.197?,0.85?RMSE=0.183?and 0.90?RMSE=0.181?,respectively.Furthermore,the retrieval results were compared with MYD043K AOD.It was found that the retrieval AOD of MERSI was better than MYD043K AOD and the MODIS results are larger.The AOD spatial distribution map of MERSI retrieved in Beijing-Tianjin-Hebei region is basically the same as MODIS,with higher in the south and lower in the north.There is a clear demarcation zone,but the effective sample points of the MERSI inversion result are smaller than MODIS. |
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