Abstract:
In this study, the aerosol optical depth (AOD) products of the FY-4A satellite are evaluated base on the satellite data, gridded distribution of near surface PM
2.5 mass concentration in China is retrieved using the improved PMRS method. The results show that the FY-4A satellite retrieved AOD and AERONET observations agree well at various sites, although there exist certain underestimates or overestimates. The correlation ranges from 0.54 to 0.87. FMF is divided by the criterion of 0.4. When FMF>0.4, the fitting results are closer to the observations of AERONET than that when FMF≤0.4; however, when FMF≤0.4, the AOD stability of satellite retrievals is better than that when FMF>0.4. By introducing the size of AOD, the estimation algorithm for VE
f is improved when FMF>0.4. Using the improved PMRS method, hourly retrievals of China near-surface PM
2.5 are better correlated with the surface observation. Among all the results, the correlations between retrievals and observations are higher than 0.7 at Urumqi, Shijiazhuang and Xuzhou. However, there are overestimates or underestimates in the retrievals and the errors are determined by various factors. Regarding the spatial distribution, the national average of near-surface PM
2.5 of satellite retrievals has a good correspondence with the results of near-surface observations in 2019. The monthly variation trends of the two are basically the same, which can basically reflect the spatial distribution of the near-surface PM
2.5 in China. Specifically, in autumn and winter, satellite retrievals over the areas around Beijing-Tianjin-Hebei, the Fen-Wei Plain and other high-pollution areas all correspond well with ground observations.