Figure 1

Scatter plots of the AODs derived from CALIPSO, MODIS, and sun photometer with change of PM2.5 from November 2013 to December 2017. (a) CALIPSO vs. sun photometer; (b) MODIS-DB vs. sun photometer; (c) MODIS-DT vs. sun photometer; (d) frequency distribution of AODs. Color bars represent the mass concentration of PM2.5.