[Spatio-Temporal Distribution and Variation Characteristics of Aerosol Optical Properties in Henan Province]

The temporal variation and spatial distribution characteristics of aerosol optical depth (AOD), aerosol column mass concentration (AMC), and fine mode fraction (FMF) were analyzed based on the aerosol product information obtained from MODIS/Terra C6.1 from 2001 to 2018 in the Henan province. The spatial distribution of AOD and AMC in all seasons are high in the east and low in the west, and high in the north and low in the south, which was related to the special topography, population distribution, and number of enterprises in each region. Meanwhile, the spatial distribution of FMF is opposite to that of AOD and AMC. In spring, AMC was the highest, while FMF was the lowest, indicating that it was mainly affected by dust aerosol in spring. AOD and FMF were the highest in summer, while the AMC was lower, mainly because the high values of AOD in summer were caused by the hygroscopic growth of aerosol. The increase of rainwater scouring and secondary aerosol generation led to the domination of fine-mode aerosols in summer. In autumn and winter, the AOD and AMC were relatively low, and the FMF was slightly higher than in spring. The AOD and AMC in the Henan Province showed a decreasing annual trend, while the FMF exhibited an increasing trend. The average monthly peak-valley difference of AOD, AMC, and FMF decreased after 2011.