SPATIAL AND TEMPORAL CHANGES OF AEROSOL IN YANGTZE RIVER DELTA AND ITS METEOROLOGICAL INTERPRETATION

Based on MODIS aerosol optical depth(AOD) data and meteorological observed data from 2008 to 2017, the spatial and temporal distribution of AOD in the Yangtze River Delta area was summarized, which was then explained by analyzing the correlation between AOD and meteorological factors. The results showed that: 1) the annual average AOD fluctuated periodically, which showed its peak value of 0.83 in 2011, and declined rapidly from 2014, with an obvious decrease of 22.8% in 2017 compared with 2014. In addition, the peak value of monthly mean AOD appeared in summer, which was mainly caused by the diffusion of large amount of sea salt aerosol particles and water vapor from the ocean in summer; 2) in terms of spatial distribution, the AOD high value in Yangtze River Delta mainly distributed in southern Jiangsu and Xuzhou area, and the area with AOD high value had gradually narrowed since 2014; the AOD of Zhejiang Province was significantly lower than the other areas, which was closely related to the high topography of Zhejiang Province; 3) the change of AOD had a good positive correlation with the temperature and relative humidity, but the correlation with wind speed was poor and complex, which may be affected by the uncertainty of wind direction. In summer, due to high temperature and humidity, most areas showed high AOD values, and the low temperature and air moisture content in winter caused low AOD. However, the contribution of solid particles to AOD was large in winter, so the change of AOD may reflect the air pollution in winter. The results can provide a reference for aerosol assessment, air quality attribution analysis and air quality improvement in the Yangtze River Delta in future.