资源环境科技发展态势分析平台

The spatial-temporal characteristics of aerosol loading over the Yangtze River Basin, China during 2001-2015 were investigated using moderate resolution imaging spectroradiometer (MODIS), multi-angle imaging spectroradiometer (MISR), and ground-level particulate matter (PM) data. Aerosol optical depth (AOD) >0.8 occurs in the Yangtze River Delta, central China, and the Sichuan Basin, while AOD <0.3 occurs over higher-elevation areas in the western Sichuan Plateau and the source regions of the Yangtze River. The western Sichuan Plateau is characterized by fine-mode natural aerosols, while the source region of the Yangtze River is more influenced by dust aerosols. The Sichuan Basin, central China, and the Yangtze River Delta are dominated by anthropogenic aerosols. The spatial distribution of ground-level PM2.5 and its ratio to PM10 confirm the high aerosol loading and dominance of small particles over the middle and lower Yangtze Basin. Over the Yangtze River Delta, central China, and the Sichuan Basin, AOD varies seasonally from low in the cold months to high in the warm months, being suppressed by rainfall and wind during the Asian summer monsoon. Precipitation increases aerosol loading in the western Sichuan Plateau but reduces dust particles in the source region of the Yangtze River. There is no significant AOD trend over most areas of the Yangtze River Basin during 2001-2015, while strong decreasing trends are found over most of the middle and lower Yangtze Basin during 2011-2015. These decreasing trends may relate to changes in annual precipitation, wind speed, and air-pollution control policies. The NO2 and SO2 emissions decreased by 16.51 and 23.40% over major provinces and cities of the Yangtze River Basin from 2011 to 2015. An increase in rainfall over the middle and lower Yangtze Basin and a better pollutant diffusion condition in the Sichuan Basin also favour the decreasing AOD during this period.