[Temporal-Spatial Characteristics and Variability in Aerosol Optical Depth over China During 2001-2017]

Based on the latest monthly data of moderate resolution imaging spectroradiometer (MODIS)/Terra C6.1 aerosol optical depth (AOD), the temporal-spatial distribution and variability trend in AOD over China during 2001-2017 are analyzed to explore the distribution and variation characteristics of AOD in China. Regarding the spatial characteristics, the first prominent high-value center of the annual mean AOD was located in the industrially and economically developed areas of the North China Plain, Central China, the Yangtze River Delta region, the Pearl River Delta region, and the Sichuan Basin. The second prominent high-value center of the annual mean AOD was located in the dust aerosol-dominated areas of Taklimakan Desert. Two low-value centers of the annual mean AOD were located in the eastern part of Inner Mongolia to the north of Northeast China and the Tibet Plateau. Regarding the temporal characteristics, the AOD value peaked in eight areas in spring and summer. The annual mean AOD values in the Taklimakan Desert, Sichuan Basin, and Pearl River Delta peaked from March to May, and those in the North China Plain, Central China, and Yangtze River Delta peaked from May to July. The trend characteristics showed that during 2001-2006, the AOD in Northwest China and Inner Mongolia showed a downtrend, and that in the east-central China and the eastern part of southwest China showed a growth trend. During 2007-2012, the trend of AOD in the Tibetan Plateau and the Taklimakan Desert changed from decreasing to increasing. The growth trend of AOD in the North China Plain and the Sichuan Basin was weakened, and the AOD in the Yangtze River Delta showed a weak downward trend. During 2013-2017, the AOD in most areas of China showed a significant downward trend.