摘要:气溶胶已是东亚地区最主要的大气污染物之一，其时空分布会受到东亚季风气候的影响。利用2000～2014年MODIS/AOD（Moderate-resolution Imaging Spectroradiometer/Aerosol Optical Depth）和NCEP月平均气象场再分析资料，本研究分析了东亚冬季风长期变化趋势、气溶胶年际变化规律，探讨了东亚冬季风强度变化对气溶胶分布的影响。基于MODIS/AOD，发现近10年东亚地区冬季AOD呈现上升趋势，最大值为2007年的0.44，高值区覆盖四川盆地、华北平原及长江中下游大部分地区。风场特征类冬季风指数分析表明，东亚冬季风存在明显的年际和年代际差异，近年出现逐渐减弱的趋势。强冬季风年，海陆气压差增大、东亚大槽加深增强，东亚地区偏北风异常，风场的增强将引导更多冷空气南下，从而给东亚大部分地区带来明显的降温天气；弱年相反。气象场差异引起气溶胶分布变化，强年较强的偏北风将气溶胶向南方输送，东亚地区AOD出现“北低南高”的空间分布；弱年偏北风较弱，导致气溶胶集中在华北平原一带，AOD出现“北高南低”的空间分布。
关键词:东亚冬季风/
季风指数/
气溶胶/
气溶胶光学厚度（AOD）
Abstract:Aerosol is one of the most significant air pollutants in East Asia. Its temporal and spatial distribution can be affected by the East Asia winter monsoon. Using the Moderate-resolution Imaging Spectroradiometer (MODIS) aerosol product and the National Center for Environmental Prediction (NCEP) reanalysis monthly meteorological field data between 2000 and 2014, this study statistically analyzes the variation trend of the East Asia winter monsoon (EAWM), the annual variation of the aerosol optical depth (AOD) over East Asia, and the effect of the anomalous EAWM on the distribution of aerosols. The analysis based on the aerosol product shows that the AOD values continually increase during the recent decade in the winter of East Asia with a maximum value of 0.44 in 2007. High values usually occur in the Sichuan Basin, the North China Plain, and most areas of the middle and lower reaches of Yangtze. With the aid of the EAWM index defined by the characteristics of the wind field, the EAWM is found to have strong interannual and interdecadal variations and exhibits a gradually decreasing trend. Results also show that the EAWM has a considerable effect on the spatial distribution of aerosols. In strong EAWM years, the stronger north wind can enhance the transportation of aerosols to the southern area and form the spatial distribution pattern of the north low and south high for the AOD over East Asia. However, in weak EAWM years, the transportation effect is weakened, resulting in the accumulation of more aerosols in the North China Plain and the formation of the AOD pattern of the north high and south low.
Key words:East Asia winter monsoon/
East Asia winter monsoon index/
Aerosol/
Aerosol optical depth (AOD)
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