东亚夏季风环流对气溶胶分布的影响

用2001—2012年逐月的MODIS-TERRA卫星观测气溶胶光学厚度(AOD)资料和NCEP/NCAR风场资料,分析了5—8月东亚地区AOD的时-空分布特征,研究东亚夏季风环流对气溶胶时-空分布的影响。主要结论如下:5—8月的中国东部及邻近海洋上AOD有着显著的季节演变特征,尤其是32.5 °N附近的AOD高值区,其强度和范围在5—8月逐渐增强然后又减弱。东亚夏季风通过环流输送作用对各地的AOD产生了不同程度的影响,使中国南部AOD减少,而华北和东北地区AOD增加。在强、弱季风年背景下,7月观测的AOD差异与环流输送作用差异的分布特征有着一定的相似性,体现出东亚夏季风年际变化对气溶胶分布的影响。在东亚夏季风演变的不同阶段,季风环流对气溶胶输送大部分情况下,可解释局地气溶胶变化10%~20%的方差。

Impacts of East Asian summer monsoon circulation on aerosol distribution

By using the monthly MODIS-TERRA aerosol optical depth(AOD) product data at 550nm wave length during 2001-2012 and NCEP/NCAR reanalysis data, the temporal and spatial distribution of AOD in East Asia during May to August was analyzed and the impacts of East Asian summer monsoon (EASM) circulation on aerosol distributions were discussed. Four main conclusions are evident: firstly, AOD has significant seasonal variations characteristics from May to August in East China and its adjacent seas, especially in areas near 32.5 °N with high aerosol concentrations. The magnitude and scope of AOD gradually increase and spread, and then decrease and retreat from May to August; secondly, the EASM has a measurable influence on AOD distribution at various degrees through its circulation transportation, which makes AOD decrease in South China but increase in North and Northeast China; thirdly, under the background of extreme strong and weak EASM year, the spatial distributions of the differences of measured AOD is similar to the role of monsoon circulation transportation in July, which reflects the influence of monsoon circulation interannual variability of the EASM on aerosol distribution; finally, the aerosol transportation due to monsoon circulation accounts for the 10%-20% variance of local aerosol changes during the evolution of EASM.