中国东部AOD等级变化及与东亚夏季风的联系

利用2000年3月～2017年1月Terra卫星反演的最新版本C06的MODIS气溶胶光学厚度（AOD）、NCEP fnl全球业务分析数据、CMAP降水、CERES SYN1deg Ed4月平均资料、NCEP/NCAR再分析资料等，依据区域平均AOD距平的显著年际变化特征，将历年AOD划分为5个不同的污染等级，并探讨了不同污染等级的局地成因及其与季风环流的联系.结果表明，夏季中国东部地区AOD异常偏大与地面风速小、中高层季风环流系统不利于气溶胶扩散有关.气溶胶污染最重（最轻）时，气溶胶与到达地面的太阳短波辐射、地面气温、风速及降水存在密切联系；在其他污染等级下，除了与到达地面的短波辐射有密切关系外，与其他量的联系并不明显.气溶胶污染严重时，到达地面的太阳短波辐射相对减小，地面气温异常偏低，低层大气冷却，地面风速减小，地面降水呈现南多北少的变化特征；反之，气溶胶污染较轻时，到达地面的太阳短波辐射相对增加，地面气温异常偏高，低层大气加热，地面风速增大，地面降水呈现南少北多的变化特征.

Features of graded AOD in East China in association with East Asian summer monsoon anomalies

Using the data of the latest-released aerosol optical thickness (AOD) (Collection 6) as derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra spacecraft, the Final Operational Global Analysis data (NCEP FNL) from National Centers for Environmental Prediction, Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP), CERES syn1deg Ed4monthly average data, NCEP/National Center for Atmospheric Research (NCAR) reanalysis data from March 2000 to February 2017, we have investigated the features of variations of graded AOD and their related circulation anomalies. As per the interannual variations of AOD averaged over the eastern part of China, the AOD is divided into 5 different levels, which corresponds to 5pollution grades. The results show that the anomalies of AOD in East China are larger when the surface wind speed is weaker together with the unfavorable aerosol diffusion condition of the anomalous monsoon circulation in the middle and high troposphere. When the aerosol pollution is strongest (weakest), variations of AOD is strongly related to the variations of the solar radiation at the earth surface, surface temperature, wind speed, and precipitation. At other AOD levels, the air pollution is significantly related to the surface solar radiation rather than other variables. When the air pollution is severe, the solar radiation at the earth surface is relatively lower, along with the lower surface temperature. The atmosphere in lower troposphere is cooling, and the wind speed is weakening. Meanwhile, the more precipitation occurs in the southern and less in the northern part of the eastern China. On the other hand, when the air pollution is very light, the solar radiation that reaches the earth surface will increase, and the surface air temperature gets higher. At this time, the surface wind will get stronger, and less precipitation will be received in the southern and more in the northern part of East China.