中文摘要：

利用2000年3月至2009年2月MODIS遥感气溶胶光学厚度（AOD）产品，分析并对比了我国中、东部的华北、四川盆地、长江三角洲和珠江三角洲4个地区AOD的季节分布及其变化。发现这9年各地区平均AOD呈显著增长趋势，除四川盆地秋季有下降外，其他各个地区各个季节均有上升趋势。长江三角洲具有最大的年平均和季节平均AOD，年平均增长率高达1．82％；四川盆地次之；华北和珠江三角洲较小。4个地区AOD的季节分布及变化特点有共性又各有不同。总体看来，夏季AOD增长最快，夏季与春季的差距在变小，其中华北地区夏季一般高于春季；冬季AOD最小，增长也最慢，与其他季节的差距在增大。一些地区的部分季节，如华北地区的夏、秋季，四川盆地的春、夏、秋季，珠江三角洲的秋季，在2006--2008年有明显的连续下降趋势。这些结果有助于这些地区的区域气候变化研究和空气质量研究。

英文摘要：

Seasonal changes of aerosol optical depth over the Central and Eastern China, the Sichuan Basin, the Yangtze River Delta and the Pearl River Delta from MODIS data from March 2000 to February 2009 are analyzed and compared. It is found that in the 9 years the mean AOD over every region in all seasons has significant increasing trends, except for Sichuan Basin in autumn. The highest AOD occurs over the Yangtze River Delta in both annual and seasonal averages, and the increasing rate of annual mean is up to 1.82% per year. The AOD over Sichuan basin ranks second, and then is North China, the Pearl River Delta has the lowest annual average AOD. The fastest increase of AOD is in summer, the difference between spring and summer becomes smaller, and some areas, such as North China, AOD in summer is higher than that in spring. AOD data are the least and their growth rate are the lowest in winter. Thus, the gap between winter and other seasons becomes larger. The AOD over some regions in some seasons, such as over the North China in summer and autumn, the Sichuan Basin in spring, summer and autumn, and the Pear River Delta in autumn, over the period of 2006 to 2008 have continuous decreasing trends. These results will benefit the studies of regional climate change and air pollution variation.