基于卫星资料的华东地区气溶胶三维分布特征研究

利用MODIS和CALIPSO level2气溶胶产品，通过统计分析多个气溶胶光学参数（光学厚度、消光系数、色比和退偏振比）的时空分布及其变化，得出2007~2016年华东地区（27°N~37°N，113°E~123°E）气溶胶三维分布特征.结果表明，华东地区气溶胶光学厚度（AOD）年平均呈现出北高南低，平原高、山地低的分布特征.AOD季节分布表现为春夏高，秋冬低，夏季最高，冬季最低，且研究区域北部（31°N以北）AOD季节变化比南部地区剧烈.气溶胶消光系数（σ）随高度呈指数衰减，秋冬（春夏）低层σ较大（小）但随高度衰减较快（慢），2km以下北高南低.年平均色比（CR）随高度递增，变化范围为0.6~0.7，随时间有减小趋势.CR季节特征为4km以下春季最大，夏季最小且均一；4km以上冬季最大，夏季最小.年平均退偏振比（PDR）随高度递增，变化范围为0.1~0.25，北部较大.PDR季节特征为5km以下春季最大，夏季最小；5km以上冬季最大，夏季最小.从气溶胶组成来看，华东地区2km以下以污染沙尘为主；2~5km春季以沙尘为主，其它季节以烟尘为主；5km以上冬春以沙尘为主，夏秋以烟尘为主.

Characteristics of three-dimensional aerosol distribution in Eastern China based on satellite data

Using MODIS and CALIPSO level2 aerosol products, the 3D variation characteristics of multiple aerosol optical parameters (aerosol optical depth, extinction coefficient, color ratio and depolarization ratio) were presented by statistical analysis over Eastern China (27°N~37°N and 113°E~123°E) during 2007~2016. The results showed that the aerosol optical depth (AOD) in Eastern China decreased from the north to south, and was higher in plain than in mountain. The seasonal AODs showed higher values in spring and summer, while lower in autumn and winter. The maximum AOD was in summer and the minimum in winter. The AOD in the north part (>31°N) showed more fluctuations than the south. The aerosol extinction coefficient (σ) had an exponential decay with the height. It showed large (small) σ in low layer but rapid (slow) decreasing with the height in autumn and winter (spring and summer). It showed higher σ in the north part than the south below 2km. The color ratios (CRs), with the annual mean values of 0.6~0.7, showed an increasing trend with the height and a decreasing trend with the time. The seasonal CRs below 4km had the maximum in spring and the minimum in summer which showed uniform vertical mixing. However, the CRs above 4km showed the maximum in winter while the minimum in summer. The annual mean depolarization ratios (PDRs) ranging from 0.1~0.25 increased with the height and presented higher values in the northern part. For seasonal PDR, it had the maximum in spring and the minimum in summer below 5km, while the highest in winter and the lowest in summer above 5km. For the aerosol compositions in Eastern China, the main pollutant below 2km was dust. For 2~5 km, it dominated by dust in spring and smoke in other seasons. Above 5km, the main pollutant was dust in winter and spring, while smoke in summer and autumn.