沙尘气溶胶光学厚度的全球分布及分析

The Optical Depth Global Distribution of Dust Aerosol and Its Possible Reason Analysis

利用全球气溶胶数据GADS（Global Aerosol Data Set）计算了冬夏两季4种类型（积聚型、核型、粗粒型和传输型）沙尘气溶胶0．55μm光学厚度的全球分布。通过分析得出，气溶胶的消光系数和垂直厚度对光学厚度的影响很大。全球沙尘气溶胶分布具有明显的季节和地理差异，4个沙尘暴多发区，分别位于北非、中亚地区、澳大利亚西部和北美西部。中亚地区冬季沙尘气溶胶强度和范围比夏季大，北美和澳大利亚地区则相反，冬季光学厚度最大值位于北非的中部地区，而夏季其最大值位于非洲北部靠近大西洋的地区。沙尘气溶胶对〈8μm的辐射吸收作用很弱，散射能力较强；对于〉8μm的辐射吸收能力很强，吸收带位主要于8～11μm范围内。

GADS （Global Aerosol Data Set） data and software is adopted to calculate AOD （Aerosol optical depth） （λ=0.55μm） of four types dust aerosol （accumulation, nucleus, coarse, transmission） for winter and summer. The result shows that the extinction coefficient and vertical geometric thickness of aerosol take a great effect on AOD. There is obvious seasonal and geographical difference for the distribution of global dust aerosols. There are four typical regions in the world for dust aerosol, located in North Africa, Central Asia, West Australia and North America respectively. The intensity and extension of central Asia dust aerosol in winter are larger than those in summer, while those of the North America and Australia is just in opposite. The maximum value of AOD of dust aerosol exists in North Africa no matter in winter or summer. Dust aerosols absorb shortwave less than 8μm weakly and its absorption band is in 8-11μm. The extinction effect is mainly caused by particle scattering less than 8 μm and absorbing larger than 8μm.