敦煌地区春季大气气溶胶粒子数浓度的分析

Analysis on Aerosol Particle Number Concentration over Dunhuang Region in Spring

利用2002年春季在敦煌地区戈壁沙漠和绿洲农田观测的大气气溶胶粒子数浓度资料，分析了它与沙尘天气的关系、谱分布特征以及两种地表下粒子数浓度的差异。结果表明，不同天气条件下的大气气溶胶粒子数浓度有着不同的特征。在背景天气下，敦煌地区的大气气溶胶粒子数浓度通常在10^4L^-1以下，其中以直径在0．5～1．0μm之间的极细颗粒为主，绿洲农田细粒子（直径〈3．0μm）的数浓度高于戈壁沙漠，而较粗粒子（直径〉3．0pm）则相反。当沙尘天气发生时，该地区的大气气溶胶粒子数浓度增大到10^5L^-1以上，直径在1．0～3．0μm之间的细粒子变为其主要成分，戈壁沙漠4档的粒子数浓度均高于绿洲农田，3．0μm以上的较粗粒子两地的差异更大。

Using the data of aerosol particle number concentration （APNC） observed over Gobi desert and oasis crop land in Dunhuang in spring of 2002, the relationship of APNC with dusty weather, spectrum distribution characteristics and differences of APNC over the two surfaces are analyzed in this paper. The results indicate that the characteristics of APNC will vary with different weather conditions. In background weather, the total APNC is usually under 10^4L^-1 and the main particles are very thin ones with diameter of 0.5-1.0μm. The APNC of thin particles （diameter〈3.0 μm） over oasis crop land are higher than those over Gobi desert, while it is opposite for coarse particles （diameter〉3.0 μm）. In dusty weath- er, the APNC in Dunhuang increases to be up to 10^5L^-1 and thin particles with diameter of 1.0-3.0 μm turn to be the main composition. All of the 4 classified APNC over Gobi desert are higher than that over oasis cropland, and this difference is much larger when the diameter is above 3.0μm.