Model study on particle size segregation and deposition during Asian dust events in March 2002
Model study on particle size segregation and deposition during Asian dust events in March 2002
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DOI：
10.1029/2004jd004920
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发表时间：
2004-10-12
影响因子：
4.4
通讯作者：
Hasome, H
中科院分区：
文献类型：
--
作者：
Han, ZW;Ueda, H;Hasome, H
[1]建立了一个包括大多数主要物理过程(生成、输送、干湿沉积)的尺寸分离气溶胶模式。该模式与区域空气质量模式(RAQM)相结合，用于模拟2002年3月15日至24日这10天期间的亚洲沙尘暴。非静力中尺度模式(MM5)用于提供气象场。模型结果得到了可用观测数据的验证，包括地面天气观测和尺寸分离的颗粒浓度。验证结果表明，该模型系统能够很好地捕捉沙尘演化的大部分关键特征，并能再现土壤沙尘沿输送路径的颗粒质量分布。模式观测到并再现了一个明显的特征，即在从源区到遥远的下风区的路径上，随着峰值质量浓度从粗模向细模的转移，尺度范围发生了移动。模拟的10天平均最大沙尘浓度为3000mug m(-3)，位于中国-蒙古国南部边界。中国-蒙古国南部戈壁沙漠10天的土壤沙尘干沉降量高达30gm(-2)。颗粒沉积的分布和大小强烈依赖于浓度和粒度分离的干沉积速度和清扫率。干沉降对源区内或附近沙尘颗粒的去除起主导作用，湿沉降的影响沿土壤沙尘的运移路径增加，对粗颗粒(>；2 um)的去除效率较高，而对堆积模式下的颗粒去除效率很低。在总扬尘排放量(4320万吨)中，约71%通过干沉积过程重新沉积到下垫面，6%通过湿沉积过程去除，其余23%悬浮在大气中或进行远程输送。
[1] A size-segregated aerosol model that includes most of the major physical processes ( generation, transport, and dry and wet deposition) is developed. This model is coupled with a Regional Air Quality Model (RAQM) and is applied to simulate Asian dust storms during the 10-day period of 15 - 24 March 2002. A nonhydrostatic mesoscale model (MM5) is used to provide meteorological fields. Model results are verified by available observational data including surface weather observations and size-segregated particle concentrations. The validation demonstrates a good capability of this model system in capturing most of the key features of dust evolution and reproducing the particle mass size distribution along the transport pathway of soil dust. An apparent feature has been both observed and reproduced by the model, showing a shift of size range with peak mass concentration from coarse mode to finer mode on the pathway from source regions to distant downwind areas. The maximum dust concentration averaged over 10 days is simulated to be 3000 mug m(-3) over the southern China-Mongolia border. Total dry deposition of soil dust for 10 days is up to 30 g m(-2) in the Gobi desert along the southern China-Mongolia border. Distribution and magnitude of particle deposition are strongly dependent on both concentration and size-segregated dry deposition velocity and scavenging rate. While dry deposition dominates the removal of dust particles in or in the vicinity of source regions, the influence of wet deposition increases along the transport pathway of soil dust, with high removal efficiency for coarser particles (> 2 mum) and very low efficiency for particles in the accumulation mode. Of the total dust emission (43.2 megatons), about 71% is redeposited onto the underlying surface by the dry deposition process, 6% is removed by the wet deposition process, and the remaining 23% is suspended in the atmosphere or subject to long-range transport.