近10年东亚沙尘气溶胶时空分布与起尘通量的数值研究

利用一个耦合了沙尘模型的区域气候模式RegCM3和NCEP再分析资料,对近10年(2000-2009年)东亚地区沙尘气溶胶(直径≤20μm)时空分布特征和起尘通量进行了数值模拟。结果表明,(1)耦合模式能较好地模拟东亚地区沙尘气溶胶的时空分布特点。东亚地区沙尘气溶胶光学厚度、柱含量高值区主要位于塔克拉玛干沙漠和巴丹吉林沙漠。沙尘气溶胶柱含量的季节变化特征明显,春季最大,冬季次之,秋季最小。东亚地区110°E以东,沙尘主要以700hPa高度为中心向东传输。(2)东亚地区起沙源区主要位于塔克拉玛干沙漠、巴丹吉林沙漠、藏北沙漠化地区及蒙古国西南部,起沙强度存在明显的季节变化。2000-2009年东亚地区年平均起沙通量为1015.34mg.m-2.d-1,其中62.4%和2.3%分别通过干、湿过程重新沉降在东亚地区,其余35.3%被净释放进入大气或进行远距离传输。

Simulation Study on the Spatial and Temporal Distributions and Emission Flux of Dust Aerosol over East Asia in the Latest Decade

A regional climate model RegCM3 coupled with an on-line sandy dust module is used to simulate the dust aerosol(smaller than 20 μm in diameter) over East Asia in the latest decade from 2000 to 2009.The model is driven by NCEP re-analysis data.Based on the simulation results,the spatial and temporal distributions of sandy dust aerosol over East Asia are discussed,and the dust emission flux is also calculated.The model capability to simulate sandy dust aerosol is firstly validated.The simulation results show that the model can capture the characteristicsof spatial and temporal distributions of dust aerosol very well over East Asia.There always exist two extremes of dust aerosol optical depth and column burden,one is in the Taklimakan Desert of Xinjiang UygurAutonomous Region,China,and the other is in the Badain Juran Desert of Inner Mongolian Autonomous Region,China.The seasonal variation characteristic is evident,with the maximum value appears in spring,the secondary maximum in winterand the minimum in autumn.To the east of 110°E,the dust is transported eastward from a maximum center at a height of 700 hPa over East Asia.The dust emission sources are mainly located in the Taklimakan Desert,Badain Juran Desert,North Qinghai-Xizang Plateau and Southwest Mongolia.There is also an evident seasonal variation of dust emission flux.The annual mean dust emission flux is 1015.34 mg·m~-2·d~-1,of which 62.4% and 2.3% are re-deposited onto continentof East Asia through dry and wet deposition process,respectively,and the remaining 35.3% is injected into the atmosphere or subject to long-range transport.