Large Eddy Simulation on Dust Suspension in a Convective Mixed Layer
Large Eddy Simulation on Dust Suspension in a Convective Mixed Layer
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DOI：
10.2151/sola.2010-034
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发表时间：
2010
期刊：
影响因子：
1.9
通讯作者：
J. Ito;H. Niino;M. Nakanishi
中科院分区：
文献类型：
--
作者：
J. Ito;H. Niino;M. Nakanishi
观测表明，在微风条件下，当对流混合层发展时，沙漠上空的光学厚度在白天增加。这意味着，即使在没有一般风的情况下，与对流运动相关的水平风也会产生尘埃悬浮。本文采用大涡模拟的方法，研究了在无一般风的情况下，对流混合层中悬浮粉尘的数量。结果表明，对流混合层中的沙尘颗粒浓度可达10μg m-3量级，与观测结果基本一致。末端速度较小的微小尘埃粒子很容易在白天被对流风吹起，整夜留在大气层中。如果类似的天气持续几天，第二天晚上的沙尘颗粒浓度可以达到第一天晚上的1.8倍。
Observations show that optical depth over desert increase during daytime when a convective mixed layer develops under a light general wind condition. This implies that dust suspension by horizontal winds associated with convective motions occur even in the absence of general winds. In the present paper, a large eddy simulation is performed to study how much dust is suspended in a convective mixed layer without a general wind. The results show that dust particle concentration in the convective mixed layer can reach on the order of 10 μg m-3, which is in reasonable agreement with observations. Tiny dust particles that have small terminal velocities are easily brought up by convective winds during daytime and remain in the atmosphere throughout night. If a similar weather continues for several days, dust particles concentration on the evening of the second day can reach 1.8 times as large as that on the evening of the first day, accordingly.