High‐resolution simulation of a major West African dust‐storm: comparison with observations and investigation of dust impact
High‐resolution simulation of a major West African dust‐storm: comparison with observations and investigation of dust impact
复制标题
西非重大沙尘暴的高分辨率模拟：与沙尘影响观测和调查的比较
DOI：
10.1002/qj.927
复制
发表时间：
2012
影响因子：
8.9
通讯作者：
Y. Seity
中科院分区：
文献类型：
--
作者：
C. Kocha;J. Lafore;P. Tulet;Y. Seity
本研究的重点是沙尘对2006年3月7日至15日期间发生的撒哈拉大沙尘暴的热力学和动力学的辐射影响。由于在对流尺度业务模式Arome内安装了尘埃模块，因此可以在大范围(6.5-30°N；3°W-33°E)范围内以高分辨率(5公里)进行为期10天的模拟。该模型能够反映这次沙尘暴的大部分生命周期和主要尘源的生命周期。根据与2006年AMMA野外活动框架内获得的一套完整和全面的测量结果的比较，该模拟成功地定性和定量地反映了风暴的主要热力学和辐射特征。与没有沙尘的模拟相比，与沙尘模块的耦合提供了与辐射和温度观测更一致的风暴特征。沙尘暴中心(2℃以上)的强烈加热导致了一个大的垂直位涡异常，低空位涡异常较大，中层位涡异常较弱，其下部和上部都有较大的位涡异常。这表明，与沙尘的耦合加强了冷温带爆发的强度，冷锋上升较多，近地面气旋辐合较多，高空反气旋辐散较多。此外，随着更多的北风，疫情爆发后部的下沉加剧。一个主要结果是沿锋面东风气流(∼3m S−1)在低层和非洲东风急流中加速，增加了沙尘的排放及其向西的远距离输送。版权所有(C)2011皇家气象学会
This study focuses on the radiative impacts of dust on the thermodynamics and dynamics of a major Saharan dust‐storm that occurred between 7 and 15 March 2006. The implementation of a dust module within the convective‐scale operational model AROME permitted a 10‐day simulation at high resolution (5 km) over a large domain (6.5–30°N; 3°W–33°E). The model is able to represent most of the life cycle of this dust‐storm and of the principal dust sources. According to the comparison with a complete and comprehensive set of measurements obtained within the framework of the AMMA field campaign in 2006, the simulation succeeds in representing the main thermodynamic and radiative features of the storm both qualitatively and quantitatively. As compared with a simulation without the dust, the coupling with the dust module provides signatures of the storm that are in better agreement with radiation and temperature observations. The intense heating in the core of the dust plume (more than 2°C) resulted in a large vertical dipole of potential vorticity anomaly with higher values at low levels and weaker values at mid levels, either in the lower and the upper part of the dust plume respectively. This shows that the coupling with dust reinforces the intensity of the cold extratropical outbreak with more ascent at the cold front, more cyclonic convergence near the surface, and more anticyclonic divergence aloft. Also, the subsidence is increased at the rear of the outbreak with more northerly winds. A major result is the acceleration of the easterly along‐front flow (∼3 m s−1) at low levels and in the African Easterly Jet, increasing the emission of dust and its westward long‐range transport. Copyright © 2011 Royal Meteorological Society