Convergence zones and their impact on the initiation of a mesoscale convective system in West Africa
Convergence zones and their impact on the initiation of a mesoscale convective system in West Africa
复制标题
辐合区及其对西非中尺度对流系统启动的影响
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
C. Taylor
中科院分区：
文献类型：
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作者：
V. Klüpfel;N. Kalthoff;L. Gantner;C. Taylor
在2006年非洲季风多学科分析（AMMA）活动期间，进行了扩展的地表和边界层测量，以研究土壤水分模式对热强迫环流的产生和深层对流的触发的影响。然而，在以往的研究中，并不是所有与中尺度对流系统（MCS）触发有关的过程都能被识别出来。因此，COSMO （Consortium for Small scale Modeling）进行了模拟，研究可能的触发机制。2006年7月31日，一个MCS启动，8月1日，土壤水分不均匀导致一个热强迫环流和一个辐合带，但没有引发深层对流。结果表明，7月31日的MCS受到一个气旋涡旋的影响，并受到两个不同起源辐合带叠加的有利影响。在模拟过程中，湿季风气流向北输送，与另一个MCS前方的冷池相关联，到达辐合带，形成MCS。8月1日，模拟重现了由MCS降水产生的土壤-湿度模式引起的热强迫环流。但由于边界层湿度低，对流有效势能低，辐合带抬升并未引发深部对流。版权所有©2011英国皇家气象学会
During the African Monsoon Multidisciplinary Analysis (AMMA) campaign in 2006, extended surface and boundary‐layer measurements were performed to study the influence of soil‐moisture patterns on the generation of thermally forced circulations and triggering of deep convection. However, not all processes involved in the triggering of a mesoscale convective system (MCS) could be identified in previous studies. Therefore, COSMO (Consortium for Small‐scale Modeling) simulations were carried out investigating possible trigger mechanisms. On 31 July 2006, an MCS was initiated and on 1 August, soil‐moisture inhomogeneities resulted in a thermally forced circulation with an associated convergence zone, but no deep convection was triggered. It was found that the MCS on 31 July was influenced by a cyclonic vortex and favoured by the superposition of two convergence zones of different origins. Initiation of the MCS occurred in the simulation when moist monsoon air was transported to the north, associated with a cold pool ahead of another MCS, and reached the convergence zone. On 1 August, the simulation reproduced the thermally forced circulation caused by the soil‐moisture pattern, which had been produced by the precipitation of the MCS. However, due to low humidity in the boundary layer and low convective available potential energy, the lifting along the convergence zone did not trigger deep convection. Copyright © 2011 Royal Meteorological Society