10–25-Day Intraseasonal Variability of Convection over the Sahel: A Role of the Saharan Heat Low and Midlatitudes
10–25-Day Intraseasonal Variability of Convection over the Sahel: A Role of the Saharan Heat Low and Midlatitudes
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萨赫勒地区对流 10-25 天季节内变化：撒哈拉低纬度和中纬度地区高温的作用
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
J. Lafore
中科院分区：
文献类型：
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作者：
R. Roehrig;F. Chauvin;J. Lafore
摘要：了解和预测西非季风（WAM）的持续干旱或湿润时期，特别是在季节内时间尺度上发生的时期，对于改善萨赫勒地区的粮食管理和减灾至关重要。在本研究中，作者评估了萨赫勒地区对流 10-25 天的季节内变化与最近记录的撒哈拉低热 (SHL) 和相关温带环流的季节内变化之间的关系。当 SHL 季节内波动领先于萨赫勒地区的对流波动且滞后 5 天时，就会发生最强和最频繁的相互作用。使用基于非线性事件的方法，这种组合被证明与萨赫勒地区三分之一的干旱和潮湿期有关，并且在干旱期的情况下，会产生更强的对流异常，持续时间至少延长 2 天，并达到更大的空间尺度。然后有人认为萨赫勒地区上空对流的 10-25 天季节内变化...
AbstractThe understanding and forecasting of persistent dry or wet periods of the West African monsoon (WAM), especially those that occur at the intraseasonal time scale, are crucial to improve food management and disaster mitigation in the Sahel region. In the present study, the authors assess how the 10–25-day intraseasonal variability of convection over the Sahel is related to the recently documented intraseasonal variability of the Saharan heat low (SHL) and the associated extratropical circulation. Strongest and most frequent interactions occur when the SHL intraseasonal fluctuations lead those of convection over the Sahel with a 5-day lag. Using a nonlinear event-based approach, such a combination is shown to concern about one-third of Sahelian dry and wet spells and, in the case of dry spells, to yield convective anomalies that are stronger, last longer by at least 2 days, and reach a larger spatial scale. It is then argued that the 10–25-day intraseasonal variability of convection over the Sahel c...