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首页> 外文期刊>Pure and Applied Geophysics >The Influence of the Regional Hadley and Walker Circulations on Precipitation Patterns over Africa in El Nio, La Nia, and Neutral Years
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The Influence of the Regional Hadley and Walker Circulations on Precipitation Patterns over Africa in El Nio, La Nia, and Neutral Years

机译：哈德利地区哈德利和步行者循环对El Nio，La Nia和中立年降水模式的影响

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摘要

This study focuses on the differential impacts of the positive (El Nio), negative (La Nia), and neutral phases of the El Nio Southern Oscillation (ENSO) on precipitation over Africa during DJF and JJA, evaluated through changes in the regional Hadley and Walker Circulations. Identification of the Hadley and Walker Cells was done using stream function mass transport calculations of ERA-Interim reanalysis data from 1979 to 2014. Analysis of the spatial pattern of precipitation anomalies shows that during DJF, El Nio (La Nia) negatively (positively) impacts precipitation over the African continent. During JJA, El Nio (La Nia) influences precipitation variability over the Sahel region, producing positive (negative) anomalies. Negative precipitation anomalies associated with El Nio (DJF) over southern Africa are linked to a strengthening in subsidence of the descending branch of the regional Hadley Cell, and during JJA the negative precipitation anomalies over the Sahel are associated with a weakening of the ascending branch of the regional Hadley Cell. During La Nia events in DJF, there is a tendency toward increased convection in southern Africa, associated with a stronger ascending branch and weaker descending branch of the regional Hadley Cell. During La Nia events in JJA, positive precipitation anomalies over the Sahel are associated with an intensification of the ascending branch of the regional Hadley Cell north of the equator.
机译：本研究主要通过区域哈德利和沃克环流的变化，评估了在DJF和JJA期间，厄尔尼诺南方涛动（ENSO）的正（厄尔尼诺）、负（拉尼亚）和中性阶段对非洲降水的差异影响。利用1979年至2014年ERA中期再分析数据的流函数质量传输计算，对哈德利和沃克细胞进行了识别。降水异常的空间格局分析表明，在DJF期间，厄尔尼诺（La Nio）对非洲大陆的降水产生了负面（正面）影响。在JJA期间，厄尔尼诺影响萨赫勒地区的降水变化，产生正（负）异常。与南部非洲厄尔尼诺现象（DJF）相关的负降水异常与区域哈德利细胞下降分支的沉降增强有关，在JJA期间，萨赫勒地区的负降水异常与区域哈德利细胞上升分支的减弱有关。在DJF的La Nia事件期间，南部非洲的对流有增加的趋势，这与区域Hadley Cell较强的上升分支和较弱的下降分支有关。在JJA的拉尼亚事件期间，萨赫勒上空的正降水异常与赤道以北区域哈德利细胞上升分支的增强有关。

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