| DOI: | 10.1007/s00382-015-2864-y
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| Scopus记录号: | 2-s2.0-84944600099
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| 论文题名: | The Congo Basin Walker circulation: dynamics and connections to precipitation |
| 作者: | Cook K.H.; Vizy E.K.
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| 刊名: | Climate Dynamics
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| ISSN: | 9307575
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| 出版年: | 2016
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| 卷: | 47, 期:2017-03-04 | | 起始页码: | 697
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| 结束页码: | 717
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| 语种: | 英语
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| 英文关键词: | African precipitation
; Atlantic cold tongue
; Congo Basin
; Equatorial Atlantic
; Sahel precipitation
; Walker circulation
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| 英文摘要: | The existence, seasonality, and variability of a Congo Basin Walker circulation are investigated in reanalyses, and connections with rainfall are explored. A zonal overturning circulation along the equator connects rising motion in the Congo Basin and sinking in the eastern Atlantic during June through October. This timing is out of phase with precipitation over equatorial Africa, which greatest during spring and fall, and does not correlate with the seasonality of land temperatures. Rather, the zonally-overturning circulation only occurs when the Atlantic cold tongue has formed. Although the cold tongue formation is essential for setting up the Congo Basin Walker circulation, variations in equatorial eastern Atlantic sea surface temperatures are not associated with interannual variability in the strength of the circulation. When cold tongue SSTs are anomalously cool (warm), evaporation from the ocean surface is reduced (enhanced) and the westerly flow advects less (more) moisture into the base of the Congo Basin Walker circulation. This reduces (increases) the release of latent heat in the upbranch and weakens (strengthens) the Walker circulation. This process dominates the pure dry dynamical response to enhanced land/sea temperature differences, which has an opposite sign. A positive correlation connects low-level vertical velocity in the Congo basin with low-level vertical velocity and precipitation over West Africa. A wave response to anomalous vertical velocity in the Congo Basin in several reanalyses suggests a teleconnection into West Africa such that an anomalously strong (weak) upbranch is associated with anomalously strong (weak) rainfall over the Guinean coast and southern Sahel. © 2015, Springer-Verlag Berlin Heidelberg. |
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| 资源类型: | 期刊论文
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/53601
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| Appears in Collections: | 过去全球变化的重建
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作者单位: | Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, United States
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| Recommended Citation: | |
Cook K.H.,Vizy E.K.. The Congo Basin Walker circulation: dynamics and connections to precipitation[J]. Climate Dynamics,2016-01-01,47(2017-03-04)
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