气候变化领域集成服务门户(CCPortal): The Angola Low: relationship with southern African rainfall and ENSO

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DOI	10.1007/s00382-018-4222-3
	The Angola Low: relationship with southern African rainfall and ENSO
	Crétat J.; Pohl B.; Dieppois B.; Berthou S.; Pergaud J.
发表日期	2019
ISSN	0930-7575
起始页码	1783
结束页码	1803
卷号	52 期号:2020-03-04
英文摘要	The main states of the Angola Low (AL) are identified using clustering analysis applied to daily anomalous patterns of 700-hPa wind vorticity over Angola and adjacent countries from November to March for the 1980/81–2014/15 period. At the daily timescale, we examine the extent to which the main states of the AL modulate daily rainfall over southern Africa. At the interannual timescale, we assess both the relationship between the occurrence of these AL states and El Niño southern oscillation (ENSO) and the role of the AL in explaining ENSO’s failure in driving southern African rainfall at times. Three reanalyses are considered to account for uncertainties induced by the scarcity of data available for assimilation over southern Africa. Three preferential states of the Angola Low are identified: AL state close to its seasonal climatology with slight zonal displacements, anomalously weak AL state and anomalously strong AL state with meridional displacements. These different states all significantly modulate daily southern African rainfall. Near-climatological AL state promotes wet rainfall anomalies over eastern subtropical southern Africa and dry rainfall anomalies over its western part. A slight westward shift in the near-climatological position of the AL leads to reversed zonal gradient in rainfall. The remaining regimes significantly modulate the meridional gradient in southern African rainfall. Anomalously weak and anomalously northward AL states promote wet rainfall anomalies over tropical southern Africa and dry rainfall anomalies over subtropical southern Africa. The reverse prevails for anomalously southward AL. At the interannual timescale, ENSO significantly modulates the seasonal occurrence of most AL states in the three reanalyses. Anomalously weak and southward AL states are more strongly correlated with regional rainfall than ENSO in all reanalyses, suggesting that accounting for AL variability may improve seasonal forecasts. Case study analysis of the major 1982/83 and 1997/98 El Niño events suggests that the weak rainfall anomalies and strong seasonal AL in 1997/98 may result from counteracting effects between ENSO and Indian Ocean coupled modes of variability. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
英文关键词	Angola Low; Clustering analysis; Daily rainfall; ENSO; Interannual variability; Southern Africa
语种	英语
scopus关键词	annual variation; climatology; cluster analysis; El Nino-Southern Oscillation; rainfall; vorticity; Angola; Indian Ocean
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/146558
作者单位	LOCEAN Laboratory, IPSL, Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, Boîte 100-4, place Jussieu, Paris Cedex 05, 75252, France; Centre de Recherches de Climatologie, UMR 6282 Biogéosciences, CNRS/Université de Bourgogne Franche-Comté, Dijon, France; Centre for Agroecology, Water and Resilience (CAWR), Coventry University, Ryton-on-Dunsmore, Coventry, United Kingdom; Department of Oceanography, University of Cape Town, Rondebosh, Cape Town, South Africa; School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom; Met Office, Hadley Centre, Exeter, United Kingdom
推荐引用方式 GB/T 7714	Crétat J.,Pohl B.,Dieppois B.,et al. The Angola Low: relationship with southern African rainfall and ENSO[J],2019,52(2020-03-04).
APA	Crétat J.,Pohl B.,Dieppois B.,Berthou S.,&Pergaud J..(2019).The Angola Low: relationship with southern African rainfall and ENSO.Climate Dynamics,52(2020-03-04).
MLA	Crétat J.,et al."The Angola Low: relationship with southern African rainfall and ENSO".Climate Dynamics 52.2020-03-04(2019).