气候变化领域集成服务门户(CCPortal): Role of the West African westerly jet in the seasonal and diurnal cycles of precipitation over West Africa

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DOI	10.1007/s00382-019-05035-1
	Role of the West African westerly jet in the seasonal and diurnal cycles of precipitation over West Africa
	Liu W.; Cook K.H.; Vizy E.K.
发表日期	2020
ISSN	0930-7575
起始页码	843
结束页码	861
卷号	54 期号:2020-01-02
英文摘要	The West African westerly jet (WAWJ) is a low-level jet centered near 10° N over the West African coast from June to September. This study quantifies the low-level moisture transport associated with the WAWJ on seasonal timescales, examines the relationship between the jet and West African precipitation using a moisture budget analysis, and further distinguishes the WAWJ from the West African monsoon (WAM) flow. Three reanalyses and five observational rainfall datasets are examined to build confidence. The WAWJ has a diurnal cycle with a minimum at 12 UTC and a maximum at 18 UTC, dominated by the ageostrophic wind component. According to the momentum budget analysis, the diurnal acceleration/deceleration of the WAWJ is controlled by variations in geopotential height gradient forces associated with the continental thermal low and its westward, offshore extension over the eastern Atlantic. The WAWJ wind speed and rainfall across a large region of the western Sahel (0°–10°W, 8°–18° N) are significantly and positively correlated. In this region, the moisture flux associated with the WAWJ is stronger than that associated with the southerly WAM flow from July 5 to August 20 (45 days). The moisture budget analysis reveals that the seasonal evolution of the rainfall in this analysis region is associated with zonal moisture convergence related to changes of the WAWJ. Enhanced (reduced) rainfall occurs in months with a strong (weak) WAWJ, accompanied by low-level moisture flux anomalies associated with the WAWJ instead of the southerly WAM. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
英文关键词	Diurnal cycle; Low-level jet; Saharan thermal low; Sahel rainfall; Seasonality of precipitation; West African monsoon; West African westerly jet
语种	英语
scopus关键词	diurnal variation; jet; monsoon; precipitation assessment; precipitation intensity; seasonal variation; temperature effect; westerly; Sahel [Sub-Saharan Africa]
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/145787
作者单位	Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, 1 University Station C1100, Austin, TX, United States
推荐引用方式 GB/T 7714	Liu W.,Cook K.H.,Vizy E.K.. Role of the West African westerly jet in the seasonal and diurnal cycles of precipitation over West Africa[J],2020,54(2020-01-02).
APA	Liu W.,Cook K.H.,&Vizy E.K..(2020).Role of the West African westerly jet in the seasonal and diurnal cycles of precipitation over West Africa.Climate Dynamics,54(2020-01-02).
MLA	Liu W.,et al."Role of the West African westerly jet in the seasonal and diurnal cycles of precipitation over West Africa".Climate Dynamics 54.2020-01-02(2020).