DOI: 10.1175/JCLI-D-11-00394.1
Scopus记录号: 2-s2.0-84859961201
论文题名: Role of the west African westerly jet in sahel rainfall variations
作者: Pu B. ; Cook K.H.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2012
卷: 25, 期: 8 起始页码: 2880
结束页码: 2896
语种: 英语
Scopus关键词: Africa
; Climate variability
; Decadal timescale
; Decadal variability
; Interannual
; Low-level features
; Moisture fluxes
; Moisture transport
; Precipitation anomalies
; Precipitation variability
; Precipitation variation
; Rainfall variation
; Relative vorticity
; Vorticity balance
; West African Monsoon
; Climatology
; Jets
; Moisture
; Precipitation (chemical)
; Vorticity
; Rain
; climate variation
; jet
; moisture flux
; moisture transfer
; precipitation (climatology)
; rainfall
; regional climate
; vorticity
; westerly
; West Africa
英文摘要: The West African westerly jet is a low-level feature of the summer climatology that transports moisture from the eastern Atlantic onto the African continent at 8°-11°N. This study examines the relationship between the jet and Sahel precipitation variability in August, when both the jet and rainfall reach their seasonal maxima. Variations of the West African westerly jet are significantly positively correlated with precipitation variations over the Sahel on both interannual and decadal time scales. Three periods are identified (1958-71, 1972-87, and 1988-2009), corresponding to timeswith a wet Sahel-strong jet, dry Sahel-weak jet, and relatively wet Sahel-strong jet. In wet (dry) periods, enhanced (decreased) westerlymoisture fluxes associated with a strong (weak) jet increase (decrease) the low-level moisture content over the Sahel, decreasing (enhancing) the stability of the atmosphere. This association between the jet and Sahel rainfall is also found in case studies of 1964, 1984, 1999, and 2007. The southerly moisture flux associated with the West African monsoon has less pronounced decadal variability than the westerly moisture flux of the West African westerly jet and weaker correlations with Sahel rainfall. When the monsoon flow is weak, for example, 1999 and 2007, the Sahel may still experience positive precipitation anomalies in association with strong westerly moisture transport by the jet. The West African westerly jet is also important for stabilizing the regional vorticity balance by introducing strong relative vorticity gradients. Northward flow advects low relative vorticity south of the jet to balance positive vorticity tendencies generated by midtropospheric condensation. © 2012 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/52485
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, United States; Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, United States; Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, United States
Recommended Citation:
Pu B.,Cook K.H.. Role of the west African westerly jet in sahel rainfall variations[J]. Journal of Climate,2012-01-01,25(8)