DOI: 10.1002/2013JD019681
论文题名: Quasi-decadal signals of Sahel rainfall and West African monsoon since the mid-twentieth century
作者: Dieppois B. ; Diedhiou A. ; Durand A. ; Fournier M. ; Massei N. ; Sebag D. ; Xue Y. ; Fontaine B.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 22 起始页码: 12587
结束页码: 12599
语种: 英语
英文关键词: Quasi-decadal scale
; Sahel rainfall
; Sea-Surface Temperature
; West African Monsoon
; zonal contrast
Scopus关键词: Drought
; Oceanography
; Atmospheric anomaly
; Continuous Wavelet Transform
; Intertropical convergence zone
; Moisture convergence
; Quasi-decadal scale
; Sea surface temperatures
; West African Monsoon
; zonal contrast
; Rain
; decadal variation
; intertropical convergence zone
; monsoon
; pressure gradient
; rainfall
; reconstruction
; sea surface temperature
; troposphere
; twentieth century
; wetting-drying cycle
; Atlantic Ocean
; Sahel [Sub-Saharan Africa]
; West Africa
英文摘要: Sahel rainfall shows pronounced decadal variability and a negative trend between wet conditions in the 1950s-1960s and dry ones in the 1970s-1980s. Using continuous wavelet transform, the quasi-decadal variability (QDV) of rainfall reveals zonal contrasts. The highest QDV is identified in the 1950s-1960s over western Sahel and in the 1970s-1980s over eastern Sahel. The quasi-decadal atmospheric anomalies have been reconstructed using Fourier transform for the 1950s-1960s and the 1970s-1980s, respectively, and assessed by the composite analysis of the QDV phases for the periods before and after 1968. Over western Sahel, the rainfall QDV in the 1950s-1960s is related to the North Atlantic sea surface temperature (SST) variability, as highlighted by the wavelet coherence. A southward shift trend of the Intertropical Convergence Zone (ITCZ) is identified through an enhancement of northeasterly fluxes and moisture convergence over the western part of West Africa. A decrease (increase) of southern (northern) subtropical sinking motions seems to be involved. In the 1970s-1980s, a strengthening of cross-equatorial Atlantic SST and pressure gradients is related to an increase of monsoon flow from lower troposphere up to the midtroposphere and to the northward shift of the ITCZ, mainly over eastern Sahel. The Pacific SST influence is also identified, which involves changes in the global zonal circulation. Key Points Zonal contrasts are detected in Sahel rainfall at quasi-decadal scale Quasi-decadal signals of the WAM are identified in both wet and dry periods Modifications of SST forcing are observed between wet and dry periods ©2013. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63149
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Laboratoire Morphodynamique Continentale et Côtière, UMR 6143, FED 4116 SCALE, Place Emile Blondel, FR-76821 Mont-Saint Agnan, France; Laboratoire d'Étude des Transferts en Hydrologie et Environnement, Université de Grenoble, IRD, Grenoble, France; Laboratoire HydroSciences Montpellier, Université de Montpellier 2, IRD, Montpellier, France; Department of Geography, University of California, Los Angeles, CA, United States; Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, United States; Centre de Recherches en Climatologie, Université de Bourgogne, CNRS, Dijon, France
Recommended Citation:
Dieppois B.,Diedhiou A.,Durand A.,et al. Quasi-decadal signals of Sahel rainfall and West African monsoon since the mid-twentieth century[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(22)