DOI: 10.1007/s00382-014-2094-8
Scopus记录号: 2-s2.0-84894543687
论文题名: Atmospheric teleconnection mechanisms of extratropical North Atlantic SST influence on Sahel rainfall
作者: Liu Y. ; Chiang J.C.H. ; Chou C. ; Patricola C.M.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2014
卷: 43, 期: 2017-09-10 起始页码: 2797
结束页码: 2811
语种: 英语
英文关键词: Atmospheric teleconnection
; Monsoon
; North Atlantic cooling
; Sahel rainfall
英文摘要: Extratropical North Atlantic cooling has been tied to droughts over the Sahel in both paleoclimate observations and modeling studies. This study, which uses an atmospheric general circulation model (GCM) coupled to a slab ocean model that simulates this connection, explores the hypothesis that the extratropical North Atlantic cooling causes the Sahel droughts via an atmospheric teleconnection mediated by tropospheric cooling. The drying is also produced in a regional climate model simulation of the Sahel when reductions in air temperature (and associated geopotential height and humidity changes) from the GCM simulation are imposed as the lateral boundary conditions. This latter simulation explicitly demonstrates the central role of tropospheric cooling in mediating the atmospheric teleconnection from extratropical North Atlantic cooling. Diagnostic analyses are applied to the GCM simulation to infer teleconnection mechanisms. An analysis of top of atmosphere radiative flux changes diagnosed with a radiative kernel technique shows that extratropical North Atlantic cooling is augmented by a positive low cloud feedback and advected downstream, cooling Europe and North Africa. The cooling over North Africa is further amplified by a reduced greenhouse effect from decreased atmospheric specific humidity. A moisture budget analysis shows that the direct moisture effect and monsoon weakening, both tied to the ambient cooling and resulting circulation changes, and feedbacks by vertical circulation and evaporation augment the rainfall reduction. Cooling over the Tropical North Atlantic in response to the prescribed extratropical cooling also augments the Sahel drying. Taken together, they suggest a thermodynamic pathway for the teleconnection. The teleconnection may also be applicable to understanding the North Atlantic influence on Sahel rainfall over the twentieth century. © 2014, Springer-Verlag Berlin Heidelberg. 资助项目: NSF, National Science Foundation
; NSF, National Science Foundation
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54567
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Geography, University of California, 531 McCone Hall, Berkeley, CA, United States; Berkeley Center for Atmospheric Sciences, University of California, Berkeley, CA, United States; Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan; Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan; Department of Atmospheric Sciences, Texas A&M University, College Station, TX, United States
Recommended Citation:
Liu Y.,Chiang J.C.H.,Chou C.,et al. Atmospheric teleconnection mechanisms of extratropical North Atlantic SST influence on Sahel rainfall[J]. Climate Dynamics,2014-01-01,43(2017-09-10)