DOI: 10.1175/JCLI-D-12-00598.1
Scopus记录号: 2-s2.0-84880301193
论文题名: Understanding hadley cell expansion versus contraction: Insights from simplified models and implications for recent observations
作者: Tandon N.F. ; Gerber E.P. ; Sobel A.H. ; Polvani L.M.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2013
卷: 26, 期: 12 起始页码: 4304
结束页码: 4321
语种: 英语
Scopus关键词: EL Nino
; General circulation model
; Hadley circulation
; Thermal forcing
; Transformed Eulerian means
; Upper troposphere
; Vertical structures
; Vertical velocity
; Climate change
; Clouds
; Dynamics
; Expansion
; Global warming
; Thermal expansion
; climate change
; climate forcing
; diabatic process
; El Nino
; Eulerian analysis
; general circulation model
; global warming
; Hadley cell
; troposphere
英文摘要: This study seeks a deeper understanding of the causes of Hadley Cell (HC) expansion, as projected under global warming, and HC contraction, as observed under El Niño. Using an idealized general circulation model, the authors show that a thermal forcing applied to a narrow region around the equator produces "El Niño-like" HC contraction, while a forcing with wider meridional extent produces "global warming-like" HC expansion. These circulation responses are sensitive primarily to the thermal forcing's meridional structure and are less sensitive to its vertical structure. If the thermal forcing is confined to the midlatitudes, the amount of HC expansion is more than three times that of a forcing of comparable amplitude that is spread over the tropics. This finding may be relevant to recently observed trends of rapid tropical widening. The shift of the HC edge is explained using a very simple model in which the transformed Eulerian mean (TEM) circulation acts to diffuse heat meridionally. In this context, the HC edge is defined as the downward maximum of residual vertical velocity in the upper troposphere ω̄max* ; this corresponds well with the conventional Eulerian definition of the HC edge. In response to a positive thermal forcing, there is anomalous diabatic cooling, and henceanomalous TEM descent, on the poleward flank of the thermal forcing. This causes the HC edge (ω̄max* ) to shift toward the descending anomaly, so that a narrow forcing causes HC contraction and a wide forcing causes HC expansion. © 2013 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/51820
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, United States; Center for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, New York, NY, United States; Department of Earth and Environmental Sciences, Columbia University, New York, NY, United States
Recommended Citation:
Tandon N.F.,Gerber E.P.,Sobel A.H.,et al. Understanding hadley cell expansion versus contraction: Insights from simplified models and implications for recent observations[J]. Journal of Climate,2013-01-01,26(12)