DOI: 10.1175/JCLI-D-11-00460.1
Scopus记录号: 2-s2.0-84865191283
论文题名: Exploring mechanisms of variability and predictability of Atlantic meridional overturning circulation in two coupled climate models
作者: Tulloch R. ; Marshall J.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2012
卷: 25, 期: 12 起始页码: 4067
结束页码: 4080
语种: 英语
Scopus关键词: Atlantic meridional overturning circulations
; Center frequency
; Community climate system model
; Coupled climate model
; Coupled models
; Density anomalies
; Diagnostic approach
; Driving mechanism
; Key variables
; Labrador Sea
; Mann eddies
; Multidecadal variability
; North Atlantic Currents
; Power-spectra
; Q-factors
; Quality factors
; Stochastic winds
; Subpolar gyres
; Thermal winds
; Toy models
; Eddy currents
; Oceanography
; Q factor measurement
; Climate models
; climate modeling
; climate prediction
; decadal variation
; eddy
; meridional circulation
; oceanic current
; upper ocean
; wind forcing
; Atlantic Ocean
; Atlantic Ocean (North)
; Labrador Sea
英文摘要: Multidecadal variability in the Atlantic meridional overturning circulation (AMOC) of the ocean is diagnosed in the NCAR Community Climate System Model, version 3 (CCSM3), and the GFDL Coupled Model (CM2.1). Common diagnostic approaches are applied to draw out similarities and differences between the two models. An index of AMOC variability is defined, and the manner in which key variables covary with it is determined. In both models the following is found. (i) AMOC variability is associated with upper-ocean (top 1 km) density anomalies (dominated by temperature) on the western margin of the basin in the region of the Mann eddy with a period of about 20 years. These anomalies modulate the trajectory and strength of the North Atlantic Current. The importance of the western margin is a direct consequence of the thermal wind relation and is independent of the mechanisms that create those density anomalies. (ii) Density anomalies in this key region are part of a larger-scale pattern that propagates around the subpolar gyre and acts as a "pacemaker" of AMOC variability. (iii) The observed variability is consistent with the primary driving mechanism being stochastic wind curl forcing, with Labrador Sea convection playing a secondary role. Also, "toy models" of delayed oscillator form are fitted to power spectra of key variables and are used to infer "quality factors" (Q-factors), which characterize the bandwidth relative to the center frequency and hence AMOC predictability horizons. The two models studied here have Q-factors of around 2, suggesting that prediction is possible out to about two cycles, which is likely larger than the real AMOC. © 2012 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/52387
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
Recommended Citation:
Tulloch R.,Marshall J.. Exploring mechanisms of variability and predictability of Atlantic meridional overturning circulation in two coupled climate models[J]. Journal of Climate,2012-01-01,25(12)