DOI: 10.1175/JCLI-D-11-00023.1
Scopus记录号: 2-s2.0-84876078271
论文题名: The leading, interdecadal eigenmode of the atlantic meridional overturning circulation in a realistic ocean model
作者: Sévellec F. ; Fedorov A.V.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2013
卷: 26, 期: 7 起始页码: 2160
结束页码: 2183
语种: 英语
Scopus关键词: Atlantic meridional overturning circulations
; Climate variability
; Continuous integrations
; Meridional temperature gradient
; North Atlantic Ocean
; Ocean general circulation models
; Tangent linear models
; Temperature anomaly
; Advection
; Climatology
; Ocean currents
; Thermal gradients
; advection
; air-sea interaction
; atmospheric structure
; baroclinic wave
; climate variation
; decadal variation
; eigenvalue
; meridional circulation
; oceanic general circulation model
; Rossby wave
; temperature anomaly
; temperature gradient
; Atlantic Ocean
; Atlantic Ocean (North)
英文摘要: Variations in the strength of the Atlantic meridional overturning circulation (AMOC) are a major potential source of decadal and longer climate variability in the Atlantic. This study analyzes continuous integrations of tangent linear and adjoint versions of an ocean general circulation model [Océan Paralleélisé (OPA)] and rigorously shows the existence of a weakly damped oscillatory eigenmode of the AMOCcentered in the North Atlantic Ocean and controlled solely by linearized ocean dynamics. In this particular GCM, the mode period is roughly 24 years, its e-folding decay time scale is 40 years, and it is the least-damped oscillatory mode in the system. Its mechanism is related to the westward propagation of large-scale temperature anomalies in the northern Atlantic in the latitudinal band between 30° and 60°N. The westward propagation results froma competition among mean eastward zonal advection, equivalent anomalous westward advection caused by the mean meridional temperature gradient, and westward propagation typical of long baroclinic Rossby waves. The zonal structure of temperature anomalies alternates between a dipole (corresponding to an anomalous AMOC) and anomalies of one sign (yielding no changes in the AMOC). Further, it is shown that the system is nonnormal, which implies that the structure of the least-damped eigenmode of the tangent linear model is different from that of the adjoint model. The "adjoint" mode describes the sensitivity of the system(i.e., it gives the most efficient patterns for exciting the leading eigenmode). An idealized model is formulated to highlight the role of the background meridional temperature gradient in the North Atlantic for the mode mechanism and the system nonnormality. © 2013 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/51968
Appears in Collections: 气候变化事实与影响
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作者单位: Ocean and Earth Science, National Oceanographic Centre Southampton, University of Southampton, Southampton, United Kingdom; Department of Geology and Geophysics, Yale University, New Haven, CT, United States
Recommended Citation:
Sévellec F.,Fedorov A.V.. The leading, interdecadal eigenmode of the atlantic meridional overturning circulation in a realistic ocean model[J]. Journal of Climate,2013-01-01,26(7)