DOI: 10.1175/JCLI-D-12-00495.1
Scopus记录号: 2-s2.0-84878974777
论文题名: Southern annular mode dynamics in observations and models. part ii: Eddy Feedbacks
作者: Simpson I.R. ; Shepherd T.G. ; Hitchcock P. ; Scinocca J.F.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2013
卷: 26, 期: 14 起始页码: 5220
结束页码: 5241
语种: 英语
Scopus关键词: Climatological circulation
; Coupled Model Intercomparison Project
; Feedback strength
; Global climate model
; Middle atmosphere model
; Southern Annular Mode
; Southern Hemisphere
; Zonal wavenumber
; Climate models
; Computer simulation
; Feedback
; atmospheric forcing
; atmospheric modeling
; climate feedback
; climate modeling
; climatology
; computer simulation
; eddy
; planetary wave
; Southern Hemisphere
; Canada
英文摘要: Many global climate models (GCMs) have trouble simulating southern annular mode (SAM) variability correctly, particularly in the Southern Hemisphere summer season where it tends to be too persistent. In this two-part study, a suite of experiments with the Canadian Middle Atmosphere Model (CMAM) is analyzed to improve the understanding of the dynamics of SAM variability and its deficiencies in GCMs. Here, an examination of the eddy-mean flow feedbacks is presented by quantification of the feedback strength as a function of zonal scale and season using a new methodology that accounts for intraseasonal forcing of the SAM. In the observed atmosphere, in the summer season, a strong negative feedback by planetary-scale waves, in particular zonal wavenumber 3, is found in a localized region in the southwest Pacific. It cancels a large proportion of the positive feedback by synoptic- and smaller-scale eddies in the zonal mean, resulting in a very weak overall eddy feedback on the SAM. CMAM is deficient in this negative feedback by planetary-scale waves, making a substantial contribution to its bias in summertime SAMpersistence. Furthermore, this bias is not alleviated by artificially improving the climatological circulation, suggesting that climatological circulation biases are not the cause of the planetary wave feedback deficiency in the model. Analysis of the summertime eddy feedbacks in the models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) confirms that this is indeed a common problem among GCMs, suggesting that understanding this planetary wave feedback and the reason for its deficiency in GCMs is key to improving the fidelity of simulated SAM variability in the summer season. ©2013 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/51793
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Physics, University of Toronto, Toronto, ON, Canada; Division of Ocean and Climate Physics, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, United States; Department of Meteorology, University of Reading, Reading, United Kingdom; Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria, BC, Canada; Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
Recommended Citation:
Simpson I.R.,Shepherd T.G.,Hitchcock P.,et al. Southern annular mode dynamics in observations and models. part ii: Eddy Feedbacks[J]. Journal of Climate,2013-01-01,26(14)