DOI: 10.1007/s00382-014-2270-x
Scopus记录号: 2-s2.0-84926352934
论文题名: On the reduced sensitivity of the Atlantic overturning to Greenland ice sheet melting in projections: a multi-model assessment
作者: Swingedouw D. ; Rodehacke C.B. ; Olsen S.M. ; Menary M. ; Gao Y. ; Mikolajewicz U. ; Mignot J.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2015
卷: 44, 期: 2017-11-12 起始页码: 3261
结束页码: 3279
语种: 英语
英文关键词: AMOC
; Greenland ice sheet melting
; North Atlantic
; Oceanic dynamics
; Oceanic gyre
; Ocean–atmosphere interactions
; Sea-level rise
; Thermohaline circulation
英文摘要: Large uncertainties exist concerning the impact of Greenland ice sheet melting on the Atlantic meridional overturning circulation (AMOC) in the future, partly due to different sensitivity of the AMOC to freshwater input in the North Atlantic among climate models. Here we analyse five projections from different coupled ocean–atmosphere models with an additional 0.1 Sv (1 Sv = 106 m3/s) of freshwater released around Greenland between 2050 and 2089. We find on average a further weakening of the AMOC at 26°N of 1.1 ± 0.6 Sv representing a 27 ± 14 % supplementary weakening in 2080–2089, as compared to the weakening relative to 2006–2015 due to the effect of the external forcing only. This weakening is lower than what has been found with the same ensemble of models in an identical experimental set-up but under recent historical climate conditions. This lower sensitivity in a warmer world is explained by two main factors. First, a tendency of decoupling is detected between the surface and the deep ocean caused by an increased thermal stratification in the North Atlantic under the effect of global warming. This induces a shoaling of ocean deep ventilation through convection hence ventilating only intermediate levels. The second important effect concerns the so-called Canary Current freshwater leakage; a process by which additionally released freshwater in the North Atlantic leaks along the Canary Current and escapes the convection zones towards the subtropical area. This leakage is increasing in a warming climate, which is a consequence of decreasing gyres asymmetry due to changes in Ekman pumping. We suggest that these modifications are related with the northward shift of the jet stream in a warmer world. For these two reasons the AMOC is less susceptible to freshwater perturbations (near the deep water formation sides) in the North Atlantic as compared to the recent historical climate conditions. Finally, we propose a bilinear model that accounts for the two former processes to give a conceptual explanation about the decreasing AMOC sensitivity due to freshwater input. Within the limit of this bilinear model, we find that 62 ± 8 % of the reduction in sensitivity is related with the changes in gyre asymmetry and freshwater leakage and 38 ± 8 % is due to the reduction in deep ocean ventilation associated with the increased stratification in the North Atlantic. © 2014, Springer-Verlag Berlin Heidelberg. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54115
Appears in Collections: 过去全球变化的重建
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作者单位: EPOC laboratory, CNRS / University of Bordeaux, Allée Geoffroy Saint Hilaire, Bordeaux, France; DMI, Copenhagen, Denmark; Max-Planck-Institut für Meteorologie, Hamburg, Germany; Hadley Centre, Exeter, United Kingdom; NERSC, Bergen, Norway; LOCEAN Laboratory, Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, 4 Place Jussieu, Paris, France; Climate and Environmental Physics, Physics Institute and Oeschger Centre of Climate Change Research, University of Bern, Bern, Switzerland
Recommended Citation:
Swingedouw D.,Rodehacke C.B.,Olsen S.M.,et al. On the reduced sensitivity of the Atlantic overturning to Greenland ice sheet melting in projections: a multi-model assessment[J]. Climate Dynamics,2015-01-01,44(2017-11-12)