DOI: 10.1007/s00382-016-3106-7
Scopus记录号: 2-s2.0-84963754530
论文题名: An abrupt weakening of the subpolar gyre as trigger of Little Ice Age-type episodes
作者: Moreno-Chamarro E. ; Zanchettin D. ; Lohmann K. ; Jungclaus J.H.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2017
卷: 48, 期: 2017-03-04 起始页码: 727
结束页码: 744
语种: 英语
英文关键词: Abrupt shift
; Arctic freshwater export
; Last millennium
; Little Ice Age
; North Atlantic
; Subpolar gyre
英文摘要: We investigate the mechanism of a decadal-scale weakening shift in the strength of the subpolar gyre (SPG) that is found in one among three last millennium simulations with a state-of-the-art Earth system model. The SPG shift triggers multicentennial anomalies in the North Atlantic climate driven by long-lasting internal feedbacks relating anomalous oceanic and atmospheric circulation, sea ice extent, and upper-ocean salinity in the Labrador Sea. Yet changes throughout or after the shift are not associated with a persistent weakening of the Atlantic Meridional Overturning Circulation or shifts in the North Atlantic Oscillation. The anomalous climate state of the North Atlantic simulated after the shift agrees well with climate reconstructions from within the area, which describe a transition between a stronger and weaker SPG during the relatively warm medieval climate and the cold Little Ice Age respectively. However, model and data differ in the timing of the onset. The simulated SPG shift is caused by a rapid increase in the freshwater export from the Arctic and associated freshening in the upper Labrador Sea. Such freshwater anomaly relates to prominent thickening of the Arctic sea ice, following the cluster of relatively small-magnitude volcanic eruptions by 1600 CE. Sensitivity experiments without volcanic forcing can nonetheless produce similar abrupt events; a necessary causal link between the volcanic cluster and the SPG shift can therefore be excluded. Instead, preconditioning by internal variability explains discrepancies in the timing between the simulated SPG shift and the reconstructed estimates for the Little Ice Age onset. © 2016, The Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/53349
Appears in Collections: 过去全球变化的重建
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作者单位: Max Planck Institute for Meteorology, Hamburg, Germany; International Max Planck Research School on Earth System Modeling, Hamburg, Germany; University of Venice, Venice, Italy
Recommended Citation:
Moreno-Chamarro E.,Zanchettin D.,Lohmann K.,et al. An abrupt weakening of the subpolar gyre as trigger of Little Ice Age-type episodes[J]. Climate Dynamics,2017-01-01,48(2017-03-04)