DOI: 10.5194/cp-12-1663-2016
Scopus记录号: 2-s2.0-85016142205
论文题名: Hosed vs. unhosed: Interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing
作者: Brown N. ; Galbraith E.D.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2016
卷: 12, 期: 8 起始页码: 1663
结束页码: 1679
语种: 英语
Scopus关键词: air temperature
; atmosphere-ocean coupling
; climate variation
; dissolved oxygen
; freshwater input
; halocline
; Heinrich event
; iceberg
; meridional circulation
; overturn
; precipitation (climatology)
; Atlantic Ocean
; Atlantic Ocean (North)
; Pacific Ocean
; Pacific Ocean (North)
; Southern Ocean
英文摘要: It is well known that glacial periods were punctuated by abrupt climate changes, with large impacts on air temperature, precipitation, and ocean circulation across the globe. However, the long-held idea that freshwater forcing, caused by massive iceberg discharges, was the driving force behind these changes has been questioned in recent years. This throws into doubt the abundant literature on modelling abrupt climate change through "hosing" experiments, whereby the Atlantic Meridional Overturning Circulation (AMOC) is interrupted by an injection of freshwater to the North Atlantic: if some, or all, abrupt climate change was not driven by freshwater input, could its character have been very different than the typical hosed experiments? Here, we describe spontaneous, unhosed oscillations in AMOC strength that occur in a global coupled ocean-atmosphere model when integrated under a particular background climate state. We compare these unhosed oscillations to hosed oscillations under a range of background climate states in order to examine how the global imprint of AMOC variations depends on whether or not they result from external freshwater input. Our comparison includes surface air temperature, precipitation, dissolved oxygen concentrations in the intermediate-depth ocean, and marine export production. The results show that the background climate state has a significant impact on the character of the freshwater-forced AMOC interruptions in this model, with particularly marked variations in tropical precipitation and in the North Pacific circulation. Despite these differences, the first-order patterns of response to AMOC interruptions are quite consistent among all simulations, implying that the ocean-sea ice-atmosphere dynamics associated with an AMOC weakening dominate the global response, regardless of whether or not freshwater input is the cause. Nonetheless, freshwater addition leads to a more complete shutdown of the AMOC than occurs in the unhosed oscillations, with amplified global impacts, evocative of Heinrich stadials. In addition, freshwater inputs can directly impact the strength of other polar haloclines, particularly that of the Southern Ocean, to which freshwater can be transported relatively quickly after injection in the North Atlantic. © Author(s) 2016. CC Attribution 3.0 License. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49081
Appears in Collections: 气候变化与战略
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Recommended Citation:
Brown N.,Galbraith E.D.. Hosed vs. unhosed: Interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing[J]. Climate of the Past,2016-01-01,12(8)