| DOI: | 10.1007/s00382-017-3957-6
|
| Scopus记录号: | 2-s2.0-85037722972
|
| 论文题名: | Timescales of AMOC decline in response to fresh water forcing |
| 作者: | Jackson L.C.; Wood R.A.
|
| 刊名: | Climate Dynamics
|
| ISSN: | 9307575
|
| 出版年: | 2018
|
| 卷: | 51, 期:4 | | 起始页码: | 1333
|
| 结束页码: | 1350
|
| 语种: | 英语
|
| 英文关键词: | AMOC
; Climate
; Timescale
|
| Scopus关键词: | Atlantic Multidecadal Oscillation
; atmospheric circulation
; climate change
; large eddy simulation
; meridional circulation
; timescale
|
| 英文摘要: | The Atlantic meridional overturning circulation (AMOC) is predicted to weaken over the coming century due to warming from greenhouse gases and increased input of fresh water into the North Atlantic, however there is considerable uncertainty as to the amount and rate of AMOC weakening. Understanding what controls the rate and timescale of AMOC weakening may help to reduce this uncertainty and hence reduce the uncertainty surrounding associated impacts. As a first step towards this we consider the timescales associated with weakening in response to idealized freshening scenarios. Here we explore timescales of AMOC weakening in response to a freshening of the North Atlantic in a suite of experiments with an eddy-permitting global climate model (GCM). When the rate of fresh water added to the North Atlantic is small (0.1 Sv; 1 Sv = 1 × 10 6 m3/s), the timescale of AMOC weakening depends mainly on the rate of fresh water input itself and can be longer than a century. When the rate of fresh water added is large (≥ 0.3 Sv) however, the timescale is a few decades and is insensitive to the actual rate of fresh water input. This insensitivity is because with a greater rate of fresh water input the advective feedbacks become more important at exporting fresh anomalies, so the rate of freshening is similar. We find advective feedbacks from: an export of fresh anomalies by the mean flow; less volume import through the Bering Strait; a weakening AMOC transporting less subtropical water northwards; and anomalous subtropical circulations which amplify export of the fresh anomalies. This latter circulation change is driven itself by the presence of fresh anomalies exported from the subpolar gyre through geostrophy. This feedback has not been identified in previous model studies and when the rate of freshening is strong it is found to dominate the total export of fresh anomalies, and hence the timescale of AMOC decline. Although results may be model dependent, qualitatively similar mechanisms are also found in a single experiment with a different GCM. © 2017, © Crown Copyright. |
| Citation statistics: |
|
| 资源类型: | 期刊论文
|
| 标识符: | http://119.78.100.158/handle/2HF3EXSE/109192
|
| Appears in Collections: | 影响、适应和脆弱性
气候变化事实与影响
|
|
There are no files associated with this item.
|
|
作者单位: | Met Office Hadley Centre, Exeter, United Kingdom
|
| Recommended Citation: | |
Jackson L.C.,Wood R.A.. Timescales of AMOC decline in response to fresh water forcing[J]. Climate Dynamics,2018-01-01,51(4)
|
|
|