Sensitivity of the Antarctic Circumpolar Current transport to surface buoyancy conditions in the North Atlantic

TitleSensitivity of the Antarctic Circumpolar Current transport to surface buoyancy conditions in the North Atlantic
Publication TypeJournal Article
Year of Publication2017
AuthorsSun S.T, Liu J.L
JournalOcean Modelling
Volume118
Pagination118-129
Date Published2017/10
Type of ArticleArticle
ISBN Number1463-5003
Accession NumberWOS:000411466900009
Keywordsantarctic circumpolar current; climate-change; closure; drake passage; Meridional overturning circulation; models; North Atlantic; overturning circulation; sets; southern-ocean; stratification
Abstract

The sensitivity of the Antarctic Circumpolar Current (ACC) transport to surface buoyancy conditions in the North Atlantic is investigated using a sector configuration of an ocean general circulation model. We find that the sensitivity of the ACC transport is significantly weaker than previous studies. We attribute this difference to the different depth of the simulated Atlantic Meridional Overturning Circulation. Because a fast restoring buoyancy boundary condition is used that strongly constrains the surface buoyancy structure at the Southern Ocean surface, the ACC transport is determined by the isopycnal slope that is coupled to the overturning circulation in the Southern Ocean. By changing the surface buoyancy in the North Atlantic, the shared buoyancy contour between the North Atlantic and the Southern Ocean is varied, and consequently the strength of the overturning circulation is modified. For different depth of the simulated overturning circulation, the response of the ACC transport to changes in the strength of the overturning circulation varies substantially. This is illustrated in two conceptual models based on the residual-mean theory of overturning circulation. Our results imply that the sensitivity of the ACC transport to surface forcing in the North Atlantic could vary substantially in different models depending on the simulated vertical structure of the overturning circulation. (C) 2017 Elsevier Ltd. All rights reserved.

DOI10.1016/j.ocemod.2017.09.004
Short TitleOcean Model.
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