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Basin bifurcations, oscillatory instability and rate-induced thresholds for Atlantic meridional overturning circulation in a global oceanic box model

Citation

Alkhayuon, H and Ashwin, P and Jackson, LC and Quinn, C and Wood, RA, Basin bifurcations, oscillatory instability and rate-induced thresholds for Atlantic meridional overturning circulation in a global oceanic box model, Proceedings of the Royal Society A, 475, (2225) Article 20190051. ISSN 1364-5021 (2019) [Refereed Article]

Copyright Statement

2019 The Author(s) Published by the Royal Society. All rights reserved.

DOI: doi:10.1098/rspa.2019.0051

Abstract

The Atlantic meridional overturning circulation (AMOC) transports substantial amounts of heat into the North Atlantic sector, and hence is of very high importance in regional climate projections. The AMOC has been observed to show multi-stability across a range of models of different complexity. The simplest models find a bifurcation associated with the AMOC ‘on’ state losing stability that is a saddle node. Here, we study a physically derived global oceanic model of Wood et al. with five boxes, that is calibrated to runs of the FAMOUS coupled atmosphere-ocean general circulation model. We find the loss of stability of the ‘on’ state is due to a subcritical Hopf for parameters from both pre-industrial and doubled CO2 atmospheres. This loss of stability via subcritical Hopf bifurcation has important consequences for the behaviour of the basin of attraction close to bifurcation. We consider various time-dependent profiles of freshwater forcing to the system, and find that rate-induced thresholds for tipping can appear, even for perturbations that do not cross the bifurcation. Understanding how such state transitions occur is important in determining allowable safe climate change mitigation pathways to avoid collapse of the AMOC.

Item Details

Item Type:Refereed Article
Keywords:Atlantic meridional overturning circulation, rate-induced tipping point, ocean heat transport
Research Division:Mathematical Sciences
Research Group:Applied mathematics
Research Field:Dynamical systems in applications
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate variability (excl. social impacts)
UTAS Author:Quinn, C (Dr Courtney Quinn)
ID Code:149466
Year Published:2019
Web of Science® Times Cited:25
Deposited By:Mathematics
Deposited On:2022-03-31
Last Modified:2022-05-24
Downloads:0

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