Stable AMOC off state in an eddy-permitting coupled climate model
Stable AMOC off state in an eddy-permitting coupled climate model
Shifts between on and off states of the Atlantic Meridional Overturning Circulation (AMOC) have been associated with past abrupt climate change, supported by the bistability of the AMOC found in many older, coarser resolution, ocean and climate models. However, as coupled climate models evolved in complexity a stable AMOC off state no longer seemed supported. Here we show that a current-generation, eddy-permitting climate model has an AMOC off state that remains stable for the 450-year duration of the model integration. Ocean eddies modify the overall freshwater balance, allowing for stronger northward salt transport by the AMOC compared with previous, non eddy-permitting models. As a result, the salinification of the subtropical North Atlantic, due to a southward shift of the intertropical rain belt, is counteracted by the reduced salt transport of the collapsed AMOC. The reduced salinification of the subtropical North Atlantic allows for an anomalous northward freshwater transport into the subpolar North Atlantic dominated by the gyre component. Combining the anomalous northward freshwater transport with the freshening due to reduced evaporation in this region helps stabilise the AMOC off state.
AMOC, AMOC collapse, Abrupt climate change, Hosing experiment, CGCM, Eddy-permitting
2455-2470
Mecking, Jennifer
9b090069-5061-4340-b736-9690894ce203
Drijfhout, Sybren
a5c76079-179b-490c-93fe-fc0391aacf13
Jackson, Laura
48fca1af-6cc5-4314-80b4-b21ad3245749
Graham, Tim
da80898b-86ac-4f1e-a91d-8ab7b16b14df
October 2016
Mecking, Jennifer
9b090069-5061-4340-b736-9690894ce203
Drijfhout, Sybren
a5c76079-179b-490c-93fe-fc0391aacf13
Jackson, Laura
48fca1af-6cc5-4314-80b4-b21ad3245749
Graham, Tim
da80898b-86ac-4f1e-a91d-8ab7b16b14df
Mecking, Jennifer, Drijfhout, Sybren, Jackson, Laura and Graham, Tim
(2016)
Stable AMOC off state in an eddy-permitting coupled climate model.
Climate Dynamics, 47 (7-8), .
(doi:10.1007/s00382-016-2975-0).
Abstract
Shifts between on and off states of the Atlantic Meridional Overturning Circulation (AMOC) have been associated with past abrupt climate change, supported by the bistability of the AMOC found in many older, coarser resolution, ocean and climate models. However, as coupled climate models evolved in complexity a stable AMOC off state no longer seemed supported. Here we show that a current-generation, eddy-permitting climate model has an AMOC off state that remains stable for the 450-year duration of the model integration. Ocean eddies modify the overall freshwater balance, allowing for stronger northward salt transport by the AMOC compared with previous, non eddy-permitting models. As a result, the salinification of the subtropical North Atlantic, due to a southward shift of the intertropical rain belt, is counteracted by the reduced salt transport of the collapsed AMOC. The reduced salinification of the subtropical North Atlantic allows for an anomalous northward freshwater transport into the subpolar North Atlantic dominated by the gyre component. Combining the anomalous northward freshwater transport with the freshening due to reduced evaporation in this region helps stabilise the AMOC off state.
Text
hosing_stability.pdf
- Accepted Manuscript
More information
Accepted/In Press date: 2 January 2016
e-pub ahead of print date: 30 January 2016
Published date: October 2016
Keywords:
AMOC, AMOC collapse, Abrupt climate change, Hosing experiment, CGCM, Eddy-permitting
Organisations:
Physical Oceanography, Paleooceanography & Palaeoclimate
Identifiers
Local EPrints ID: 402320
URI: http://eprints.soton.ac.uk/id/eprint/402320
ISSN: 0930-7575
PURE UUID: 2046c093-8e8d-4d6f-9ac5-37d008c6cc54
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Date deposited: 03 Nov 2016 14:02
Last modified: 15 Mar 2024 06:02
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Contributors
Author:
Jennifer Mecking
Author:
Laura Jackson
Author:
Tim Graham
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