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Response of the South Atlantic circulation to an abrupt collapse of the Atlantic meridional overturning circulation

Response of the South Atlantic circulation to an abrupt collapse of the Atlantic meridional overturning circulation
Response of the South Atlantic circulation to an abrupt collapse of the Atlantic meridional overturning circulation
The South Atlantic response to a collapse of the North Atlantic meridional overturning circulation (AMOC) is investigated in the ECHAM5/MPI-OM climate model. A reduced Agulhas leakage (about 3.1 Sv; 1 Sv = 106 m3 s-1) is found to be associated with a weaker Southern Hemisphere (SH) supergyre and Indonesian throughflow. These changes are due to reduced wind stress curl over the SH supergyre, associated with a weaker Hadley circulation and a weaker SH subtropical jet. The northward cross-equatorial transport of thermocline and intermediate waters is much more strongly reduced than Agulhas leakage in relation with an AMOC collapse. A cross-equatorial gyre develops due to an anomalous wind stress curl over the tropics that results from the anomalous sea surface temperature gradient associated with reduced ocean heat transport. This cross-equatorial gyre completely blocks the transport of thermocline waters from the South to the North Atlantic. The waters originating from Agulhas leakage flow somewhat deeper and most of it recirculates in the South Atlantic subtropical gyre, leading to a gyre intensification. This intensification is consistent with the anomalous surface cooling over the South Atlantic. Most changes in South Atlantic circulation due to global warming, featuring a reduced AMOC, are qualitatively similar to the response to an AMOC collapse, but smaller in amplitude. However, the increased northward cross-equatorial transport of intermediate water relative to thermocline water is a strong fingerprint of an AMOC collapse.
0930-7575
521-530
Laurian, Audine
ec244691-e6aa-48bf-8391-3b47b9761739
Drijfhout, Sybren S.
a5c76079-179b-490c-93fe-fc0391aacf13
Laurian, Audine
ec244691-e6aa-48bf-8391-3b47b9761739
Drijfhout, Sybren S.
a5c76079-179b-490c-93fe-fc0391aacf13

Laurian, Audine and Drijfhout, Sybren S. (2011) Response of the South Atlantic circulation to an abrupt collapse of the Atlantic meridional overturning circulation. Climate Dynamics, 37 (3-4), 521-530. (doi:10.1007/s00382-010-0890-3).

Record type: Article

Abstract

The South Atlantic response to a collapse of the North Atlantic meridional overturning circulation (AMOC) is investigated in the ECHAM5/MPI-OM climate model. A reduced Agulhas leakage (about 3.1 Sv; 1 Sv = 106 m3 s-1) is found to be associated with a weaker Southern Hemisphere (SH) supergyre and Indonesian throughflow. These changes are due to reduced wind stress curl over the SH supergyre, associated with a weaker Hadley circulation and a weaker SH subtropical jet. The northward cross-equatorial transport of thermocline and intermediate waters is much more strongly reduced than Agulhas leakage in relation with an AMOC collapse. A cross-equatorial gyre develops due to an anomalous wind stress curl over the tropics that results from the anomalous sea surface temperature gradient associated with reduced ocean heat transport. This cross-equatorial gyre completely blocks the transport of thermocline waters from the South to the North Atlantic. The waters originating from Agulhas leakage flow somewhat deeper and most of it recirculates in the South Atlantic subtropical gyre, leading to a gyre intensification. This intensification is consistent with the anomalous surface cooling over the South Atlantic. Most changes in South Atlantic circulation due to global warming, featuring a reduced AMOC, are qualitatively similar to the response to an AMOC collapse, but smaller in amplitude. However, the increased northward cross-equatorial transport of intermediate water relative to thermocline water is a strong fingerprint of an AMOC collapse.

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Published date: August 2011
Organisations: Physical Oceanography

Identifiers

Local EPrints ID: 348362
URI: http://eprints.soton.ac.uk/id/eprint/348362
ISSN: 0930-7575
PURE UUID: bc0bfc68-1a92-4dd7-bf77-fdbc68654580
ORCID for Sybren S. Drijfhout: ORCID iD orcid.org/0000-0001-5325-7350

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Date deposited: 12 Feb 2013 13:10
Last modified: 15 Mar 2024 03:44

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Author: Audine Laurian

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