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Decadal-timescale changes of the Atlantic overturning circulation and climate in a coupled climate model with a hybrid-coordinate ocean component

Decadal-timescale changes of the Atlantic overturning circulation and climate in a coupled climate model with a hybrid-coordinate ocean component
Decadal-timescale changes of the Atlantic overturning circulation and climate in a coupled climate model with a hybrid-coordinate ocean component
A wide range of statistical tools is used to investigate the decadal variability of the Atlantic Meridional Overturning Circulation (AMOC) and associated key variables in a climate model (CHIME, Coupled Hadley-Isopycnic Model Experiment), which features a novel ocean component. CHIME is as similar as possible to the 3rd Hadley Centre Coupled Model (HadCM3) with the important exception that its ocean component is based on a hybrid vertical coordinate. Power spectral analysis reveals enhanced AMOC variability for periods in the range 15–30 years. Strong AMOC conditions are associated with: (1) a Sea Surface Temperature (SST) anomaly pattern reminiscent of the Atlantic Multi-decadal Oscillation (AMO) response, but associated with variations in a northern tropical-subtropical gradient; (2) a Surface Air Temperature anomaly pattern closely linked to SST; (3) a positive North Atlantic Oscillation (NAO)-like pattern; (4) a northward shift of the Intertropical Convergence Zone. The primary mode of AMOC variability is associated with decadal changes in the Labrador Sea and the Greenland Iceland Norwegian (GIN) Seas, in both cases linked to the tropical activity about 15 years earlier. These decadal changes are controlled by the low-frequency NAO that may be associated with a rapid atmospheric teleconnection from the tropics to the extratropics. Poleward advection of salinity anomalies in the mixed layer also leads to AMOC changes that are linked to processes in the Labrador Sea. A secondary mode of AMOC variability is associated with interannual changes in the Labrador and GIN Seas, through the impact of the NAO on local surface density.
Atlantic Meridional Overturning Circulation, North Atlantic Oscillation, Coupled climate model, Isopycnal, Decadal variability
0930-7575
1021-1042
Persechino, A.
516687cb-440c-4cc3-91e9-21233b28ae04
Marsh, R.
702c2e7e-ac19-4019-abd9-a8614ab27717
Sinha, B.
544b5a07-3d74-464b-9470-a68c69bd722e
Megann, A.P.
4fd92e77-5512-487d-bb28-8476afafdeaf
Blaker, A.T.
94efe8b2-c744-4e90-87d7-db19ffa41200
New, A.L.
69c2be8b-c6c2-408f-9612-6980b1a25802
Persechino, A.
516687cb-440c-4cc3-91e9-21233b28ae04
Marsh, R.
702c2e7e-ac19-4019-abd9-a8614ab27717
Sinha, B.
544b5a07-3d74-464b-9470-a68c69bd722e
Megann, A.P.
4fd92e77-5512-487d-bb28-8476afafdeaf
Blaker, A.T.
94efe8b2-c744-4e90-87d7-db19ffa41200
New, A.L.
69c2be8b-c6c2-408f-9612-6980b1a25802

Persechino, A., Marsh, R., Sinha, B., Megann, A.P., Blaker, A.T. and New, A.L. (2012) Decadal-timescale changes of the Atlantic overturning circulation and climate in a coupled climate model with a hybrid-coordinate ocean component. Climate Dynamics, 39 (3-4), 1021-1042. (doi:10.1007/s00382-012-1432-y).

Record type: Article

Abstract

A wide range of statistical tools is used to investigate the decadal variability of the Atlantic Meridional Overturning Circulation (AMOC) and associated key variables in a climate model (CHIME, Coupled Hadley-Isopycnic Model Experiment), which features a novel ocean component. CHIME is as similar as possible to the 3rd Hadley Centre Coupled Model (HadCM3) with the important exception that its ocean component is based on a hybrid vertical coordinate. Power spectral analysis reveals enhanced AMOC variability for periods in the range 15–30 years. Strong AMOC conditions are associated with: (1) a Sea Surface Temperature (SST) anomaly pattern reminiscent of the Atlantic Multi-decadal Oscillation (AMO) response, but associated with variations in a northern tropical-subtropical gradient; (2) a Surface Air Temperature anomaly pattern closely linked to SST; (3) a positive North Atlantic Oscillation (NAO)-like pattern; (4) a northward shift of the Intertropical Convergence Zone. The primary mode of AMOC variability is associated with decadal changes in the Labrador Sea and the Greenland Iceland Norwegian (GIN) Seas, in both cases linked to the tropical activity about 15 years earlier. These decadal changes are controlled by the low-frequency NAO that may be associated with a rapid atmospheric teleconnection from the tropics to the extratropics. Poleward advection of salinity anomalies in the mixed layer also leads to AMOC changes that are linked to processes in the Labrador Sea. A secondary mode of AMOC variability is associated with interannual changes in the Labrador and GIN Seas, through the impact of the NAO on local surface density.

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More information

Published date: 2012
Keywords: Atlantic Meridional Overturning Circulation, North Atlantic Oscillation, Coupled climate model, Isopycnal, Decadal variability
Organisations: Marine Systems Modelling, Physical Oceanography

Identifiers

Local EPrints ID: 342786
URI: https://eprints.soton.ac.uk/id/eprint/342786
ISSN: 0930-7575
PURE UUID: 3e444b39-1ec9-4ba4-9d94-029457e3e555

Catalogue record

Date deposited: 13 Sep 2012 09:40
Last modified: 18 Jul 2017 05:27

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