The University of Southampton
University of Southampton Institutional Repository

Causes of interannual-decadal variability in the meridional overturning circulation of the mid-latitude North Atlantic Ocean

Causes of interannual-decadal variability in the meridional overturning circulation of the mid-latitude North Atlantic Ocean
Causes of interannual-decadal variability in the meridional overturning circulation of the mid-latitude North Atlantic Ocean
The causes and characteristics of interannual to decadal variability of the meridional overturning circulation (MOC) in the North Atlantic are investigated with a suite of basin-scale ocean models (FLAME) and global ocean-ice models (ORCA) varying in resolution from medium- to eddy-resolving (1/2° – 1/12°), using various forcing configurations built on bulk formulations invoking atmospheric reanalysis products. Comparison of the model hindcasts indicates similar MOC variability characteristics on time scales up to a decade; both model architectures also simulate an upward trend in MOC strength between the early 1970s and mid-1990s. The causes of the MOC changes are examined by perturbation experiments aimed selectively at the response to individual forcing components. The solutions emphasize an inherently linear character of the mid-latitude MOC variability by demonstrating that the anomalies of a (non eddy-resolving) hind-cast simulation can be understood as a superposition of decadal and longer-term signals originating from thermohaline forcing variability, and a higher-frequency wind-driven variability. The thermohaline MOC signal is linked to the variability in subarctic deep water formation, and rapidly progressing to the tropical Atlantic. However, throughout the subtropical and mid-latitude North Atlantic this signal is effectively masked by stronger MOC variability related to wind forcing and, especially north of 30–35° N, by internally-induced (eddy) fluctuations.
0894-8755
6599-6615
Biastoch, Arne
aded5e89-c706-49e6-bed2-eb41259f7b57
Böning, Claus W.
b724a76f-0dd9-440d-91ce-779f4e7501b7
Getzlaff, Julia
942892a6-174c-40c2-a0f2-9444966d8258
Molines, Jean-Marc
ff0e29c2-d4e8-4c72-995c-6e53801d823f
Madec, Gurvan
ffb28deb-4bbd-4a4c-914f-492f813e4864
Biastoch, Arne
aded5e89-c706-49e6-bed2-eb41259f7b57
Böning, Claus W.
b724a76f-0dd9-440d-91ce-779f4e7501b7
Getzlaff, Julia
942892a6-174c-40c2-a0f2-9444966d8258
Molines, Jean-Marc
ff0e29c2-d4e8-4c72-995c-6e53801d823f
Madec, Gurvan
ffb28deb-4bbd-4a4c-914f-492f813e4864

Biastoch, Arne, Böning, Claus W., Getzlaff, Julia, Molines, Jean-Marc and Madec, Gurvan (2008) Causes of interannual-decadal variability in the meridional overturning circulation of the mid-latitude North Atlantic Ocean. Journal of Climate, 21 (24), 6599-6615. (doi:10.1175/2008JCLI2404.1).

Record type: Article

Abstract

The causes and characteristics of interannual to decadal variability of the meridional overturning circulation (MOC) in the North Atlantic are investigated with a suite of basin-scale ocean models (FLAME) and global ocean-ice models (ORCA) varying in resolution from medium- to eddy-resolving (1/2° – 1/12°), using various forcing configurations built on bulk formulations invoking atmospheric reanalysis products. Comparison of the model hindcasts indicates similar MOC variability characteristics on time scales up to a decade; both model architectures also simulate an upward trend in MOC strength between the early 1970s and mid-1990s. The causes of the MOC changes are examined by perturbation experiments aimed selectively at the response to individual forcing components. The solutions emphasize an inherently linear character of the mid-latitude MOC variability by demonstrating that the anomalies of a (non eddy-resolving) hind-cast simulation can be understood as a superposition of decadal and longer-term signals originating from thermohaline forcing variability, and a higher-frequency wind-driven variability. The thermohaline MOC signal is linked to the variability in subarctic deep water formation, and rapidly progressing to the tropical Atlantic. However, throughout the subtropical and mid-latitude North Atlantic this signal is effectively masked by stronger MOC variability related to wind forcing and, especially north of 30–35° N, by internally-induced (eddy) fluctuations.

This record has no associated files available for download.

More information

Published date: December 2008

Identifiers

Local EPrints ID: 64312
URI: http://eprints.soton.ac.uk/id/eprint/64312
ISSN: 0894-8755
PURE UUID: 762fad95-9d4d-474d-8865-f4f093abc3d3

Catalogue record

Date deposited: 09 Dec 2008
Last modified: 15 Mar 2024 11:47

Export record

Altmetrics

Contributors

Author: Arne Biastoch
Author: Claus W. Böning
Author: Julia Getzlaff
Author: Jean-Marc Molines
Author: Gurvan Madec

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×