Multiple Equilibria as a Possible Mechanism for Decadal Variability in the North Atlantic Ocean

Born, Andreas; Mignot, Juliette; Stocker, Thomas F. (2015). Multiple Equilibria as a Possible Mechanism for Decadal Variability in the North Atlantic Ocean. Journal of Climate, 28(22), pp. 8907-8922. American Meteorological Society 10.1175/JCLI-D-14-00813.1

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Decadal climate variability in the North Atlantic has received increased attention in recent years, because modeling results suggest predictability of heat content and circulation indices several years ahead. However, determining the applicability of these results in the real world is challenging because of an incomplete understanding of the underlying mechanisms. Here, the authors show that recent attempts to reconstruct the decadal variations in one of the dominant circulation systems of the region, the subpolar gyre (SPG), are not always consistent. A coherent picture is partly recovered by a simple conceptual model solely forced by reanalyzed surface air temperatures. This confirms that surface heat flux indeed plays a leading role for this type of variability, as has been suggested in previous studies. The results further suggest that large variations in the SPG correspond to the crossing of a bifurcation point that is predicted from idealized experiments and an analytical solution of the model used herein. Performance of this conceptual model is tested against a statistical stochastic model. Hysteresis and the existence of two stable modes of the SPG circulation shape its response to forcing by atmospheric temperatures. The identification of the essential dynamics and the reduction to a minimal model of SPG variability provide a quantifiable basis and a framework for future studies on decadal climate variability and predictability.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Physics Institute

UniBE Contributor:

Born, Andreas; Mignot, Juliette and Stocker, Thomas

Subjects:

500 Science > 530 Physics

ISSN:

0894-8755

Publisher:

American Meteorological Society

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

08 Dec 2015 10:10

Last Modified:

05 Dec 2022 14:50

Publisher DOI:

10.1175/JCLI-D-14-00813.1

BORIS DOI:

10.7892/boris.73874

URI:

https://boris.unibe.ch/id/eprint/73874

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