North Atlantic weather regimes response to Indian-western Pacific Ocean warming: A multi-model study.

SanchezGomez, E., Cassou, C., Hodson, D. L. R., Keenlyside, Noel, Okmura, Y. and Zhou, T. (2008) North Atlantic weather regimes response to Indian-western Pacific Ocean warming: A multi-model study. Open Access Geophysical Research Letters, 35 (15). L15706. DOI 10.1029/2008GL034345.

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Abstract

The extratropical large-scale atmospheric circulation is often described in terms of a few preferred and recurrent patterns referred to as weather regimes. Here, we investigate the influence of the observed Indian and western Pacific Ocean (IP) warming over the last decades, on the frequency of occurrence of North Atlantic weather regimes. A multi-model approach is adopted in which five different atmospheric general circulation models are forced with idealized sea surface temperature patterns mimicking the IP warming. Despite some discrepancies, three models suggest a stronger occurrence of the Zonal regime when IP is warm, compensated by less frequent Greenland Anticyclone regimes, consistently with the observed positive trend of the North Atlantic Oscillation. The other two models simulate instead an increase in the frequency of occurrence of the Atlantic Ridge regime. Variance decomposition into stationary and transient waves suggest two mechanisms at work in the individual models. The AR regime favoured occurrence is associated with a strong transient wave activity along the wave guide in the North Pacific and downstream in the North Atlantic. The Zonal favoured excitation is interpreted as an indirect response to changes in the Tropical Atlantic associated with a global alteration of the Walker cell.

Document Type: Article
Keywords: North Atlantic Weather Regimes, North Atlantic Oscillation, Tropical extra-tropical interactions, Indian Ocean - Western Pacific warming, weather regime; Indo-Pacific warming; multi-model
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Refereed: Yes
Open Access Journal?: No
Publisher: AGU (American Geophysical Union)
Projects: DYNAMITE
Date Deposited: 05 Dec 2008 12:21
Last Modified: 08 Nov 2017 10:45
URI: https://oceanrep.geomar.de/id/eprint/7321

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