Nonlinear Climate Responses to Changes in Antarctic Intermediate Water

Graham, Jennifer A., Stevens, David P. and Heywood, Karen J. (2013) Nonlinear Climate Responses to Changes in Antarctic Intermediate Water. Journal of Climate, 26 (22). pp. 9175-9193. ISSN 0894-8755

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Abstract

The global impact of changes in Antarctic Intermediate Water (AAIW) properties is demonstrated using idealized perturbation experiments in a coupled climate model. Properties of AAIW were altered between 10° and 20°S in the Atlantic, Pacific, and Indian Oceans separately. Potential temperature was changed by ±1°C, along with density-compensating changes in salinity. For each of the experiments, sea surface temperature responds to changes in AAIW when anomalies surface at higher latitudes (>30°). Anomalous sea-to-air heat fluxes leave density anomalies in the ocean, resulting in nonlinear responses to opposite-sign perturbations. In the Southern Ocean, these affect the meridional density gradient, leading to changes in Antarctic Circumpolar Current transport. The response to cooler, fresher AAIW is both greater in magnitude and significant over a larger area than that for warmer, saltier AAIW. The North Atlantic is particularly sensitive to cool, fresh perturbations, with density anomalies causing reductions in the meridional overturning circulation of up to 1 Sv (1 Sv = 106 m3 s-1). Resultant changes in meridional ocean heat transport, along with surfacing anomalies, cause basinwide changes in the surface ocean and overlying atmosphere on multidecadal time scales.

Item Type: Article
Uncontrolled Keywords: water masses,climate prediction,climate models,climate variability
Faculty \ School: Faculty of Science > School of Environmental Sciences
Faculty of Science > School of Mathematics
Related URLs:
Depositing User: Pure Connector
Date Deposited: 04 Nov 2013 22:10
Last Modified: 26 Jul 2020 23:34
URI: https://ueaeprints.uea.ac.uk/id/eprint/44217
DOI: 10.1175/JCLI-D-12-00767.1

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