Southern Annular Mode and westerly-wind-driven changes in Indian-Atlantic exchange mechanisms

Loveday, BR, Penven, P and Reason, CJC 2015 Southern Annular Mode and westerly-wind-driven changes in Indian-Atlantic exchange mechanisms. Geophysical Research Letters, 42 (12). 4912-4921. https://doi.org/10.1002/2015GL064256

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Abstract/Summary

The dynamical link between the Indian Ocean and Atlantic Meridional Overturning Circulation (AMOC) remains poorly understood. This partly arises from the complex Agulhas leakage, which occurs via rings, cyclones, and non-eddy flux. Hindcast simulations suggest that leakage has recently increased but have not decomposed this signal into its constituent mechanisms. Here these are isolated in a realistic ocean model. Increases in simulated leakage are attributed to stronger eddy and non-eddy-driven transports, and a strong warming and salinification, especially within Agulhas rings. Variability in both regimes is associated with strengthening Indian Ocean westerly winds, reflecting an increasingly positive Southern Annular Mode. While eddy and non-eddy flux signals are tied through turbulent eddy dissipation, the ratio between the two varies decadally. Consequently, while altimetry suggests a recent increase in retroflection turbulence and implied leakage, non-eddy flux may also play a significant role in modulating the leakage AMOC connection.

Item Type:	Publication - Article
Subjects:	Ecology and Environment Marine Sciences
Divisions:	Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User:	Dr Benjamin Loveday
Date made live:	26 Feb 2016 13:32
Last Modified:	06 Jun 2017 16:14
URI:	https://plymsea.ac.uk/id/eprint/6732

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