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Atmosphere drives recent interannual variability of the Atlantic meridional overturning circulation at 26.5°N

Roberts, C.D.; Waters, J.; Peterson, K.A.; Palmer, M.D.; McCarthy, G.D.; Frajka-Williams, E.; Haines, K.; Lea, D.J.; Martin, M.J.; Storkey, D.; Blockley, E.W.; Zuo, H.. 2013 Atmosphere drives recent interannual variability of the Atlantic meridional overturning circulation at 26.5°N. Geophysical Research Letters, 40 (19). 5164-5170. 10.1002/grl.50930

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Abstract/Summary

The Atlantic meridional overturning circulation (AMOC) has been observed at 26.5°N since 2004. During 2009/2010, there was a transient 30% weakening of the AMOC driven by anomalies in geostrophic and Ekman transports. Here, we use simulations based on the Met Office Forecast Ocean Assimilation Model (FOAM) to diagnose the relative importance of atmospheric forcings and internal ocean dynamics in driving the anomalous geostrophic circulation of 2009/2010. Data-assimilating experiments with FOAM accurately reproduce the mean strength and depth of the AMOC at 26.5°N. In addition, agreement between simulated and observed stream functions in the deep ocean is improved when we calculate the AMOC using a method that approximates the observing array at 26.5°N. The main features of the geostrophic circulation anomaly are captured by an ensemble of simulations without data assimilation. These model results suggest that the atmosphere played a dominant role in driving recent interannual variability of the AMOC.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1002/grl.50930
ISSN: 00948276
Additional Keywords: AMOC; variability; ocean model; data assimilation; ocean circulation; Atlantic meridional overturning circulation
Date made live: 20 Nov 2013 17:08 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/503954

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