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Controls on the strength and structure of the Atlantic meridional overturning circulation in climate models
  • +1
  • Manali Nayak,
  • David Bonan,
  • Emily Rose Newsom,
  • Andrew F. Thompson
Manali Nayak
University of Washington

Corresponding Author:[email protected]

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David Bonan
California Institute of Technology
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Emily Rose Newsom
New York University
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Andrew F. Thompson
California Institute of Technology
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State-of-the-art climate models simulate a large spread in the mean-state Atlantic meridional overturning circulation (AMOC), with strengths varying between 12 and 25 Sv. Here, we introduce a framework for understanding this spread by assessing the balance between the thermal-wind expression and surface water mass transformation in the North Atlantic. The intermodel spread in the mean-state AMOC strength is shown to be related to the overturning scale depth: climate models with a larger scale depth tend to also have a stronger AMOC. Intermodel variations in the overturning scale depth are also related to intermodel variations in North Atlantic surface buoyancy loss and stratification. We present a physically-motivated scaling relationship that links the scale-depth variations to buoyancy forcing and stratification in the North Atlantic, and thus connects North Atlantic surface processes to the interior ocean circulation. These results offer a framework for reducing mean-state AMOC biases in climate models.
01 Mar 2024Submitted to ESS Open Archive
04 Mar 2024Published in ESS Open Archive