A Unified Formulation of Quasi‐Geostrophic and Shallow Water Equations via Projection

Abstract This paper introduces a unified model for layered rotating shallow‐water (RSW) and quasi‐geostrophic (QG) equations, based on the intrinsic relationship between these two sets of equations. We propose a novel formulation of the QG equations as a projection of the RSW equations. This formula...

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Bibliographic Details
Main Authors: Louis Thiry, Long Li, Etienne Mémin, Guillaume Roullet
Format: Article
Language:English
Published: American Geophysical Union (AGU) 2024-10-01
Series:Journal of Advances in Modeling Earth Systems
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Online Access:https://doi.org/10.1029/2024MS004510
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Summary:Abstract This paper introduces a unified model for layered rotating shallow‐water (RSW) and quasi‐geostrophic (QG) equations, based on the intrinsic relationship between these two sets of equations. We propose a novel formulation of the QG equations as a projection of the RSW equations. This formulation uses the same prognostic variables as RSW, namely velocity and layer thickness, thereby restoring the proximity of these two sets of equations. It provides direct access to the ageostrophic velocities embedded within the geostrophic velocities resolved by the QG equations. This approach facilitates the study of differences between QG and RSW using a consistent numerical discretization. We demonstrate the effectiveness of this formulation through examples including vortex shear instability, double‐gyre circulation, and a simplified North Atlantic configuration.
ISSN:1942-2466