This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1175/JPO-D-21-0217.1. This is version 2 of this Preprint.
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Abstract
Mesoscale eddies, the weather system of the oceans, although being on the scales of O(20-100 km), have a disproportionate role in shaping the mean stratification, which varies on the scale of O(1000 km). With the increase in computational power, we are now able to partially resolve the eddies in basin-scale and global ocean simulations, a model resolution often referred to as mesoscale permitting. It is well known, however, that due to grid-scale numerical viscosity, mesoscale-permitting simulations have less energetic eddies and consequently weaker eddy feedback onto the mean flow. In this study, we run a quasi-geostrophic model at mesoscale-resolving resolution in a double gyre configuration and formulate a deterministic closure for the eddy rectification term of potential vorticity (PV), namely, the eddy PV flux divergence. Our closure successfully reproduces the spatial patterns and magnitude of eddy kinetic and potential energy diagnosed from the mesoscale-resolving model. One novel point about our approach is that we account for non-local eddy feedbacks onto the mean flow by solving the `sub-grid' eddy PV equation prognostically in addition to the mean PV.
DOI
https://doi.org/10.31223/X5WP71
Subjects
Physical Sciences and Mathematics
Keywords
Quasi-geostrophy, Mesoscale eddy closure
Dates
Published: 2021-09-29 04:54
Last Updated: 2021-12-15 14:58
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