On dynamically unresolved oceanic mesoscale motions
File(s)
Published version
Author(s)
Berloff, Pavel
Ryzhov, Evgeny
Shevchenko, Igor
Type
Journal Article
Abstract
The problem of defining oceanic mesoscale eddies remains generally unresolved because there is no unique local spatio-temporal filter that can be used for extracting the eddies, and it is unclear what part of the eddy field cannot be actually resolved and needs to be parameterized in a coarse-grid model. We propose using of the coarse-grid model itself for reconstructing dynamically unresolved eddies, which are actually field errors on the top of the dynamically resolved, large-scale reference flow. The novelties and strengths of the approach are that (i) no spatio-temporal filtering is ever needed, (ii) field errors are dynamically translated into the error-correcting forcing and (iii) the latter exactly augments the coarse-grid model solution towards the reference flow. After implementation of the proposed approach, we study statistical properties of the field errors, show their robustness and reveal their significant differences from the locally filtered eddies. We argue that dynamical effects of unresolved eddies can be ultimately parameterized by emulating field errors and closing them on the dynamically resolved flow. So far, our results are limited to the quasigeostrophic approximation, but this serves as a proof of concept and starting point for the follow-up extension into the primitive equations, which are used routinely in the comprehensive oceanic general circulation models.
Date Issued
2021-08-10
Date Acceptance
2021-06-01
Citation
Journal of Fluid Mechanics, 2021, 920, pp.1-24
ISSN
0022-1120
Publisher
Cambridge University Press (CUP)
Start Page
1
End Page
24
Journal / Book Title
Journal of Fluid Mechanics
Volume
920
Copyright Statement
© The Author(s), 2021. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
License URL
Sponsor
Natural Environment Research Council (NERC)
The Leverhulme Trust
Natural Environment Research Council (NERC)
Natural Environment Research Council (NERC)
Identifier
https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/on-dynamically-unresolved-oceanic-mesoscale-motions/1429DA8FB09B0B74E4EC1A781E3719B5
Grant Number
NE/R011567/1
RPG-2019-024
NE/T002220/1
EP/V520354/1
Subjects
Fluids & Plasmas
01 Mathematical Sciences
09 Engineering
Publication Status
Published
Article Number
A41
Date Publish Online
2021-06-14