The University of Southampton
University of Southampton Institutional Repository

Internal lee wave closures: Parameter sensitivity and comparison to observations

Internal lee wave closures: Parameter sensitivity and comparison to observations
Internal lee wave closures: Parameter sensitivity and comparison to observations
This paper examines two internal lee wave closures that have been used together with ocean models to predict the time-averaged global energy conversion rate into lee waves and dissipation rate associated with lee waves and topographic blocking: the Garner (2005) scheme and the Bell (1975) theory. The closure predictions in two Southern Ocean regions where geostrophic flows dominate over tides are examined and compared to microstructure profiler observations of the turbulent kinetic energy dissipation rate, where the latter are assumed to reflect the dissipation associated with topographic blocking and generated lee wave energy. It is shown that when applied to these Southern Ocean regions, the two closures differ most in their treatment of topographic blocking. For several reasons, pointwise validation of the closures is not possible using existing observations, but horizontally averaged comparisons between closure predictions and observations are made. When anisotropy of the underlying topography is accounted for, the two horizontally averaged closure predictions near the seafloor are approximately equal. The dissipation associated with topographic blocking is predicted by the Garner (2005) scheme to account for the majority of the depth-integrated dissipation over the bottom 1000 m of the water column, where the horizontally averaged predictions lie well within the spatial variability of the horizontally averaged observations. Simplifications made by the Garner (2005) scheme that are inappropriate for the oceanic context, together with imperfect observational information, can partially account for the prediction-observation disagreement, particularly in the upper water column.
mixing, dissipation, finestructure, internal waves, topographic interactions, microstructure
2169-9275
7997-8019
Trossman, D.S.
6a87bd8a-6149-456a-8204-aa543d4fddb4
Waterman, S.
3283414a-1681-4328-9cb0-9b5209fb5b45
Polzin, K.L.
a6ad08a3-7577-4b70-9db7-65926301df6f
Arbic, B.K.
a0db413b-8cb6-4a0d-ae25-6739db8fc5ec
Garner, S.T.
0293263f-f831-4bf8-94f2-ce643093fa9e
Naveira-Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Sheen, K.L.
11fc9ce4-1a9a-4925-ae04-816e5e8660ae
Trossman, D.S.
6a87bd8a-6149-456a-8204-aa543d4fddb4
Waterman, S.
3283414a-1681-4328-9cb0-9b5209fb5b45
Polzin, K.L.
a6ad08a3-7577-4b70-9db7-65926301df6f
Arbic, B.K.
a0db413b-8cb6-4a0d-ae25-6739db8fc5ec
Garner, S.T.
0293263f-f831-4bf8-94f2-ce643093fa9e
Naveira-Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Sheen, K.L.
11fc9ce4-1a9a-4925-ae04-816e5e8660ae

Trossman, D.S., Waterman, S., Polzin, K.L., Arbic, B.K., Garner, S.T., Naveira-Garabato, A.C. and Sheen, K.L. (2015) Internal lee wave closures: Parameter sensitivity and comparison to observations. Journal of Geophysical Research: Oceans, 120 (12), 7997-8019. (doi:10.1002/2015JC010892).

Record type: Article

Abstract

This paper examines two internal lee wave closures that have been used together with ocean models to predict the time-averaged global energy conversion rate into lee waves and dissipation rate associated with lee waves and topographic blocking: the Garner (2005) scheme and the Bell (1975) theory. The closure predictions in two Southern Ocean regions where geostrophic flows dominate over tides are examined and compared to microstructure profiler observations of the turbulent kinetic energy dissipation rate, where the latter are assumed to reflect the dissipation associated with topographic blocking and generated lee wave energy. It is shown that when applied to these Southern Ocean regions, the two closures differ most in their treatment of topographic blocking. For several reasons, pointwise validation of the closures is not possible using existing observations, but horizontally averaged comparisons between closure predictions and observations are made. When anisotropy of the underlying topography is accounted for, the two horizontally averaged closure predictions near the seafloor are approximately equal. The dissipation associated with topographic blocking is predicted by the Garner (2005) scheme to account for the majority of the depth-integrated dissipation over the bottom 1000 m of the water column, where the horizontally averaged predictions lie well within the spatial variability of the horizontally averaged observations. Simplifications made by the Garner (2005) scheme that are inappropriate for the oceanic context, together with imperfect observational information, can partially account for the prediction-observation disagreement, particularly in the upper water column.

Text
Trossman_et_al-2015-Journal_of_Geophysical_Research__Oceans.pdf - Version of Record
Download (1MB)

More information

Accepted/In Press date: 15 November 2015
Published date: 17 December 2015
Keywords: mixing, dissipation, finestructure, internal waves, topographic interactions, microstructure
Organisations: Physical Oceanography

Identifiers

Local EPrints ID: 385214
URI: http://eprints.soton.ac.uk/id/eprint/385214
ISSN: 2169-9275
PURE UUID: e8c2064e-8b33-4db5-8dc5-376c43d9200f
ORCID for A.C. Naveira-Garabato: ORCID iD orcid.org/0000-0001-6071-605X

Catalogue record

Date deposited: 18 Dec 2015 10:45
Last modified: 15 Mar 2024 03:24

Export record

Altmetrics

Contributors

Author: D.S. Trossman
Author: S. Waterman
Author: K.L. Polzin
Author: B.K. Arbic
Author: S.T. Garner
Author: K.L. Sheen

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×