The University of Southampton
University of Southampton Institutional Repository

Modeling the interplay between sea ice formation and the oceanic mixed layer: Limitations of simple brine rejection parameterizations

Modeling the interplay between sea ice formation and the oceanic mixed layer: Limitations of simple brine rejection parameterizations
Modeling the interplay between sea ice formation and the oceanic mixed layer: Limitations of simple brine rejection parameterizations
The subtle interplay between sea ice formation and ocean vertical mixing is hardly represented in current large-scale models designed for climate studies. Convective mixing caused by the brine release when ice forms is likely to prevail in leads and thin ice areas, while it occurs in models at the much larger horizontal grid cell scale. Subgrid-scale parameterizations have hence been developed to mimic the effects of small-scale convection using a vertical distribution of the salt rejected by sea ice within the mixed layer, instead of releasing it in the top ocean layer. Such a brine rejection parameterization is included in the global ocean–sea ice model NEMO-LIM3. Impacts on the simulated mixed layers and ocean temperature and salinity profiles, along with feedbacks on the sea ice cover, are then investigated in both hemispheres. The changes are overall relatively weak, except for mixed layer depths, which are in general excessively reduced compared to observation-based estimates. While potential model biases prevent a definitive attribution of this vertical mixing underestimation to the brine rejection parameterization, it is unlikely that the latter can be applied in all conditions. In that case, salt rejections do not play any role in mixed layer deepening, which is unrealistic. Applying the parameterization only for low ice–ocean relative velocities improves model results, but introduces additional parameters that are not well constrained by observations.
Model, Brine rejection, Parameterization, Ocean mixed layer, Arctic, Antarctic
1463-5003
141-152
Barthélemy, Antoine
e063bff5-5482-41fe-8abd-674a4a161502
Fichefet, Thierry
7b3028c8-1af9-4671-b041-51022a13bf73
Goosse, Hugues
33c33c55-356b-48ec-be78-3e9eb5d04f29
Madec, Gurvan
ffb28deb-4bbd-4a4c-914f-492f813e4864
Barthélemy, Antoine
e063bff5-5482-41fe-8abd-674a4a161502
Fichefet, Thierry
7b3028c8-1af9-4671-b041-51022a13bf73
Goosse, Hugues
33c33c55-356b-48ec-be78-3e9eb5d04f29
Madec, Gurvan
ffb28deb-4bbd-4a4c-914f-492f813e4864

Barthélemy, Antoine, Fichefet, Thierry, Goosse, Hugues and Madec, Gurvan (2015) Modeling the interplay between sea ice formation and the oceanic mixed layer: Limitations of simple brine rejection parameterizations. Ocean Modelling, 86, 141-152. (doi:10.1016/j.ocemod.2014.12.009).

Record type: Article

Abstract

The subtle interplay between sea ice formation and ocean vertical mixing is hardly represented in current large-scale models designed for climate studies. Convective mixing caused by the brine release when ice forms is likely to prevail in leads and thin ice areas, while it occurs in models at the much larger horizontal grid cell scale. Subgrid-scale parameterizations have hence been developed to mimic the effects of small-scale convection using a vertical distribution of the salt rejected by sea ice within the mixed layer, instead of releasing it in the top ocean layer. Such a brine rejection parameterization is included in the global ocean–sea ice model NEMO-LIM3. Impacts on the simulated mixed layers and ocean temperature and salinity profiles, along with feedbacks on the sea ice cover, are then investigated in both hemispheres. The changes are overall relatively weak, except for mixed layer depths, which are in general excessively reduced compared to observation-based estimates. While potential model biases prevent a definitive attribution of this vertical mixing underestimation to the brine rejection parameterization, it is unlikely that the latter can be applied in all conditions. In that case, salt rejections do not play any role in mixed layer deepening, which is unrealistic. Applying the parameterization only for low ice–ocean relative velocities improves model results, but introduces additional parameters that are not well constrained by observations.

This record has no associated files available for download.

More information

Published date: February 2015
Keywords: Model, Brine rejection, Parameterization, Ocean mixed layer, Arctic, Antarctic
Organisations: Marine Systems Modelling

Identifiers

Local EPrints ID: 374890
URI: http://eprints.soton.ac.uk/id/eprint/374890
ISSN: 1463-5003
PURE UUID: 6f500bb5-4ff8-4e58-b77d-12a28af93d2a

Catalogue record

Date deposited: 04 Mar 2015 17:01
Last modified: 14 Mar 2024 19:16

Export record

Altmetrics

Contributors

Author: Antoine Barthélemy
Author: Thierry Fichefet
Author: Hugues Goosse
Author: Gurvan Madec

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.

×