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Impact of surface waves on sea ice and ocean in the polar regions

Impact of surface waves on sea ice and ocean in the polar regions
Impact of surface waves on sea ice and ocean in the polar regions
Wave height in the Arctic is increasing and this is expected to continue as summer sea ice cover declines. The summer Marginal Ice Zone (MIZ), an area consisting of severely fragmented sea ice undergoing frequent collisions, is also expanding in the Arctic. Current climate and forecasting models are not adapted to simulate these conditions, yet accurate models are required because of climate change and the increasing human activity in the region. This project aims to improve such models by including wave-related processes that are currently lacking. A main focus is on sea ice rheology. A combined Collisional and Elastic-Viscous-Plastic (EVP) rheology is implemented in an idealised model configuration and in a global sea ice-ocean general circulation model. The combined rheology reflects both the granular behaviour of sea ice in the MIZ and the EVP rheology appropriate for pack ice conditions. This replaces the standard EVP rheology currently used in models. The effect of sea ice floe size, determined by wave break-up and thermodynamics, is also examined using a new floe size distribution (FSD) formulation. Finally, an existing wave mixing formulation is modied to use consistent wave information from the model rather than parameterisations. The combined rheology is found to be capable of maintaining a MIZ at high resolution in idealised simulations due to internal sea ice mechanisms only, while EVP is not. It also aaffects sea ice distribution and motion in the global model. Using a FSD results in a decreased ice thickness and concentration through increased lateral melting. The new wave mixing formulation gives a large decrease in surface roughness resulting in a decreased mixed layer depth. The associated reductions in heat diffusion result in increased ice thickness in large parts of the Arctic. Inclusion of the wave-dependent floe size distribution permits a positive feedback mechanism as wave height increases that can accelerate ice decline. Stronger wave activity will give larger surface roughness and hence stronger vertical mixing that may decrease future sea ice volumes.
SEA ICE, WAVES, Polar Regions, MODELLING
University of Southampton
Rynders, Stefanie
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Rynders, Stefanie
200bbfb5-1100-4ef3-a0e8-5b551e697a5d
Aksenov, Yevgeny
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Nurser, A.J. George
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Feltham, Daniel L.
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Naveira Garabato, Alberto
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Rynders, Stefanie (2017) Impact of surface waves on sea ice and ocean in the polar regions. University of Southampton, Doctoral Thesis, 205pp.

Record type: Thesis (Doctoral)

Abstract

Wave height in the Arctic is increasing and this is expected to continue as summer sea ice cover declines. The summer Marginal Ice Zone (MIZ), an area consisting of severely fragmented sea ice undergoing frequent collisions, is also expanding in the Arctic. Current climate and forecasting models are not adapted to simulate these conditions, yet accurate models are required because of climate change and the increasing human activity in the region. This project aims to improve such models by including wave-related processes that are currently lacking. A main focus is on sea ice rheology. A combined Collisional and Elastic-Viscous-Plastic (EVP) rheology is implemented in an idealised model configuration and in a global sea ice-ocean general circulation model. The combined rheology reflects both the granular behaviour of sea ice in the MIZ and the EVP rheology appropriate for pack ice conditions. This replaces the standard EVP rheology currently used in models. The effect of sea ice floe size, determined by wave break-up and thermodynamics, is also examined using a new floe size distribution (FSD) formulation. Finally, an existing wave mixing formulation is modied to use consistent wave information from the model rather than parameterisations. The combined rheology is found to be capable of maintaining a MIZ at high resolution in idealised simulations due to internal sea ice mechanisms only, while EVP is not. It also aaffects sea ice distribution and motion in the global model. Using a FSD results in a decreased ice thickness and concentration through increased lateral melting. The new wave mixing formulation gives a large decrease in surface roughness resulting in a decreased mixed layer depth. The associated reductions in heat diffusion result in increased ice thickness in large parts of the Arctic. Inclusion of the wave-dependent floe size distribution permits a positive feedback mechanism as wave height increases that can accelerate ice decline. Stronger wave activity will give larger surface roughness and hence stronger vertical mixing that may decrease future sea ice volumes.

Text
thesis - Version of Record
Restricted to Repository staff only until 15 February 2022.
Available under License University of Southampton Thesis Licence.

More information

Published date: July 2017
Keywords: SEA ICE, WAVES, Polar Regions, MODELLING

Identifiers

Local EPrints ID: 428655
URI: http://eprints.soton.ac.uk/id/eprint/428655
PURE UUID: 34e87707-8516-40fa-8b4d-3b82c6929f21
ORCID for Stefanie Rynders: ORCID iD orcid.org/0000-0003-1334-4577

Catalogue record

Date deposited: 05 Mar 2019 17:30
Last modified: 03 May 2019 00:26

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