Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2012 Interactions between the ocean circulation in sub-ice shelf cavities and the overlying ice shelf have rece...
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Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
2012
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/5543 2023-05-15T13:53:14+02:00 Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents Dansereau, Veronique Pine Island Ice Shelf, West Antarctica 2012-09 application/pdf https://hdl.handle.net/1912/5543 en_US eng Massachusetts Institute of Technology and Woods Hole Oceanographic Institution WHOI Theses https://hdl.handle.net/1912/5543 doi:10.1575/1912/5543 doi:10.1575/1912/5543 Ocean circulation Ocean currents Thesis 2012 ftwhoas https://doi.org/10.1575/1912/5543 2022-05-28T22:58:43Z Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2012 Interactions between the ocean circulation in sub-ice shelf cavities and the overlying ice shelf have received considerable attention in the context of observed changes in flow speeds of marine ice sheets around Antarctica. Modeling these interactions requires parameterizing the turbulent boundary layer processes to infer melt rates from the oceanic state at the ice-ocean interface. Here we explore two such parameterizations in the context of the MIT ocean general circulation model coupled to the z-coordinates ice shelf cavity model of Losch (2008). We investigate both idealized ice shelf cavity geometries as well as a realistic cavity under Pine Island Ice Shelf (PIIS), West Antarctica. Our starting point is a three-equation melt rate parameterization implemented by Losch (2008), which is based on the work of Hellmer and Olbers (1989). In this form, the transfer coefficients for calculating heat and freshwater fluxes are independent of frictional turbulence induced by the proximity of the moving ocean to the fixed ice interface. More recently, Holland and Jenkins (1999) have proposed a parameterization in which the transfer coefficients do depend on the ocean-induced turbulence and are directly coupled to the speed of currents in the ocean mixed layer underneath the ice shelf through a quadratic drag formulation and a bulk drag coefficient. The melt rate parameterization in the MITgcm is augmented to account for this velocity dependence. First, the effect of the augmented formulation is investigated in terms of its impact on melt rates as well as on its feedback on the wider sub-ice shelf circulation. We find that, over a wide range of drag coefficients, velocity-dependent melt rates are more strongly constrained by the distribution of mixed layer currents than by the temperature gradient between the shelf base and ... Thesis Antarc* Antarctica Ice Shelf Pine Island West Antarctica Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) West Antarctica Woods Hole, MA |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Ocean circulation Ocean currents |
spellingShingle |
Ocean circulation Ocean currents Dansereau, Veronique Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents |
topic_facet |
Ocean circulation Ocean currents |
description |
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2012 Interactions between the ocean circulation in sub-ice shelf cavities and the overlying ice shelf have received considerable attention in the context of observed changes in flow speeds of marine ice sheets around Antarctica. Modeling these interactions requires parameterizing the turbulent boundary layer processes to infer melt rates from the oceanic state at the ice-ocean interface. Here we explore two such parameterizations in the context of the MIT ocean general circulation model coupled to the z-coordinates ice shelf cavity model of Losch (2008). We investigate both idealized ice shelf cavity geometries as well as a realistic cavity under Pine Island Ice Shelf (PIIS), West Antarctica. Our starting point is a three-equation melt rate parameterization implemented by Losch (2008), which is based on the work of Hellmer and Olbers (1989). In this form, the transfer coefficients for calculating heat and freshwater fluxes are independent of frictional turbulence induced by the proximity of the moving ocean to the fixed ice interface. More recently, Holland and Jenkins (1999) have proposed a parameterization in which the transfer coefficients do depend on the ocean-induced turbulence and are directly coupled to the speed of currents in the ocean mixed layer underneath the ice shelf through a quadratic drag formulation and a bulk drag coefficient. The melt rate parameterization in the MITgcm is augmented to account for this velocity dependence. First, the effect of the augmented formulation is investigated in terms of its impact on melt rates as well as on its feedback on the wider sub-ice shelf circulation. We find that, over a wide range of drag coefficients, velocity-dependent melt rates are more strongly constrained by the distribution of mixed layer currents than by the temperature gradient between the shelf base and ... |
format |
Thesis |
author |
Dansereau, Veronique |
author_facet |
Dansereau, Veronique |
author_sort |
Dansereau, Veronique |
title |
Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents |
title_short |
Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents |
title_full |
Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents |
title_fullStr |
Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents |
title_full_unstemmed |
Ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents |
title_sort |
ice shelf-ocean interactions in a general circulation model : melt-rate modulation due to mean flow and tidal currents |
publisher |
Massachusetts Institute of Technology and Woods Hole Oceanographic Institution |
publishDate |
2012 |
url |
https://hdl.handle.net/1912/5543 |
op_coverage |
Pine Island Ice Shelf, West Antarctica |
geographic |
West Antarctica |
geographic_facet |
West Antarctica |
genre |
Antarc* Antarctica Ice Shelf Pine Island West Antarctica |
genre_facet |
Antarc* Antarctica Ice Shelf Pine Island West Antarctica |
op_source |
doi:10.1575/1912/5543 |
op_relation |
WHOI Theses https://hdl.handle.net/1912/5543 doi:10.1575/1912/5543 |
op_doi |
https://doi.org/10.1575/1912/5543 |
op_publisher_place |
Woods Hole, MA |
_version_ |
1766258242013364224 |