Mixing Regimes in the Amundsen Basin of the Arctic Ocean
Thesis (Ph.D.)--University of Washington, 2016-06 We investigate the role of background mixing in the Arctic Ocean and how it has changed with changing forcing and ice cover. We have examined shear measurements made over more than 30 years to determine the variation in internal wave energy and mixin...
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ftunivwashington:oai:digital.lib.washington.edu:1773/36797 2023-05-15T13:22:42+02:00 Mixing Regimes in the Amundsen Basin of the Arctic Ocean Guthrie, John D. Morison, James 2016-06 application/pdf http://hdl.handle.net/1773/36797 en_US eng Guthrie_washington_0250E_16061.pdf http://hdl.handle.net/1773/36797 Double Diffusion Internal Waves Mixing Turbulence Physical oceanography oceanography Thesis 2016 ftunivwashington 2023-03-12T18:56:16Z Thesis (Ph.D.)--University of Washington, 2016-06 We investigate the role of background mixing in the Arctic Ocean and how it has changed with changing forcing and ice cover. We have examined shear measurements made over more than 30 years to determine the variation in internal wave energy and mixing in different regions of the Arctic Ocean. To improve estimates of thermal diffusivity and heat fluxes in the deep basins of the Arctic Ocean from the base of the mixed layer down to the Atlantic Water layer, we have presented results from three different data sets collected in the central Arctic Ocean as well as leveraging earlier microstructure observations. Using expendable current profilers in addition to moorings in the Canada Basin, we use shear variance to estimate diapycnal diffusivity in the central Arctic Ocean. We find little change in time despite drastic changes in sea ice extent during the same time period. However, some spatial variability is present with stronger mixing at depth in the Eurasian Basin and weaker mixing at depth in the Canada Basin. This is attributed to stronger under-ice dissipation in the Canada Basin removing energy from the internal wave field due to the stronger near-surface stratification resulting in that region. Using temperature microstructure profiles, the regimes of turbulent mixing and double diffusion in the Amundsen Basin during spring have been explored, with double diffusion dominating in 2013 and weak turbulence dominating in 2014. We have provided an updated version of a well-known heat flux parameterization for double diffusion that agrees to within 10% of the observed values. We have also shown that a convecting scaling exponent necessary in relating the Nusselt number and the Rayleigh number needs downward revision. In the absence of a thermohaline staircase, we calculate turbulent diffusivity. Heat fluxes for each mixing regime have been compared and contrasted, and we have proposed an upper bound on the level of turbulent diffusivity necessary to prevent ... Thesis amundsen basin Arctic Arctic Ocean canada basin Central Arctic Sea ice University of Washington, Seattle: ResearchWorks Amundsen Basin ENVELOPE(74.000,74.000,87.000,87.000) Arctic Arctic Ocean Canada |
institution |
Open Polar |
collection |
University of Washington, Seattle: ResearchWorks |
op_collection_id |
ftunivwashington |
language |
English |
topic |
Double Diffusion Internal Waves Mixing Turbulence Physical oceanography oceanography |
spellingShingle |
Double Diffusion Internal Waves Mixing Turbulence Physical oceanography oceanography Guthrie, John D. Mixing Regimes in the Amundsen Basin of the Arctic Ocean |
topic_facet |
Double Diffusion Internal Waves Mixing Turbulence Physical oceanography oceanography |
description |
Thesis (Ph.D.)--University of Washington, 2016-06 We investigate the role of background mixing in the Arctic Ocean and how it has changed with changing forcing and ice cover. We have examined shear measurements made over more than 30 years to determine the variation in internal wave energy and mixing in different regions of the Arctic Ocean. To improve estimates of thermal diffusivity and heat fluxes in the deep basins of the Arctic Ocean from the base of the mixed layer down to the Atlantic Water layer, we have presented results from three different data sets collected in the central Arctic Ocean as well as leveraging earlier microstructure observations. Using expendable current profilers in addition to moorings in the Canada Basin, we use shear variance to estimate diapycnal diffusivity in the central Arctic Ocean. We find little change in time despite drastic changes in sea ice extent during the same time period. However, some spatial variability is present with stronger mixing at depth in the Eurasian Basin and weaker mixing at depth in the Canada Basin. This is attributed to stronger under-ice dissipation in the Canada Basin removing energy from the internal wave field due to the stronger near-surface stratification resulting in that region. Using temperature microstructure profiles, the regimes of turbulent mixing and double diffusion in the Amundsen Basin during spring have been explored, with double diffusion dominating in 2013 and weak turbulence dominating in 2014. We have provided an updated version of a well-known heat flux parameterization for double diffusion that agrees to within 10% of the observed values. We have also shown that a convecting scaling exponent necessary in relating the Nusselt number and the Rayleigh number needs downward revision. In the absence of a thermohaline staircase, we calculate turbulent diffusivity. Heat fluxes for each mixing regime have been compared and contrasted, and we have proposed an upper bound on the level of turbulent diffusivity necessary to prevent ... |
author2 |
Morison, James |
format |
Thesis |
author |
Guthrie, John D. |
author_facet |
Guthrie, John D. |
author_sort |
Guthrie, John D. |
title |
Mixing Regimes in the Amundsen Basin of the Arctic Ocean |
title_short |
Mixing Regimes in the Amundsen Basin of the Arctic Ocean |
title_full |
Mixing Regimes in the Amundsen Basin of the Arctic Ocean |
title_fullStr |
Mixing Regimes in the Amundsen Basin of the Arctic Ocean |
title_full_unstemmed |
Mixing Regimes in the Amundsen Basin of the Arctic Ocean |
title_sort |
mixing regimes in the amundsen basin of the arctic ocean |
publishDate |
2016 |
url |
http://hdl.handle.net/1773/36797 |
long_lat |
ENVELOPE(74.000,74.000,87.000,87.000) |
geographic |
Amundsen Basin Arctic Arctic Ocean Canada |
geographic_facet |
Amundsen Basin Arctic Arctic Ocean Canada |
genre |
amundsen basin Arctic Arctic Ocean canada basin Central Arctic Sea ice |
genre_facet |
amundsen basin Arctic Arctic Ocean canada basin Central Arctic Sea ice |
op_relation |
Guthrie_washington_0250E_16061.pdf http://hdl.handle.net/1773/36797 |
_version_ |
1766366413312753664 |