Small-scale dynamics of the under-ice boundary layer
In ice covered polar regions, the interaction between ocean, ice and atmosphere is an important component in the complex climate system. Exchange of heat, mass and momentum occurs across the boundary layers, both in the ocean and in the atmosphere, hence understanding the involved processes are cruc...
Published in: | Geophysical Research Letters |
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Language: | English |
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The University of Bergen
2009
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ftunivbergen:oai:bora.uib.no:1956/3450 2023-05-15T18:18:56+02:00 Small-scale dynamics of the under-ice boundary layer Sirevaag, Anders 2009-01-09 application/pdf https://hdl.handle.net/1956/3450 eng eng The University of Bergen Paper I: Geophysical Research Letters 36, Sirevaag, A., Turbulent exchange coefficients for the ice/ocean interface in case of rapid melting, L04606. Copyright 2009 The American Geophysical Union. Reproduced with permission. Submitted version. The published version is available at: http://dx.doi.org/10.1029/2008GL036587 Paper II: Journal of Physical Oceanography 39(12), Sirevaag, A.; Fer, I., Early spring oceanic heat fluxes and mixing observed from drift stations north of Svalbard, pp. 3049–3069. Copyright 2009 American Meteorological Society. Full text not available in BORA due to publisher restrictions. The published version is available at: http://dx.doi.org/10.1175/2009JPO4172.1 Paper III: Sirevaag, A.; McPhee, M. G.; Morison, J. H.; Shaw, W. J.; Stanton, T. P., 2009, Wintertime mixed layer measurements at Maud Rise, Weddell Sea. Reproduced with permission. Submitted version. Paper IV: Geophysical Research Letters 31, Fer, I.; McPhee, M. G.; Sirevaag, A., Conditional statistics of the Reynolds stress in the under-ice boundary layer, L15311. Copyright 2004 The American Geophysical Union. Reproduced with permission. Accepted version. The published version is available at: http://dx.doi.org/10.1029/2004GL020475 urn:isbn:978-82-308-0720-0 (print version) https://hdl.handle.net/1956/3450 Anders Sirevaag VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 Doctoral thesis 2009 ftunivbergen https://doi.org/10.1029/2008GL03658710.1175/2009JPO4172.110.1029/2004GL020475 2023-03-14T17:41:50Z In ice covered polar regions, the interaction between ocean, ice and atmosphere is an important component in the complex climate system. Exchange of heat, mass and momentum occurs across the boundary layers, both in the ocean and in the atmosphere, hence understanding the involved processes are crucial in order to determine future climate. In this thesis dynamics and thermodynamics of the under-ice boundary layer are investigated based on measurements of turbulent fluxes in close proximity to the ice/ocean interface and microstructure profiling of the upper ocean. The topic is addressed in four papers which focus on exchange processes at the ice/ocean interface as well as regional measurements of turbulence and turbulent fluxes in ice covered areas around Spitsbergen and in the Weddell Sea. High rates of melting are often encountered as sea ice drifts into water with temperatures well above freezing, which may be typical of the marginal ice zones. It has been shown in previous studies that these melting rates are limited by double diffusive effects in a thin layer close the ice/ocean interface. In this study, turbulent fluxes from the under-ice boundary layer are used to show that double diffusive effects are important for the melting rates and show that the strength of this double diffusion is close to the range suggested by previous studies. It is also shown that by not considering double diffusive effects at the boundary, melting rates are overestimated by up to several cm per day. By analyzing the conditional statistics of the Reynolds stress in the boundary layer it is found that the main fraction of the stress comes from high turbulence events, so called “sweeps” and “ejections”, which is consistent with boundary layer flows in other environments. Closest to the ice, the sweeps are found to be more intense than further away from the interface, which can be related to the observed increase in friction velocity with depth. The West Spitsbergen Current transports Atlantic Water, which is the main source of ... Doctoral or Postdoctoral Thesis Sea ice Weddell Sea ice covered areas Spitsbergen University of Bergen: Bergen Open Research Archive (BORA-UiB) Weddell Weddell Sea Geophysical Research Letters 36 4 |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
topic |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 |
spellingShingle |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 Sirevaag, Anders Small-scale dynamics of the under-ice boundary layer |
topic_facet |
VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 |
description |
In ice covered polar regions, the interaction between ocean, ice and atmosphere is an important component in the complex climate system. Exchange of heat, mass and momentum occurs across the boundary layers, both in the ocean and in the atmosphere, hence understanding the involved processes are crucial in order to determine future climate. In this thesis dynamics and thermodynamics of the under-ice boundary layer are investigated based on measurements of turbulent fluxes in close proximity to the ice/ocean interface and microstructure profiling of the upper ocean. The topic is addressed in four papers which focus on exchange processes at the ice/ocean interface as well as regional measurements of turbulence and turbulent fluxes in ice covered areas around Spitsbergen and in the Weddell Sea. High rates of melting are often encountered as sea ice drifts into water with temperatures well above freezing, which may be typical of the marginal ice zones. It has been shown in previous studies that these melting rates are limited by double diffusive effects in a thin layer close the ice/ocean interface. In this study, turbulent fluxes from the under-ice boundary layer are used to show that double diffusive effects are important for the melting rates and show that the strength of this double diffusion is close to the range suggested by previous studies. It is also shown that by not considering double diffusive effects at the boundary, melting rates are overestimated by up to several cm per day. By analyzing the conditional statistics of the Reynolds stress in the boundary layer it is found that the main fraction of the stress comes from high turbulence events, so called “sweeps” and “ejections”, which is consistent with boundary layer flows in other environments. Closest to the ice, the sweeps are found to be more intense than further away from the interface, which can be related to the observed increase in friction velocity with depth. The West Spitsbergen Current transports Atlantic Water, which is the main source of ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Sirevaag, Anders |
author_facet |
Sirevaag, Anders |
author_sort |
Sirevaag, Anders |
title |
Small-scale dynamics of the under-ice boundary layer |
title_short |
Small-scale dynamics of the under-ice boundary layer |
title_full |
Small-scale dynamics of the under-ice boundary layer |
title_fullStr |
Small-scale dynamics of the under-ice boundary layer |
title_full_unstemmed |
Small-scale dynamics of the under-ice boundary layer |
title_sort |
small-scale dynamics of the under-ice boundary layer |
publisher |
The University of Bergen |
publishDate |
2009 |
url |
https://hdl.handle.net/1956/3450 |
geographic |
Weddell Weddell Sea |
geographic_facet |
Weddell Weddell Sea |
genre |
Sea ice Weddell Sea ice covered areas Spitsbergen |
genre_facet |
Sea ice Weddell Sea ice covered areas Spitsbergen |
op_relation |
Paper I: Geophysical Research Letters 36, Sirevaag, A., Turbulent exchange coefficients for the ice/ocean interface in case of rapid melting, L04606. Copyright 2009 The American Geophysical Union. Reproduced with permission. Submitted version. The published version is available at: http://dx.doi.org/10.1029/2008GL036587 Paper II: Journal of Physical Oceanography 39(12), Sirevaag, A.; Fer, I., Early spring oceanic heat fluxes and mixing observed from drift stations north of Svalbard, pp. 3049–3069. Copyright 2009 American Meteorological Society. Full text not available in BORA due to publisher restrictions. The published version is available at: http://dx.doi.org/10.1175/2009JPO4172.1 Paper III: Sirevaag, A.; McPhee, M. G.; Morison, J. H.; Shaw, W. J.; Stanton, T. P., 2009, Wintertime mixed layer measurements at Maud Rise, Weddell Sea. Reproduced with permission. Submitted version. Paper IV: Geophysical Research Letters 31, Fer, I.; McPhee, M. G.; Sirevaag, A., Conditional statistics of the Reynolds stress in the under-ice boundary layer, L15311. Copyright 2004 The American Geophysical Union. Reproduced with permission. Accepted version. The published version is available at: http://dx.doi.org/10.1029/2004GL020475 urn:isbn:978-82-308-0720-0 (print version) https://hdl.handle.net/1956/3450 |
op_rights |
Anders Sirevaag |
op_doi |
https://doi.org/10.1029/2008GL03658710.1175/2009JPO4172.110.1029/2004GL020475 |
container_title |
Geophysical Research Letters |
container_volume |
36 |
container_issue |
4 |
_version_ |
1766195704476205056 |