Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica
The first turbulence profiler observations beneath land fast sea ice which is directly adjacent to an Antarctic ice shelf are described. The stratification in the 325 m deep water column consisted of a layer of supercooled water in the upper 40 m lying above a quasi-linearly stratified water column...
Main Authors: | , , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2009
|
Subjects: | |
Online Access: | https://doaj.org/article/053f9704670e4551aeddafc35900fd6a |
id |
ftdoajarticles:oai:doaj.org/article:053f9704670e4551aeddafc35900fd6a |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:053f9704670e4551aeddafc35900fd6a 2023-05-15T13:57:10+02:00 Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica C. L. Stevens N. J. Robinson M. J. M. Williams T. G. Haskell 2009-10-01T00:00:00Z https://doaj.org/article/053f9704670e4551aeddafc35900fd6a EN eng Copernicus Publications http://www.ocean-sci.net/5/435/2009/os-5-435-2009.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/053f9704670e4551aeddafc35900fd6a Ocean Science, Vol 5, Iss 4, Pp 435-445 (2009) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2009 ftdoajarticles 2022-12-31T08:50:57Z The first turbulence profiler observations beneath land fast sea ice which is directly adjacent to an Antarctic ice shelf are described. The stratification in the 325 m deep water column consisted of a layer of supercooled water in the upper 40 m lying above a quasi-linearly stratified water column with a sharp step in density at mid-depth. Turbulent energy dissipation rates were on average 3×10 −8 m 2 s −3 with peak bin-averaged values reaching 4×10 −7 m 2 s −3 . The local dissipation rate per unit area was estimated to be 10 m Wm −2 on average with a peak of 50 m Wm −2 . These values are consistent with a moderate baroclinic response to the tides. The small-scale turbulent energetics lie on the boundary between isotropy and buoyancy-affected. This will likely influence the formation and aggregation of frazil ice crystals within the supercooled layer. The data suggest that the large crystals observed in McMurdo Sound will transition from initial growth at scales smaller than the Kolmogorov lengthscale to sizes substantially (1–2 orders of magnitude) greater than the Kolmogorov scale. An estimate of the experiment-averaged vertical diffusivity of mass K ρ yields a coefficient of around 2×10 −4 m 2 s −1 although this increased by a factor of 2 near the surface. Combining this estimate of K ρ with available observations of average and maximum currents suggests the layer of supercooled water can persist for a distance of ~250 km from the front of the McMurdo Ice Shelf. Article in Journal/Newspaper Antarc* Antarctic Antarctica Ice Shelf McMurdo Ice Shelf McMurdo Sound Sea ice Directory of Open Access Journals: DOAJ Articles Antarctic McMurdo Sound McMurdo Ice Shelf ENVELOPE(166.500,166.500,-78.000,-78.000) |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 C. L. Stevens N. J. Robinson M. J. M. Williams T. G. Haskell Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
The first turbulence profiler observations beneath land fast sea ice which is directly adjacent to an Antarctic ice shelf are described. The stratification in the 325 m deep water column consisted of a layer of supercooled water in the upper 40 m lying above a quasi-linearly stratified water column with a sharp step in density at mid-depth. Turbulent energy dissipation rates were on average 3×10 −8 m 2 s −3 with peak bin-averaged values reaching 4×10 −7 m 2 s −3 . The local dissipation rate per unit area was estimated to be 10 m Wm −2 on average with a peak of 50 m Wm −2 . These values are consistent with a moderate baroclinic response to the tides. The small-scale turbulent energetics lie on the boundary between isotropy and buoyancy-affected. This will likely influence the formation and aggregation of frazil ice crystals within the supercooled layer. The data suggest that the large crystals observed in McMurdo Sound will transition from initial growth at scales smaller than the Kolmogorov lengthscale to sizes substantially (1–2 orders of magnitude) greater than the Kolmogorov scale. An estimate of the experiment-averaged vertical diffusivity of mass K ρ yields a coefficient of around 2×10 −4 m 2 s −1 although this increased by a factor of 2 near the surface. Combining this estimate of K ρ with available observations of average and maximum currents suggests the layer of supercooled water can persist for a distance of ~250 km from the front of the McMurdo Ice Shelf. |
format |
Article in Journal/Newspaper |
author |
C. L. Stevens N. J. Robinson M. J. M. Williams T. G. Haskell |
author_facet |
C. L. Stevens N. J. Robinson M. J. M. Williams T. G. Haskell |
author_sort |
C. L. Stevens |
title |
Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica |
title_short |
Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica |
title_full |
Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica |
title_fullStr |
Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica |
title_full_unstemmed |
Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica |
title_sort |
observations of turbulence beneath sea ice in southern mcmurdo sound, antarctica |
publisher |
Copernicus Publications |
publishDate |
2009 |
url |
https://doaj.org/article/053f9704670e4551aeddafc35900fd6a |
long_lat |
ENVELOPE(166.500,166.500,-78.000,-78.000) |
geographic |
Antarctic McMurdo Sound McMurdo Ice Shelf |
geographic_facet |
Antarctic McMurdo Sound McMurdo Ice Shelf |
genre |
Antarc* Antarctic Antarctica Ice Shelf McMurdo Ice Shelf McMurdo Sound Sea ice |
genre_facet |
Antarc* Antarctic Antarctica Ice Shelf McMurdo Ice Shelf McMurdo Sound Sea ice |
op_source |
Ocean Science, Vol 5, Iss 4, Pp 435-445 (2009) |
op_relation |
http://www.ocean-sci.net/5/435/2009/os-5-435-2009.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/053f9704670e4551aeddafc35900fd6a |
_version_ |
1766264770253553664 |