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www.ocean-sci-discuss.net/6/1407/2009/
doi:10.5194/osd-6-1407-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica
1National Institute for Water and Atmospheric Research (NIWA), Greta Point Wellington, New Zealand
2University of Otago, Dunedin, New Zealand
3Industrial Research Ltd (IRL), Gracefield, Lower Hutt, New Zealand
Abstract. 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 m2 s−3 with peak bin-averaged values reaching 4×10−7 m2 s−3. The local dissipation rate per unit area was estimated to be 10 mWm−2 on average with a peak of 50 mWm−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. An estimate of the vertical diffusivity of mass Kρ yields a coefficient of around 10−3 m2 s−1. Combining this estimate of Kρ with available observations of average and maximum currents suggests the layer of supercooled water can persist for a distance of ~20 km from the front of the McMurdo Ice Shelf.
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Citation: Stevens, C. L., Robinson, N. J., Williams, M. J. M., and Haskell, T. G.: Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica, Ocean Sci. Discuss., 6, 1407-1436, doi:10.5194/osd-6-1407-2009, 2009. Bibtex EndNote Reference Manager XML
