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| Titel |
Observations of turbulence beneath sea ice in southern McMurdo Sound, Antarctica |
| VerfasserIn |
C. L. Stevens, N. J. Robinson, M. J. M. Williams, T. G. Haskell |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 5, no. 4 ; Nr. 5, no. 4 (2009-10-26), S.435-445 |
| Datensatznummer |
250002722
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| Publikation (Nr.) |
 copernicus.org/os-5-435-2009.pdf |
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| Zusammenfassung |
| 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 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 Kρ yields a coefficient of around
2×10−4 m2s−1 although this increased by a factor of 2 near
the surface. 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 ~250 km from the front
of the McMurdo Ice Shelf. |
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