Ocean Sci. Discuss., 7, 1439-1467, 2010
www.ocean-sci-discuss.net/7/1439/2010/
doi:10.5194/osd-7-1439-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Ocean Science (OS). Please refer to the corresponding final paper in OS.
Flow and mixing around a glacier tongue
C. L. Stevens1, C. L. Stewart1, N. J. Robinson1,2, M. J. M. Williams1, and T. G. Haskell3
1National Institute for Water and Atmospheric Research (NIWA), Greta Point Wellington, New Zealand
2Department of Marine Science, University of Otago, Dunedin, New Zealand
3Industrial Research Ltd. (IRL), Gracefield Lower Hutt, New Zealand

Abstract. A glacier tongue floating in the coastal ocean presents a significant obstacle to the local flow and influences oceanic mixing and transport processes. Here ocean shear microstructure observations at a glacier tongue side-wall show tidally-induced flow pulses and vortices as well as concomitant mixing. Flow speeds within the pulses reached around three times that of the ambient tidal flow amplitude and generated vertical velocity shear as large as 3×10−3 s−1. During the maximum flow period turbulent energy dissipation rates reached a maximum of 10−5 m2 s−3, around three decades greater than local background levels. This is in keeping with estimates of the gradient Richardson Number which dropped to around unity. Associated vertical diffusivities are higher that expected from parameterization, possibly reflecting the proximity of the cryotopography.

Citation: Stevens, C. L., Stewart, C. L., Robinson, N. J., Williams, M. J. M., and Haskell, T. G.: Flow and mixing around a glacier tongue, Ocean Sci. Discuss., 7, 1439-1467, doi:10.5194/osd-7-1439-2010, 2010.
 
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