Articles | Volume 7, issue 3
https://doi.org/10.5194/os-7-293-2011
https://doi.org/10.5194/os-7-293-2011
Research article
 | 
06 May 2011
Research article |  | 06 May 2011

Flow and mixing near a glacier tongue: a pilot study

C. L. Stevens, C. L. Stewart, N. J. Robinson, M. J. M. Williams, and T. G. Haskell

Abstract. A glacier tongue floating in the coastal ocean presents a significant obstacle to the local flow and so influences oceanic mixing and transport processes. Here acoustic Doppler current profiler and shear microstructure observations very near to a glacier tongue side-wall capture flow accelerations and associated mixing. Flow speeds reached around 40 cm s−1, twice that of the ambient tidal flow amplitude, and generated vertical velocity shear squared as large as 10−5 s−2. During the time of maximum flow, turbulent energy dissipation rates reached 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 ~1 during maximum flow. Associated vertical diffusivities estimated from the shear microstructure results were substantial, reflecting the influence of the glacier on velocity gradients.

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