Flow and mixing near a glacier tongue: a pilot study

• Published in: Ocean Science
• Main Authors: Stevens, CL, Stewart, CL, Robinson, NJ, Williams, MJM, Haskell, TG
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Gesellchaft MHB; The Authors 2011
• Subjects: Science & Technology; Physical Sciences; Meteorology & Atmospheric Sciences; Oceanography; MCMURDO-SOUND; SEA-ICE; PLATELET ICE; ANTARCTICA; PARAMETERIZATION; MICROSTRUCTURE; DISSIPATION; NUMBER; FLUXES; McMurdo Sound; Antarc*; Antarctica; Sea ice
• Online Access: http://hdl.handle.net/2292/19138; https://doi.org/10.5194/os-7-293-2011

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) m(2) s(-3), around three decades greater than local background levels. This is in keeping with estimates of the gradient Richardson Number which dropped to similar 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.