Flow and mixing near a glacier tongue: a pilot study

Abstract

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 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 ∼1 during maximum flow. Associated vertical diffusivities estimated from the shear microstructure results were substantial, reflecting the influence of the glacier on velocity gradients.

The influence of an Antarctic glacier tongue on near-field ocean circulation and mixing

“…Stevens et al . [] assumed a glacier thickness at the wall of around 50 m, based on velocity and stratification structure, as well as the tip thickness identified earlier. However, from the hydrostatic consideration of the freeboard transects, it would appear that the walls of the submerged glacier slopes away gradually so that the center of the glacier, not far back from the tip, is roughly twice this thickness, reaching a depth of 125 m in the middle of the glacier.…”

“…This enabled estimation of the turbulent energy dissipation rate ε (m 2 s −3 = W kg −1 ) using standard techniques [ Wolk et al ., ]. This type of device has been used in such conditions previously [ Stevens et al ., ; Fer et al ., ]. Profiles were recorded over a number of periods during the camp occupation.…”

“…The EGT divides the surface waters of Erebus Bay between the Dellbridge Islands and Cape Armitage (Figure ). The present work builds on a brief pilot study conducted in 2009 in the same location [ Stevens et al ., ]. Observations of flow speeds of 40 cm s −1 were made during this study and conditions suitable for shear‐generated turbulence were identified.…”

<i>Brief Communication</i> "The 2013 Erebus Glacier Tongue calving event"

“…Flow speeds in the region comprise 10 cm s −1 regional circulation and tidal speeds on top of this of as much as 15 cm s −1 (Stevens et al, 2011). The eastern side of the sound is generally thought to flow southward (Robinson and Williams, 2012).…”

Turbulent heat transfer as a control of platelet ice growth in supercooled under-ice ocean boundary layers

“…The general layout of EFC and its location relative to nearby geographic features is described by Stevens et al (2014Stevens et al ( , 2011 and shown in Fig. 2.…”