Ocean Dynamics

, Volume 65, Issue 11, pp 1535–1546

Modelling subglacial discharge and its influence on ocean heat transport in Arctic fjords

  • Jørgen Bendtsen
  • John Mortensen
  • Søren Rysgaard
Article
Part of the following topical collections:
  1. Topical Collection on the 17th biennial workshop of the Joint Numerical Sea Modelling Group (JONSMOD) in Brussels, Belgium 12-14 May 2014

Abstract

Tidewater outlet glaciers are directly connected to the ocean via ice walls or floating shelves. Melting and freezing of ice, runoff, englacial, and subglacial discharge of freshwater and ocean heat transport are therefore potential feedback processes between glacial ice flow and ocean circulation. Subglacial discharge occurs at the base of tidewater glacier outlets where out-flowing freshwater forms a convective buoyant plume ascending close to the glacier face and, due to entrainment, transports relatively warm and saline ambient bottom water up towards the surface. Plume dynamics, typically occurring at sub-grid scales in regional ocean models, therefore has to be parameterized in areas where ice-ocean interactions occur, as for example in Arctic fjords. Here, we develop and analyze a new simple boundary condition of subglacial discharge where entrainment-induced transport between the subsurface and surface layer is described. A sensitivity study showed that subglacial discharge increased ocean heat transport near the glacier whereas the impact from plume-entrainment became relatively small further from the glacier. Subglacial discharge was shown to have a significant influence on surface concentrations. The impact from subglacial discharge was demonstrated in a regional model of Godthåbsfjord (64°N), located at the west coast of Greenland, where surface concentrations near the glacier were shown to be sensitive to subglacial discharge in accordance with observations.

Keywords

Fjord circulation Subglacial freshwater discharge Heat transport Tidewater outlet glacier Ocean glacier interaction Buoyant plume convection 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Jørgen Bendtsen
    • 1
    • 2
  • John Mortensen
    • 3
  • Søren Rysgaard
    • 1
    • 3
    • 4
  1. 1.Arctic Research Centre, Aarhus UniversityAarhus CDenmark
  2. 2.ClimateLab, Symbion Science ParkCopenhagen ODenmark
  3. 3.Greenland Climate Research Centre, Greenland Institute of Natural ResourcesNuukGreenland
  4. 4.Center for Earth Observation Science, CHR Faculty of Environment, Earth, and Resources, University of ManitobaWinnipegCanada

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