Boundary layer models for calving marine outlet glaciers
Christian Schoof1, Andrew D. Davis2, and Tiberiu V. Popa11Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2207 Main Mall, Vancouver, BC, V6T 1Z4, Canada 2Department of Aeronautical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
Received: 17 Mar 2017 – Accepted for review: 27 Mar 2017 – Discussion started: 28 Mar 2017
Abstract. We consider the flow of marine-terminating outlet glaciers that are laterally confined in a channel of prescribed width. In that case, the drag exerted by the channel side walls on the glacier affects extensional stress at the grounding line, and as a result, the flux through the grounding line. Lateral drag in turn is affected by the length of the floating ice shelf when the latter is present, and therefore by calving. Using two calving laws, one due to Nick et al based on a model for crevasse propagation due to hydrofracture, and the other simply asserting that calving occurs where the glacier ice becomes afloat, we pose and analyse a flowline model by two methods: direct numerical solution and matched asymptotic expansions. The latter leads to a boundary layer formulation that predicts flux through the grounding line as a function of depth to bedrock, channel width, basal drag coefficient, and a calving parameter. By contrast with unbuttressed marine ice sheets, we find that flux can decrease with increasing depth to bedrock at the grounding line, reversing the usual stability criterion for steady grounding line location. We show how this anomalous behaviour relates to the strength of lateral versus basal drag on the grounded portion of the glacier, and to the specifics of the calving law used.
Schoof, C., Davis, A. D., and Popa, T. V.: Boundary layer models for calving marine outlet glaciers, The Cryosphere Discuss., doi:10.5194/tc-2017-42, in review, 2017.