Are seasonal calving dynamics forced by buttressing from ice mélange or undercutting by melting? Outcomes from full-Stokes simulations of Store Gletscher, West Greenland

We use a full-Stokes 2-D model (Elmer/Ice) to investigate the flow and calving dynamics of Store Gletscher, a fast flowing outlet glacier in West Greenland. Based on a new, subgrid-scale implementation of the crevasse depth calving criterion, we perform two sets of simulations; one to identify the primary forcing mechanisms and another to constrain future stability. We find that the mixture of icebergs and sea-ice, known as ice mélange or sikussak, is principally responsible for the observed seasonal advance of the ice front, whereas submarine melting plays a secondary role. Sensitivity analysis demonstrates that the glacier's calving dynamics are sensitive to seasonal perturbation, but are stable on interannual timescales due to the glacier's topographic setting. Our results shed light on the dynamics of calving glaciers while explaining why neighbouring glaciers do not necessarily respond synchronously to changes in atmospheric and oceanic forcing.This study was funded by the Natural Environment Research Council through a Ph.D. studentship (grant no. NE/K500884/1) to J. Todd and research grant (NE/K005871/1) to P. ChristoffersenThis is the final version, which can also be found on the journal's website at: http://www.the-cryosphere-discuss.net/8/3525/2014/tcd-8-3525-2014.htm