Elmer/Ice News

Evolution of ice-shelf channels in Antarctic ice shelves

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Ice shelves buttress the continental ice flux and mediate ice–ocean interactions. They are often traversed by channels in which basal melting is enhanced, impacting ice-shelf stability. Here, channel evolution is investigated using Elmer/Ice and modeling results are qualitatively compared with geophysical data collected on the Roi Baudouin Ice Shelf (RBIS), Antarctica. The modeling confirms basal melting as a feasible mechanism for channel creation, although channels may also advect without melting for many tens of kilometers. Channels can be out of hydrostatic equilibrium depending on their width and the upstream melt history. Inverting surface elevation for ice thickness using hydrostatic equilibrium in those areas is erroneous, and corresponding observational evidence is presented at RBIS by comparing the hydrostatically inverted ice thickness with radar measurements. The model shows that channelized melting imprints the flow field characteristically, which can result in enhanced horizontal shearing across channels. This is exemplified for a channel at RBIS using observed surface velocities and opens up the possibility to classify channelized melting from space, an important step towards incorporating these effects in ice–ocean models.

Drews R., 2015. Evolution of ice-shelf channels in Antarctic ice shelves, The Cryosphere, 9, 1169-1181, doi:10.5194/tc-9-1169-2015.

 

Elmer/Ice at IGS Iceland Symposium

iceland2015A lot of presentations on a large variety of subjects using Elmer/Ice at the International Symposium on the Hydrology of Glaciers and Ice Sheets, held in Hofn, Iceland from 21th to 26 of June 2015. Among them, Doug MacAyeal using Elmer/Ice to model Viking sword. Have a look to the program here.

Impact of submarine frontal melting and ice mélange on glacier dynamics

krug15Submarine melting of the calving face of tidewater glaciers and the mechanical back force applied by the ice mélange layer are two mechanisms generally proposed to explain seasonal variations at the calving front of tidewater glaciers. However, the way these processes affect the calving rate and glacier dynamics remains uncertain. In this study, we used Elmer/ice to simulate the impact of these forcings on two-dimensional theoretical flow line glacier configurations. The model, which includes calving processes, suggests that frontal melting affects the position of the terminus only slightly (less than a few hundred metres) and does not affect the multiannual glacier mass balance at all. However, the ice mélange has a greater impact on the advance and retreat cycles of the glacier front (more than several kilometres) and its consequences for the mass balance are not completely negligible, stressing the need for better characterization of forcing properties. We also show that ice mélange forcing against the calving face can mechanically prevent crevasse propagation at sea level and hence prevent calving. Results also reveal different behaviours in grounded and floating glaciers: in the case of a floating extension, the strongest forcings can disrupt the glacier equilibrium by modifying its buttressing and ice flux at the grounding line.

 

Krug, J., G. Durand, O. Gagliardini and J. Weiss, 2015. Modelling the impact of submarine frontal melting and ice mélange on glacier dynamics, The Cryosphere, 9, 989-1003, doi:10.5194/tc-9-989-2015.

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