Subglacial hydrology modelling: achievements and challenges in simulating entire ice sheets
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As ice sheet dynamics is gravity-driven, lubricated flow, the subglacial hydrological environment has a strong impact on the seasonality of glaciers, but also plays a major role in ice stream genesis and shutdown. The system comprises several elements, from thin water films to channels, which are very different in their efficiency at transporting water. We use an equivalent-porous-medium approach that represents confined and unconfined aquifers. The code CUAS-MPI [1] is a performant model used to simulate subglacial systems of the Greenland and Antarctic ice sheets. We demonstrate that the simulated water discharge matches indirect observations like locations of plumes in fjords around Greenland, but also the challenges that massive water input during the rapid onset of the melt season poses to the modelling concept. The ultimate goal is to couple ice sheet and subglacial hydrology simulations. To this end, we use the coupling library preCICE [2] and present examples for an artificial geometry, as well as Greenland. Here, we are concerned with the initialisation, selection of coupling time steps, and report typical performance metrics. We conclude by discussing the challenges regarding throughput and the advantages of this type of modelling for constraining sliding at ice-sheet beds.
