Parameterising crevasse field drainage into meltwater routing models for the Greenland Ice Sheet

Nearly all meltwater produced on the Greenland Ice Sheet surface is routed through the interior of the ice, and the spatial and temporal patterns – as well as the mode of delivery – of discharge to the bed can have significant consequences for processes including ice fracture, rheology, and basal sliding. Existing suggest that a majority of meltwater in Greenland is transferred to the bed via surface crevasse fields, rather than lakes or moulins. However, in contrast to well-observed phenomena such as supraglacial lake drainages, little work has been done to explore how this process should be parameterised in regional-scale models that route meltwater from the surface to the bed. Here, we explore: (i) how well observations of crevasse field filling and drainage support existing parameterisations based upon linear elastic fracture mechanics (LEFM); (ii) what modifications may need to be implemented to better represent crevasse field hydrology, including the choice of proxy for resistive stress (R_xx) and the inclusion of seasonally-varying stress; and (iii) the potential consequences for effective and sliding at the glacier bed, as represented through subglacial hydrological models.