Intercomparison of surface meltwater routing models for the Greenland ice sheet and influence on subglacial effective pressures

Supraglacial surface routing delays may propagate to englacial and subglacial hydrologic systems, requiring accurate assessment to correctly estimate subglacial effective pressures. We compare hourly supraglacial moulin discharge simulations from three surface meltwater routing models - the synthetic unit hydrograph (SUH), the bareice component of surface routing and lake filling (SRLF), and the rescaled width function (RWF) - for four internally drained catchments on the southwestern Greenland ice sheet surface.

The routing models are forced identically using surface runoff from the Modele Atmospherique Regionale regional climate model (RCM). For each catchment, simulated moulin hydrographs are input to the SHAKTI subglacial hydrologic model to simulate diurnally varying subglacial effective-pressure variations in the vicinity of a single moulin. Overall, all three routing models produce more realistic moulin discharges than simply using RCM runoff outputs without surface routing but produce significant differences in peak moulin discharge and time to peak.