The impact of surface melt rate and catchment characteristics on Greenland Ice Sheet moulin inputs

Abstract

Abstract. The supraglacial drainage system of the Greenland Ice Sheet, in combination with surface melt rate, controls the rate of water flow into moulins, a major driver of subglacial water pressure. We apply the Subaerial Drainage System (SaDS) model, a physically based surface meltwater flow model, to a ∼20×27km2 catchment on the southwestern Greenland Ice Sheet for 4 years of melt forcing (2011, 2012, 2015, and 2016) to (1) examine the relationship between surface melt rate and the rate, diurnal amplitude, and timing of surface inputs to moulins; (2) compare SaDS to contemporary models; and (3) present a framework for selecting appropriate supraglacial drainage models for different modelling objectives. We find that variations in the rate and timing of modelled moulin inputs related to the development of supraglacial channels are relatively more important in years with low melt volumes than years with high melt volumes. We suggest that a process-resolving supraglacial hydrology model (e.g., SaDS) should be considered when modelling outcomes are sensitive to subdiurnal and long-term seasonal changes in the rate of discharge into moulins.