The Spatial Variability and Characteristics of Moulins in southwest Greenland

Moulins convey surface water to the bed of glaciers and ice sheets, where subglacial hydrological processes can influence ice velocity. Knowing where and how moulins form is therefore a critical component of predicting future ice sheet dynamics under enhanced ice melt conditions. This research explores the ways in which ice dynamics and surface hydrological processes collectively produce the spatial arrangements of moulins in a study area in south west Greenland. We adopt an empirical and spatial approach, and consider moulin location relative to ice velocity, surface strain rates, ice thickness, ice surface topography, meltwater discharge, lake location, and crevasse fields. We observe that moulin formation is most common in low velocity, high strain rate ice regimes with adverse bed slopes. Additionally, we observe that moulins proximal to in-situ drained lakes are predominantly located down-ice of the lake, and many of these moulins appear to have no obvious formative mechanism. In-situ drained lakes are located significantly closer to moulins than are non-draining lakes. We interpret these findings to support the theory that lake hydrofracture is a transient process related to temporary ice flexure in response to rapid moulin drainage events. We suggest that models could better incorporate processes of ice-conditioning into simulations of moulin formation.