Challenges in predicting Greenland supraglacial lake drainages at the regional scale

Abstract. A leading hypothesis for the mechanism of fast supraglacial lake drainages is that transient extensional stresses briefly allow crevassing in otherwise compressional ice flow regimes. Lake water can then hydrofracture a crevasse to base sheet, and river inputs maintain this connection as moulin. If future sheet models are accurately represent moulins, we must understand their formation processes, timescales, locations. Here, use remote-sensing velocity products constrain relationship between strain rates across ∼ 1600 km2 Pâkitsoq, western Greenland, 2002–2019. We find significantly more background at moulins associated with fast-draining lakes than slow-draining or non-draining moulins. test whether settings drain earlier, but insignificant correlation. To investigate frequency which strain-rate transients drainage, examined Landsat-derived over 16 32 d periods 240 fast-lake-drainage events 18 years. low signal-to-noise ratio, presence water, multi-week repeat cycle obscured any resolution hypothesized rates. Our results support drive drainages. However, current generation products, even when stacked hundreds drainages, cannot resolve these transients. Thus, observational progress understanding drainage initiation will rely on field-based tools such GPS networks photogrammetry.