Distribution of subglacial channels beneath the Greenland Ice Sheet based on airborne radar sounding

Outlet glaciers in the Greenland Ice Sheet are known to display variable sensitivity to meltwater input. On the southwest coast, surface meltwater input causes some glaciers to accelerate, while on the eastern coast, additional meltwater slows down ice flow. Part of this regional variability could be associated with the degree of subglacial channelization and how far efficient channels extend inland beneath individual glaciers. However, currently, there are no observations on the spatial distribution of subglacial channels beneath the Greenland Ice Sheet that could be used to test this hypothesis on a large scale. Previous studies in West Antarctica have demonstrated that the presence of distributed versus channelized flow can be inferred from airborne radar sounding observations using a combination of specularity content and bed reflectivity. To date, such techniques have been not applied to the two decades worth of airborne radar sounding data collected in Greenland by NASA Operation IceBridge and NSF CReSIS studies. This study will be the first attempt to perform specularity analysis using these data. The goal is to map the distribution of subglacial channels beneath Greenland in early spring using a combined specularity and bed reflectivity approach. We first use previously published results from Thwaites Glacier to calibrate the specularity methodology for OIB/CReSIS data. We then present new results on the distribution of subglacial drainage morphology for selected glaciers in Greenland.