Melting and mixing at the ocean-glacier interface

Around the globe, glaciers and ice sheets are shrinking and contributing to sea level rise. Ocean warming has been implicated as a driver of glacier retreat, with submarine melting as the presumed link. However, at the termini of tidewater glaciers, we lack observations of submarine melting or the oceanic processes that control melt. Instead, many studies rely on untested theory and parameterizations to estimate submarine melt rates. These frameworks often hinge on buoyant plumes, whose small-scale dynamics can modulate both the ocean’s impact on the glacier via submarine melting and the glacier’s impact on the ocean via buoyancy forcing. In this talk, I will present data collected near the terminus of LeConte Glacier, Alaska to probe the standard theory for plume-driven melt. In the first half, I will present surveys from autonomous kayaks that reveal ubiquitous meltwater intrusions along the terminus and suggest a mechanism to explain melt rates that are significantly higher than standard theory predicts. In the second half, the bulk fluxes of submarine melt and subglacial discharge are evaluated across a wide range of conditions in six field campaigns to test the theoretical relationship between these two sources of freshwater. Modifications to the standard melt parameterizations are explored, in an effort to work towards an updated representation of melt in ocean-glacier models.