Title: Where glaciers meet the ocean: testing theories for submarine melt with observations from autonomous vessels

Speaker: Dr. Rebecca Jackson, Tufts University

Abstract:
Around the globe, glaciers and ice sheets are shrinking, raising sea levels at an accelerating rate.
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 – where glaciers meet the ocean with
a near-vertical ice cliff – 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 freshwater input. In this talk, I will present data collected near
the terminus of LeConte Glacier, Alaska. Autonomous vessels surveyed and deployed moorings
near the glacier, in a region that is otherwise inaccessible due to iceberg hazards, while
simultaneous measurements were collected downstream with a ship and upstream on the glacier.
We assess the structure and dynamics of an upwelling plume, the internal wave field that the
plume excites, and the links between plumes, submarine melting, and glacier dynamics. We
propose modifications to the standard approach for parameterizing melt, aiming to improve
models of ocean-glacier interactions and work towards more accurate projections of sea level rise.