Spatio-temporal Variability in the Glacier-Ocean Boundary in Central West Greenland

Abstract:

Outlet glacier termini represent the boundary between ice and ocean systems. As such, spatio-termporal differences in terminus shape and position may be indicative of how the ice and ocean systems interact. We examine over 40 years of remote-sensing imagery collected by multiple satellites to characterize the termini of 15 outlet glaciers in Central Western Greenland with unprecedented detail. Our record consists of an average of ~300 terminus observations per glacier; during the last 5 years, we average ~20 observations per year. We find that many glaciers in this region initiated retreat around 1998, coincident with retreat further south at Jakobshavn Isbræ, although the rate and duration of retreat varies from glacier-to-glacier. We explore variations in retreat rate and extent by examining individual fjord geometries, namely changes in fjord width and depth from available ship-based sounding observations. We also explore variations in retreat rate by examining spatial variations in surface melt-induced terminus ablation using a buoyant plume model coupled with field observations. Finally, we identify glaciers in the region that did not undergo significant retreat and examine the balance of forces that may be responsible for their stability.