Quantification of Sub-Shelf Melt Rates and the Effects on Basal Crevasse Propagation along Tidewater Glaciers in Northern Greenland

The primary drivers of mass loss from marine-terminating glaciers are submarine basal melting and iceberg calving. Advancements in both remote sensing and crevasse modelling have made it significantly easier to quantify, 1) the volume of ice loss through calving via direct observation, and 2) the role which basal crevasses play in calving processes. Recent studies correlate the presence of basal crevasses to large-scale calving events along many marine-terminating glaciers; yet both the mechanisms controlling basal crevasse formation and effects which basal melting have on the evolution of crevasse propagation and morphology remains poorly constrained. Understanding the relationships between basal melt, crevasse growth, and both oceanic and atmospheric driving forces is crucial for accurately modeling the responses of tidewater glaciers to a changing climat.

Here we use a combination of airborne radar, LiDAR, and aerial imagery collected by the Center for Remote Sensing of Ice Sheets (CReSIS) and NASA's Operation Ice Bridge (OIB) field campaigns to address these knowledge gaps. Specifically, we quantify interannual changes of grounding-line position, basal crevasse morphology, and ice-tongue thickness for five glaciers in northern Greenland between 1995 and 2017. We compare results from Petermann Glacier (which has numerous basal crevasses) with less-crevassed glaciers (Humboldt, Ryder, Niohalvfjerdsfjorden, and Zachariae Isstrøm) to establish a robust record of sub-shelf changes in northern Greenland. The results of this study will produce a quantitative estimate of submarine melt beneath major northern tidewater glaciers in Greenland, and assess the impact that basal crevasses have on melt rates and calving processes.