Frozen fringe below a subglacial hydrologic system

Abstract:

The interactions between ice and sediment at the base of glaciers facilitate the fast flow of ice streams and restrain the slow flow of glaciers that are frozen to their bed. In particular, water flow along the ice-sediment interface controls the strength of the sediments and the infiltration of ice into the sediments, forming what is known as a frozen fringe. Here we investigate the interplay between a subglacial hydrologic system and the formation of a frozen fringe. Using outputs from subglacial hydrology models, we determine the frozen fringe depth beneath idealized ice streams and mountain glaciers. Our results show the development of meter-scale topography that adjusts dynamically with changes in the subglacial hydrologic system. Such dynamic variation leads to changes in the basal friction, highlighting the importance of a physics-based understanding of ice-sediment processes for predictive ice sheet models.