The Role of Fjord Topography on Submarine Melting of Greenland’s Glaciers: a Laboratory Study

Increased submarine melting of Greenland’s glaciers has emerged as a plausible trigger for their recent acceleration and for the quadrupling of Greenland’s contribution to sea-level rise from 1992-2000 to 2001-2011. Despite this, our understanding of submarine melting is limited and is presently absent or crudely parameterized in glacier, ice sheet and climate models. Idealized laboratory experiments have been conducted to investigate the leading order dynamics that control submarine melting and the meltwater export near a vertical ice/ocean interface as a function of ambient properties and stratification, subglacial discharge characteristics and fjord topography, in particular the presence and height of a sill. In summer, the discharge of surface runoff at the base of a glacier (subglacial discharge) generates strong buoyant plumes that rise along the glacier front entraining ambient water along the way. The entrainment enhances the heat transport towards the glacier front and hence the submarine melting. The presence of a sill in the tank influences the evolution of the stratification near the glacier and consequently affects the submarine melting. We will discuss the relevant dynamics and their implication for parameterization of these processes in Earth System Models. Support was given by NSF project OCE-1434041