Influence of Runoff and Subglacial Discharge on Heat Transport in a Subpolar Fjord (Godthåbsfjord, 64°N) in Contact with the Greenland Ice Sheet

Deep fjords around Greenland connects coastal water masses with the Greenland Ice Sheet. Runoff from surrounding drainage areas, including glacier ice, contribute to relatively low-saline surface water in the fjords but also calving and subglacial discharge from tidewater outlet glaciers affect water properties and fjord circulation. Relatively warm bottom water masses have been observed in front of tidewater outlet glaciers where they provide energy for subsurface melt. Thus, feedbacks between ocean heat transport and melting of tidewater outlet glaciers are critical for determining glacier melt rates and their stability in a warmer climate. Here we analyze a regional model of a Subpolar fjord (Godthåbsfjord, 64°N), located at the west coast of Greenland and in direct contact with the Greenland Ice Sheet via three tidal outlet glaciers. We apply observations from the fjord and surrounding coastal areas to analyze model simulations of temperature, salinity and δ¹⁸O. The model includes the largest freshwater sources from runoff in the area and subglacial freshwater discharge from three tidewater outlet glaciers, where entrainment of bottom water is taken into account, are included explicitly in the boundary conditions. A model sensitivity study analyze the influence of subglacial discharge and runoff on heat transports towards the glaciers and model results are compared with observations.