Observations of Iceberg Meltwater Distribution in Sermilik Fjord, Southeast Greenland

Margaret Ruth Lindeman, Scripps Institution of Oceanography, La Jolla, United States, Fiammetta Straneo, Scripps Institution of Oceanography, La Jolla, CA, United States, Hanumant Singh, Northeastern University, Department of Electrical & Computer Engineering, Boston, MA, United States, Claudia Cenedese, WHOI, Woods Hole, MA, United States, David Sutherland, University of Oregon, Department of Earth Sciences, Eugene, OR, United States, Kristin M Schild, University of Maine, Earth and Climate Sciences, Orono, ME, United States and Dan Duncan, University of Texas, Institute for Geophysics, Austin, TX, United States
As much as half of the freshwater flux from the Greenland Ice Sheet enters the ocean through iceberg calving. Up to 50% of iceberg mass is expected to melt within glacial fjords, where it influences the circulation and properties of water masses in contact with the glacier terminus, as well as the characteristics of glacially-modified water exported to the North Atlantic. Observations of iceberg melt in fjords are needed to evaluate predictions of spatial and temporal meltwater distribution under a range of environmental conditions, in order to determine its impacts on the ocean.

We conducted repeat oceanographic surveys of 6 icebergs in Sermilik Fjord, southeast Greenland, during August 2018 to identify environmental factors driving the distribution of iceberg melt, including ocean thermal forcing and stratification, relative velocity between each iceberg and local ocean currents, and iceberg geometry. Our surveys include near-iceberg properties sampled using a remotely-operated surface vehicle (Jetyak) equipped with an ADCP (Acoustic Doppler Current Profiler) and temperature and salinity sensors, as well as full-depth temperature and salinity profiles. Iceberg depth and shape were measured using multibeam sonar and aerial imagery, and some iceberg locations were tracked with GPS. We compare our findings to numerical and laboratory simulations, and discuss their implications for iceberg melt distribution in the context of a decade-long observational record of ocean variability in Sermilik Fjord.