Quantifying the Release, Transport, and Fate of Iceberg Melt in Greenland Fjords

Dustin Carroll, Moss Landing Marine Laboratories, Moss Landing, CA, United States, David Sutherland, University of Oregon, Department of Earth Sciences, Eugene, OR, United States, Mark James Hopwood, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany, Twila A Moon, University of Colorado at Boulder, National Snow and Ice Data Center and Cooperative Institute for Research in Environmental Sciences, Boulder, United States and Dimitris Menemenlis, NASA Jet Propulsion Laboratory, Pasadena, United States
Freshwater flux from ice-sheet mass loss raises global sea level, influences biogeochemical systems and fisheries, and modifies water mass properties, which can feedback into both regional and global ocean circulation. In particular, icebergs calved from marine-terminating glaciers are critical vectors for transporting freshwater and bioessential micronutrients at both local and remote scales. Here we examine the nearfield spatiotemporal structure of iceberg melt using a suite of 3-D, high-resolution (uniform 1 m), non-hydrostatic MIT General Circulation Model (MITgcm) simulations. We use novel shipboard observations collected around icebergs in Sermilik Fjord, southeast Greenland to motivate a set of numerical experiments that test the sensitivity of melt to: iceberg shape and keel depth, summer and winter fjord stratification, and uniform and vertically-sheared ocean currents. Passive tracers released separately into simulated iceberg sidewall and basal melt allow us to quantify the fate of iceberg melt throughout the water column, and are used to assess the role of upwelling vs. horizontal melt intrusions. Ultimately, these results allow for an improved understanding of the release, transport, and fate of freshwater and micronutrient discharge from icebergs.