Dynamics of Greenland’s Glacial Fjords

Rebecca Jackson, Ph.D., 2016
Fiamma Straneo, Advisor

Glacial fjords, which link the Greenland Ice Sheet and the North Atlantic, are gateways for importing oceanic heat to melt ice and for exporting meltwater into the ocean. Submarine melting has been implicated as a driver of recent glacier acceleration; however, there are no direct measurements of this melting, and little is known about the fjord processes that modulate melt rates. Combining observations, theory and modeling, this thesis investigates the circulation and heat/meltwater transport in glacial fjords. With moorings from two Greenlandic fjords, shelf forcing is found to dominate the fjord circulation, driving rapid exchange with the shelf and large temperature variability near the glacier. Building on estuarine studies of salt fluxes, this thesis presents a new framework for assessing glacial fjord budgets and revised equations for inferring meltwater fluxes from the glacier. These methods are applied to moored records from Sermilik Fjord, revealing two different seasonal regimes in the fjord budgets and providing the first timeseries of meltwater fluxes into a glacial fjord. Finally, building on the observations, ROMS numerical simulations and two analytical models are used to investigate the dynamics of shelf-driven flows and their importance relative to local wind forcing across the parameter space of Greenland's fjords.