The Big Picture
Tidewater glaciers are huge rivers of ice which transport ice mass from the interior of the Greenland Ice Sheet, through spectacular fjords and eventually into the ocean where the ice is lost either to melting by the ocean or the production of icebergs. In a healthy ice sheet these losses - plus summer surface melting – are balanced by mass gain due to snowfall during winter.
In recent decades, tidewater glaciers around Greenland have accelerated dramatically, with some glaciers more than doubling in flow velocity. These changes have perturbed the mass balance of the ice sheet, adding approximately 4 mm to global sea level over the past two decades. Understanding the cause of these changes is an ongoing topic of research, with a warming of the ocean surrounding Greenland a leading candidate.
My work centers on trying to understand the processes controlling the interaction between the ocean and the Greenland Ice Sheet. Given the dramatic changes at tidewater glaciers in recent decades, and projected future ocean warming, understanding such processes is vitally important if we are to accurately forecast the contribution of the ice sheet to sea level, and provide the scientific input that is required to make the best sea level adaptation and mitigation decisions.
Numerical ocean modelling
I use the numerical ocean model MITgcm to simulate near-calving front circulation induced by the drainage of fresh subglacial discharge from beneath tidewater glaciers. The buoyant plumes which result are thought to drive high rates of melting of the ice by the ocean. Resolving the dynamics of these plumes requires high resolution, non-hydrostatic simulations. I have used these simulations to investigate how the subglacial hydrology of the glacier affects melting of the calving front, and tried to constrain the subglacial hydrology of a tidewater glacier based on the appearance of sediment plumes in the fjord. I am currently using the MITgcm to model wider fjord circulation in a small fjord in west Greenland for comparison to an extensive hydrographic and circulation dataset.
Buoyant plume theory
I have worked extensively with simpler models of plumes, which allow the study and parameterization of plume dynamics and melting without the high computational cost of circulation models like MITgcm. I have used these models to develop simple scaling laws for how the melting induced by plumes responds to atmospheric and oceanic warming. I also developed a model for how plumes undermine calving fronts through melting.