Evolution of Glacial Meltwater in the North Atlantic Current - Subpolar Front System

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The melting of the great ice sheets of the last Ice Age caused sea level to rise by about 130 m globally. In this project a computer model will be developed to simulate the pathways of glacial water introduced into the North Atlantic Ocean from the Laurentide Ice Sheet – the great ice sheet that covered northern North America during the last Ice Age. The project will include modeling of small-scale eddies and their influence on glacial water movements which will help in the understanding of the ocean’s response to ice sheet changes. The results will be important for understanding the role of glacial waters released today from other ice sheets such as the Greenland Ice Sheet. The project will support a graduate student and three undergraduate students, and a how-to manual will be produced so that scientists can use or adapt the model for other projects.A numerical model which represents ocean circulation and sea ice and which resolves ocean mesoscale eddies will be developed to produce detailed simulations of the evolution of glacial water in the North Atlantic Current-Subpolar Front system. Focus will be on glacial meltwater which emanated from the Laurentide Ice Sheet at different locations along the Labrador Shelf, where evidence for ice streams delivering material into the sub-polar gyre exists, and through Fram Strait, which will allow representation of a source of meltwater from the Arctic Ocean, and in particular the Mackenzie River. Two questions will be addressed: (1) To which extent are the temperature and salinity of glacial waters modified as they flow towards deep-water formation areas in the northern North Atlantic? (2) Which processes (eddy-induced mixing or air-sea interactions) most effectively modify the properties of glacial waters en route to these areas? The work plan to address these questions is threefold. First, a coupled ocean circulation-sea-ice model will be configured to represent the subpolar North Atlantic. Second, the coupled model will be tested by using modern observations from oceanographic cruises, hydrographic climatologies, and satellite missions. Finally, experiments with the coupled model will be conducted and analyzed to quantify the erosion of glacial water properties en route to deep-water formation regions and evaluate the role of different eroding factors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.