| Summary: | Degree: Doctor of Philosophy Abstract: The Arctic is currently undergoing significant changes due to increasing anthropogenic greenhouse gases causing atmospheric warming. The impact of this warming is clearly visible in the Arctic: reduced sea-ice cover, enhanced land-ice melting, increased frequency of extreme weather, etc. Understanding the current dynamics of the Arctic Ocean and its exchange with the North Atlantic is the first step in understanding how it may change in the future. In this thesis, I focused on key regions where exchange between the Arctic Ocean and the North Atlantic occurs: Baffin Bay, the Canadian Arctic Archipelago, and the Arctic gateways. I used a numerical model with several domains, resolutions, atmospheric forcings, and runoff datasets to evaluate how Arctic outflow dynamics change or are impacted by the warming climate. I demonstrated (1) that enhanced Greenland melt significantly impacts the steric height in Baffin Bay, which changes the circulation in Baffin Bay, reducing the Arctic outflow through Baffin Bay. (2) The Canadian Arctic Archipelago throughflow is significantly impacted by sea-ice motion as sea-ice has a significant impact on the surface stress. In particular, I showed that more mobile ice enhanced the freshwater transport. (3) The main frequencies acting on the Arctic outflow variability are the seasonal cycle, and the 6-month, 3 year, 6 year, 8.5 year, and 21 year cycles. Variability on short timescales are associated with the atmospheric circulation via the Arctic Oscillation, while longer timescales are related to the variability of the sea surface height gradient between the Beaufort Gyre and Baffin Bay.
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