CIRCULATION REGIMES IN GREENLAND’S OUTLET GLACIAL FJORDS

The Greenland Ice Sheet (GrIS) is connected to the large-scale North Atlantic Ocean circulation through fjords. These fjords control the amount of heat reaching the GrIS outlet glaciers, and thus the submarine melt rate, and modulate the flows close to the glacier face, where they can mechanically force any ice mélange present or the glacier itself if it is floating. Here, we discuss the circulation regimes of several major outlet glacial fjords in Greenland to gain insight on the primary processes controlling fjord circulation. In most of the deep fjords without shallow sills, we find that synoptic scale, weather driven variability dominates over the buoyancy driven flow. Outside these fjord systems, geostrophic currents are present and are possibly affected by the fjord outflow. We examine simple parameterizations of the main circulation mechanisms, including the relative strength of the estuarine or buoyancy driven flow to the intermediary circulation. An overall picture of fjord variability is emerging from the Greenland observations that can be compared across other fjord/glacier regions, such as the Antarctic Peninsula, SE Alaska, and Chilean Patagonia.