2007 Annual Meeting and Arctic Forum | Abstracts

Interannual Variability in the Arctic Ocean Freshwater Balance

Alexandra Jahn¹, Bruno Tremblay², Lawrence A. Mysak^3
1Department of Atmospheric and Oceanic Sciences, McGill University, Burnside Hall Room 945, 805 Sherbrooke Street West, Montreal, QC, H3A 2K6, Canada, Phone 514-398-7448, Fax 514-398-6115, alexandra.jahn@mail.mcgill.ca
²Department of Atmospheric and Oceanic Sciences, McGill University, Burnside Hall Room 945, 805 Sherbrooke Street West, Montreal, QC, H3A 2K6, Canada, Phone 514-398-4369, Fax 514-398-6115, bruno.tremblay@mcgill.ca
³Department of Atmospheric and Oceanic Sciences, McGill University, Burnside Hall Room 945, 805 Sherbrooke Street West, Montreal, QC, H3A 2K6, Canada, Phone 514-398-3768, Fax 514-398-6115, lawrence.mysak@mcgill.ca

The Arctic Ocean has a relatively low salinity compared to other oceans, due to the large amount of runoff it receives. Hence, the export of large quantities of fresh arctic surface water and sea-ice are a source of freshwater (water with a salinity of less than 34.8) for the northern North Atlantic. Because the thermal expansion coefficient for sea water at low temperatures is very small, salinity plays a more important role than temperature for the stratification of the water column in the high latitude oceans. As a consequence, large variations in the freshwater export from the Arctic Ocean can lead to decreased deep water formation and a weaker meridional overturning circulation. As changes in the meridional overturning circulation can affect the climate world-wide, a better understanding of the mechanisms which cause these variations in freshwater export is important.

We present a detailed characterization of the freshwater budget of the Arctic Ocean and exchanges with the northern North Atlantic, as simulated by a high resolution version of the University of Victoria Earth System Climate model (UVic-ESCM). This analysis includes a 50-year average present-day freshwater budget for the Arctic Ocean as well as a thorough analysis of the interannual variability of the different terms of the Arctic Ocean freshwater balance (i.e., runoff, net precipitation, Bering Strait inflow, sea ice export, and liquid freshwater export) over the period 1950-2005. We show how this variability is related to atmospheric modes, and how atmospheric modes influence different components of the freshwater balance in the Arctic Ocean.