A simple model study of the Arctic Ocean freshwater balance, 1979–1985

Abstract

The freshwater budget of the Arctic Ocean from autumn 1979 to autumn 1985 is examined using a simple ice‐ocean model. The ice model, described in detail by Thomas et al. [this issue], uses data from drifting buoys to determine the velocity field and data from passive microwave satellites to determine the concentration field. The resulting fluxes of momentum and salt are then used to drive the ocean model. The model “grid” consists of seven broad regional cells in which we compute average quantities such as salinity profiles. The domain extends down to 200 m depth. The results indicate that the interannual variability of mixed layer salinity (MLS) is greater in the western Arctic than in the eastern Arctic. The interannual variability of MLS in the Arctic Ocean as a whole is quite small in this simulation but is still as large or larger than the trend predicted by Manabe et al. [1991] due to increasing atmospheric CO2. The results of our freshwater analysis indicate that there was an increase of 45% above the mean in the freshwater export through Fram Strait during 1982. This increase occurred in both the sea ice and ocean components, although mostly in the former. A decrease in the freshwater outflow through the Canadian Archipelago (which generally constitutes about 34% of the total) occurred at about the same time. Finally, a simple experiment was run in which river and precipitation fluxes were increased to the level predicted by Manabe et al. [1991] by the end of a 100‐year increased CO2 simulation. The resulting increase in oceanic freshwater flux through the Canadian Archipelago is about 60% more than that through the Fram Strait, which might have an influence on the preferred location for deep water formation in a warmer climate.