Interannual variability in the 1990s in the northern Atlantic and Nordic Seas

Abstract

A global fine resolution curvilinear ocean model, forced by NCEP Re-Analysis fluxes, is used to study changes in the circulation of the Nordic Seas and surrounding ocean basins during 1994–2001. The model fields exhibit regionally distinct temporal variability, mostly determined by atmospheric forcing but in regions of significant sea-ice longer timescale variability is found. Some abrupt circulation changes accompany the relaxation of the westerlies following the peak North Atlantic Oscillation Index phase of the mid 1990s. The Greenland gyre spins up over the following years, with the increased circulation partially exiting through the Denmark Strait into the northern Atlantic as well as re-circulating within the Nordic Seas. This resulted in a distinct freshening around northern Iceland and an increase in the East Icelandic Current. However, these latter increases steadied after 1998, as the increased Greenland Sea gyre circulation led to a greater proportion of water leaving through the Denmark Strait...