Seasonal to inter-annual variability of temperature and salinity in the Greenland Sea Gyre: heat and freshwater budgets

摘要

Six years of autonomous profiling float data from the Greenland Sea Gyre are used to detect changes in temperature and salinity of the water column on time scales from seasonal to inter-annual. The effect of ocean-atmosphere and internal ocean fluxes on heat and freshwater is largely (about 90%) confined to the upper 700 m. Throughout the water column a warming at a mean rate of 0.05 K year~(-1) is observed, whereas the freshwater content is dominated by inter-annual changes not containing trends. In the annual mean the Gyre exports freshwater across its boundary throughout the water column. Import of freshwater takes place only in the upper 50 m during summer. Heat is exported in the upper 50 m, while below the gyre cools the surrounding. The net effect of the gyre on the water mass conversion in the Arctic Mediterranean is small and the gyre does not re-enforce the Nordic Seas overturning circulation.