Increases in the temperature and salinity of deep and intermediate waters in the West Spitsbergen Current region in 1997–2016

This study investigated the temporal variability in the basic physical properties of deep and intermediate waters in the West Spitsbergen Current region at 76°30’N latitude from 1997 to 2016. Emphasis was placed on quantifying the changes in temperature and salinity and determining the potential drivers of these changes. Hydrographic data were obtained during annual summer cruises aboard the r/v Oceania in the Nordic Seas. The increase in the water temperature, which was especially strong in the western part of the investigated section, was associated with considerable changes in the water layers salinity. The temperature and salinity of the intermediate water increased much faster (0.021°C yr−1 and 0.0022 yr−1, respectively) than those of the deep water (0.009°C yr−1 and 0.0004 yr−1, respectively). The warming rate in the upper 2000 m was also higher than the mean warming rate of the global ocean. The source of the deep water temperature and salinity increases was the deep water inflow from the Arctic Ocean into the Greenland Sea. In contrast, the increase in these properties in the intermediate water was associated with the advection of warmer and more saline Atlantic Water from the North Atlantic to the Nordic Seas.