The role of Regional Atmospheric Circulation in Interannual Variability of the Ocean Heat Advection in the Nordic Seas

Abstract

More than 90% of oceanic heat enters the Arctic Ocean with the Norwegian Current. In this paper we examine the mechanisms of variability of the oceanic heat flux in the Norwegian Current (across the Svinoy section in the southern Norwegian Sea) in 1993–2019. GLORYS oceanic reanalysis with a spatial resolution of 1/12° is used. It is found that the variability of oceanic heat flux is associated with that of water transport, which, in turn, is associated with variability of the sea level gradient across the Norwegian Current. It is shown that an increase in water transport of the Norwegian Current is a result of a decrease of the atmospheric pressure over the central part of the Norwegian Sea. The latter intensifies the southwesterly winds along the Scandinavian Peninsula. The sea level gradients across the Norwegian Current, formed by the winds, are primarily associated with Ekman pumping towards the coast, as well as with the wind stress curl. Both have a significant impact on the variability of water transport through the section. Another factor is variability of the steric sea level gradient, which significantly affects the water transport during the period of a rapid temperature rise of in the Norwegian Current (1995–2005).