Influence of the Norwegian Sea Gyre on the heat transports to the Arctic

Recent studies promise a potential for predicting the oceanic transport of heat into the Arctic, which in turn regulates the coverage of sea ice and subsequently impacts the atmospheric dynamics with possible tele-connective feedbacks to the mid-latitude weather systems. We here show that deep-reaching anticyclonic circulation anomalies in the Norwegian Sea Gyre (NSG) oppose both the poleward Atlantic Water heat transports and the southeastward flow of subarctic water from the Iceland Sea into the southern Norwegian Sea. Both aspects result in an increased lateral spread of warm Atlantic Water – and thus increased storage of heat – within Norwegian Sea. After having been transformed and densified within the Arctic Mediterranean, the Atlantic water returns equator-ward as deep overflow - with a main branch passing through the Faroe Bank Channel (FBC). We reveal a close correlation between a FBC overflow record and the observed sea surface height east of Iceland, and suggest that both reflect the circulation directionality of the NSG. These time series can therefore be used as independent, robust high-temporal resolution metrics for regional volume storage of Atlantic and subarctic waters - and thus the depth of the main pycnocline that separates these – which all are fundamental aspects of the marine climate and the ecological conditions within the Norwegian Sea.