Internal overflow in the Nordic Seas and the cold reservoir in the northern Norwegian Basin

Abstract

Based on hydrographic data collected in 2014 in the area around Jan Mayen, the waters flowing out from the Greenland Sea to the Norwegian Sea through the Jan Mayen Channel (JMCh) and their potential contribution to the Greenland-Scotland Ridge overflow are investigated. The results show that only the waters flowing along the southern periphery of the Greenland Sea can enter the Norwegian Sea through the JMCh. These waters are composed of low-salinity water in the upper layer, slightly saline Return Atlantic Water in the middle layer, and the Greenland Sea Arctic Intermediate Water in the lower layer of the Jan Mayen Current. The depths of these waters increase by approximately 150–200 m upon entering the Norwegian Sea, forming an internal overflow within the Nordic Seas. The density range of waters entering the Norwegian Sea through this internal overflow is between σθ = 28.02 and 28.06 kg m−3. These waters accumulate below 330 m with an east-west extent exceeding 160 km, forming a large, cold reservoir in the Norwegian Basin. In 2014, the cold reservoir water properties were highly consistent with the properties of the dense water located between 550 and 1000 m in the Faroe-Shetland Channel (FSC), which suggests that the cold reservoir may be an important source of the overflow water through the Faroese Channels, and could play a role in stabilizing and sustaining continuous overflows.