Episodic formation of intermediate water along the Greenland Sea Arctic Front

Abstract

During CTD and plankton surveys in the Nordic Seas in November 1991 - 1994, a CTD section has been worked across the Arctic Front between the Lofoten and Greenland Basins. Along this front Isopycnic surfaces slope down from upper layers on its cold side in the Greenland Basin to intermediate depths of 800 to 1000 m in the warmer waters of the Lofoten Basin. While it earlier has been concluded that intermediate water masses are formed in the Greenland and Iceland Seas during winter, it has not been clear whether intermediate water sinks in to the Norwegian Sea along the Arctic Front to the northeast of Jan Mayen. The present sections show that such formation may occur in November. This is indicated by narrow filaments of water which is less saline than the ambient water. This water seems to be brought to the front by mesoscale eddies on its cold side. The heaviest water is supplied at depths between about 100 and 500 m. It is therefore not affected by summer warming so that sinking plumes may in principle occur in all seasons. The occurrence of such plumes in two of the four sections suggest that such events may be rather frequent although they are episodic. In general, this may therefore be an important mechanism for formation of intermediate water.