The Iceland-Faroe inflow of Atlantic water to the Nordic Seas

• Published in: Progress in oceanography Vol. 59; no. 4; pp. 443 - 474
• Main Authors: HANSEN, B, ØSTERHUS, S, HATUN, H, KRISTIANSEN, R, LARSEN, K. M. H
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.12.2003
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Marine; Physics of the oceans; Thermohaline structure and circulation. Turbulence and diffusion; Greenland Sea; Norwegian Sea; Atlantic Ocean; Faroe Islands; Arctic Ocean; Atlantic Ocean Islands; Iceland; ANE, Norwegian Sea; AW, Atlantic; ANE, Atlantic, Iceland; ANE, Atlantic, Faeroe Is; ANE, Iceland; PN, Arctic Ocean; MED; ANE, Atlantic, Faeroe-Shetland Channel; ANE, Atlantic, Greenland-Scotland Ridge; Water mass; Ocean circulation; Mooring; Velocity distribution; Ocean dynamics; Water flow; Salinity; Ship observation; Marine hydrography; Current measurement; Seasonal variation; Sea current; Heat mass transfer; Observation data
• ISSN: 0079-6611; 1873-4472
• DOI: 10.1016/j.pocean.2003.10.003

The flow of Atlantic water between Iceland and the Faroe Islands is one of three current branches flowing from the Atlantic Ocean into the Nordic Seas across the Greenland-Scotland Ridge. By the heat that it carries along, it keeps the subarctic regions abnormally warm and by its import of salt, it helps maintain a high salinity and hence density in the surface waters as a precondition for thermohaline ventilation. From 1997 to 2001, a number of ADCPs have been moored on a section going north from the Faroes, crossing the inflow. Combining these measurements with decade-long CTD observations from research vessel cruises along this section, we compute the fluxes of water (volume), heat, and salt. For the period June 1997-June 2001, we found the average volume flux of Atlantic water to be 3.5+/-0.5 Sv (1 Sv=10 super(6) m super(3).s super(-1)). When compared to recent estimates of the other branches, this implies that the Iceland-Faroe inflow is the strongest branch in terms of volume flux, transporting 47% of the total Atlantic inflow to the Arctic Mediterranean (Nordic Seas and Arctic Ocean with shelf areas). If all of the Atlantic inflow were assumed to be cooled to 0 degree C, before returning to the Atlantic, the Iceland-Faroe inflow carries a heat flux of 124+/-15 TW (1 TW=10 super(12) W), which is about the same as the heat carried by the inflow through the Faroe-Shetland Channel. The Iceland-Faroe Atlantic water volume flux was found to have a negligible seasonal variation and to be remarkably stable with no reversals, even on daily time scales. Out of a total of 1348 daily flux estimates, not one was directed westwards towards the Atlantic.