Impact of recirculation on the East Greenland Current in Fram Strait: Results from moored current meter measurements between 1997 and 2009

• Published in: Deep-sea research. Part I, Oceanographic research papers Vol. 92; pp. 26 - 40
• Main Authors: de Steur, L., Hansen, E., Mauritzen, C., Beszczynska-Möller, A., Fahrbach, E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2014; Elsevier; Pergamon Press Inc
• Subjects: Arrays; Coastal oceanography, estuaries. Regional oceanography; Current meter measurements; Cyclones; Earth, ocean, space; East Greenland Current; Estimates; Exact sciences and technology; External geophysics; Fram Strait; Latitude; Marine; Measurement; Mooring; Ocean circulation; Ocean currents; Oceanography; Physics of the oceans; Recirculating Atlantic Water (RAW); Recirculation; Scientific papers; Straits; Thermohaline structure and circulation. Turbulence and diffusion; Time series; Transport; Volume transport; East Greenland; Arctic region; Atlantic Ocean; Arctic Ocean; polar regions; North Atlantic; Greenland Current; Greenland; Fram Strait; ANE, Norwegian Sea; ANE, Atlantic, East Greenland Current; PNE, Arctic Ocean, Fram Strait; Recirculation; Current meter measurements; East Greenland Current; Volume transport; Fram Strait; Recirculating Atlantic Water (RAW); time series analysis; ocean currents; Temperature distribution; Water mass; Mooring; Current meter; Velocity distribution; Hydrography; Current measurement; Recirculating flow; Observation data; Polar region; Measuring network; Acoustic Doppler current profiler; ocean circulation
• ISSN: 0967-0637; 1879-0119
• DOI: 10.1016/j.dsr.2014.05.018

Transports of total volume and water masses obtained from a mooring array in the East Greenland Current (EGC) in Fram Strait are presented for the period 1997–2009. The array in the EGC was moved along isobaths from 79°N to 78°50′N in 2002 to line up with moorings in the eastern Fram Strait. Analysis of the time series at the two latitudes shows that associated with the southward move, the annual mean volume transport of the EGC increased from 5.8±1.8Sv to 8.7±2.5Sv, mostly related with an increase in barotropic flow. This suggests a recirculation of close to 3Sv at 78°50′N as a consequence of the large-scale wind-driven cyclonic gyre in the Nordic Seas. In addition, the volume transport at 78°50′N showed a clear seasonal cycle which was absent at 79°N. Estimates of the wind-driven Sverdrup transport at two different latitudes show that the difference in total volume transport and seasonality can largely be explained by the wind-stress curl. However, weak transport in 2003 was only partially related with weak Sverdrup transport and coincided also with anomalously weak northerly winds. The stronger recirculation at 78°50′N has also consequences for the observed Atlantic Water: there is significantly more Atlantic derived water present at the southerly latitude. In addition, the warm anomaly in Fram Strait between 2005 and 2007 doubled the amount of Recirculated Atlantic Water temporarily. Finally, we estimate that close to 2.7Sv, or 50%, of Atlantic derived water recirculates in Fram Strait. •Due to recirculation the volume transport at 78°50′N is 3Sv larger than at 79°N.•Larger recirculation at 78°50′N results in a significant seasonal cycle in the EGC.•Differences in recirculation and seasonality are explained by the wind-stress curl.•2.7Sv, or 50%, of the Atlantic derived water recirculates in Fram Strait.