OVIDE : Rapport de données Eulériennes

Complementing the study of the variability of the North Atlantic Subpolar Gyre that is performed in the frame of the Ovide project, the East Greenland/Irminger Current (EGIC) was measured at 60°N between June 2004 to June 2006 by an array of 5 moorings, placed on a section from the shelf to the 1900m isobath. The moorings were equipped with 15 RCM currentmeters and 2 ADCPs to measure the volume transport, and also 5 micro-CTD at mooring heads (about 200m below the surface) to measure the vertical displacement of the moorings and the variability of the warm and salty water masses in the Irminger Current. The highest velocities, about 80 cm/s, are found at the top of mooring B. The core of the current is located between moorings B and C. The current direction is quite constrained by the bathymetry, revealing that the errors on heading measurements are sensibly higher than those mentioned in the instrument specifications. The pressure data revealed that the deformation of the mooring line was under-estimated under strong currents, but no effect was noticed on the quite good quality of the data. The “Ifremer” section array was extended offshore during the second year by a “NOC” array of 7 deep moorings in order to measure the Deep Western Boundary Current (CFER project of S. Bacon); the mooring on the 2100m isobath was equipped with 3 of LPO’s instruments in the first 1000m. A very good data return was obtained, with an overall rate of 90% (omitting the new instruments under testing). A first article is in preparation (Daniault et al.), and the deep currentmeters of moorings A and B were used by Bacon and Saunders (JPO 2009).