Synoptic estimates of an eddy field in the north-atlantic current

• Main Author: Demey, P
• Format: Article in Journal/Newspaper
• Language: English
• Published: Gauthier-Villars 1992
• Subjects: north atlantic current; North Atlantic
• Online Access: https://archimer.ifremer.fr/doc/00101/21240/18855.pdf; https://archimer.ifremer.fr/doc/00101/21240/

We show various synoptic estimates of the North Atlantic Current (NAC) eddy field in a domain 450 x 350 km at 52.5-degrees-N 25.0-degrees-W in the theoretical path of the NAC. Temperature, salinity, and surface streamfunction estimates are derived from the AthenA hydrological data collected in the summer of 1988. These estimates are discussed and compared with two surface streamfunction estimates obtained from Geosat altimetric measurements: one statistical, and the other resulting from quasi-geostrophic assimilation. The estimates show a frontal structure associated with a jet, sharply separating cold and fresh water to the north from warmer and saltier water to the south. Temperature and salinity values on both sides of the front are consistent with climatological values. The assimilation estimates indicate that there may have been an eddy merger event during the experiment. The eddy field is much more energetic than the mean; no clear propagation is evidenced; time scales are longer than twenty days. Local transport by the jet as calculated from model results is of the order of 30 x 10(6) m3 s-1; the vertical structure is that of the ''sheared barotropic mode'', where transport has the same sign and direction from top to bottom, but is weaker at the bottom.