Der Transport von Wärme, Wasser und Salz in den Arktischen Ozean

Abstract

The combination of high resolution hydrographic and velocity measurements at identical grid points allows to avoid interpolation problems involved in the evaluation of mooring measurements. The mean circulation of the Greenland Sea is dominated by a large cyclonic and predominantly barotropic gyre. The calculated absolute velocities across the 75°N standard section question the existence of Koltermann´s (1991) postulated deep anticyclonic gyre. At 75°N the East Greenland Current (EGC) is identified over a distance of 140 km as a narrow jet which carries ice and polar water to the South. The total volume transport calculated for the region of the EGC is comparable with results of moored current meters and ranges between 12 and 29 Sv (Fahrbach et al., 1995 and Woodgate et al., 1999). In contrast to the EGC the Westspitsbergen Current (WSC) carries Atlantic Water (AW) to the North and exhibits a much larger mesoscale variability. The velocity field in the WSC is characterized by variable meanders and mesoscale eddies with typical horizontal dimensions of 50 km, whereas jet-like structures dominate in the EGC. Since the AW provides the major contributions to the meridional heat transport five realizations of the 75°N standard section were used to investigate its interannual variability. During the summers 1990 - 1998 the AW transports ranged between 2 and 7 Sv. The total heat transport across 75°N is estimated as 52 TW in September 1997 and 42 TW in September 1998. The total salt transport ranges between 5.2 and 5.6 e6 kg/s. Finally based upon five hydrographic sections taken between 70°N - 82°N and 25°W - 25°E during August/September 1997 a circulation and transport scheme for the principle water masses is constructed and compared to the results of Mauritzen´s inverse box model (Mauritzen, 1994). Both transport schemes are in good agreement. Between 75°N and 79°40´N the mean temperature of the AW decreases by 0.8°C while its density increases.