Ausbreitung von Island-Schottland-Überstromwasser im östlichen Nordatlantik

Abstract

The spreading of Iceland Scotland Overflow Water (ISOW) in the eastern North Atlantic is the focus of this thesis. It is shown that the classical pathway of ISOW through the Gibbs Fracture Zone into the western North Atlantic is not the only one on which it is spreading. Anomalies of salinity, oxygen and silica are used to reveal the influence of ISOW on the northeastern North Atlantic. It can be seen from the anomalies that ISOW has an influ-ence on the water of the Iceland Basin that extends widely over the ISOW core itself. The ISOW influenced water formed by vigorous mixing in the Iceland Basin partially undergoes a anticyclonic recirculation in the northern Westeuropean Basin. Another part is exported to the south along the Midatlantic Ridge.The variability of the ISOW influence on the deep water is examined for the first time using repeat sections. The eastern boundary of the ISOW influence is subject to the biggest changes. These are strongly correlated with the NAOI (correlation coefficients: -0.93 and -0.92). This emerges from a strong coupling of the deep water spreading to the surface currents via baro-tropic velocity components in the northern part of the area of investigation.A quantitative estimate of the transport from the Iceland Basin to the Westeuropean Basin is based on a mixing and transport analysis relying on transient tracers. The transport is calcula-ted to be (1.63 ± 0.32)·10:sup:6:/sup: m³/s in the density range for which the analysis yields stable results (41,37 < :img:=sigma.gif:/img::sub:3:/sub:/(kg/m³) <41,475). The transport for the density range usually considered as deep water (:img:=sigma.gif:/img::sub::img:=Theta.gif:/img::/sub: > 27.8 kg/m³) is estimated to be 2.4 - 3.5·10:sup:6:/sup: m³/s. Considering oxygen and silica in the mixing and transport analysis confirms the results. This means that there is a transport of deep water along this route that is approximately equal to the transport through the Gibbs Fracture Zone.