Abstract

The circulation of the North Atlantic Deep Water (NADW) in the South Atlantic is determined from hydrographic, nutrient, and tracer data from WOCE and other high quality pre-WOCE sections using a linear box-inverse model. Multiple  linear regression, which makes use of the correlation between different parameters, is applied to infer the missing parameters in the bottle data set. This interpolation technique also enables us to include the nutrient and tracer measurements in the inverse model with a spatial resolution of the corresponding CTD data.
The data define a set of 126 closed boxes on which conservation requirements are imposed. A detailed water mass analysis is performed, incorporating the tracer information from the whole South Atlantic, to determine the vertical boundaries of these boxes. As a result the water column is divided into 11 layers which are defined by neutral densities. Constraints for the inverse model are an integral meridional salt and phosphorus transport, the overall salt and silica conservation, as well as flow conditions inferred from moored current observations. The results are analysed with an emphasis on the zonal spreading of the NADW. A clear meridional separation in the direction of the zonal NADW transports can be observed. Quantitative estimates are given.