Seismic oceanography comprises a new field within Geophysics where reflections within the water column are investigated. It was shown that those reflections correspond to thin layers with strong vertical temperature gradients. Those reflections hence represent a chance to trace those temperature gradients over large distances.Weak seismic reflections within the water column south of South Africa gave rise to the question whether here traces of the Agulhas Current or Agulhas Retroflection can be observed. A careful reprocessing of the data led to the imaging of fields of reflections pointing towards a 135 km broad and about 1000 m deep reaching well stratified area with strong reflection amplitudes and several weaker reflections extending down to at least 1500 m water depth over the whole area of investigation.To image both the boundaries between the water masses as reflections and the different properties of the long wavelength velocity variations in depth special imaging technigues like prestack depth migration analysis were performed. Further, the temperature gradients from the short wavelength properties as velocity and density contrasts were determind by a two step inversion of acoustic amplitude versus angle analysis to better quantify the variations of the water masses of the Agulhas Current.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > MAR2-Palaeo Climate Mechanisms and Variability