Space–time behaviour of the Angola–Benguela Frontal Zone during the Benguela Niño of April 1999

Abstract

The hydrographic conditions in the south-east Atlantic were investigated during the cruise of R/V Poseidon in April 1999. The area of investigation covers the two major eastern boundary currents of the Southern Atlantic and its convergence in the Angola–Benguela Frontal Zone (ABFZ). Hydrographic measurements have been carried out in combination with current measurements and are supplemented with remote sensing data of sea surface temperature (SST) and wind stress.

The Angola Current transported in its surface part less saline water from the great rivers in the north towards the ABFZ. At the same time, south of the front, strong coastal upwelling in the Benguela was observed. At the beginning of April 1999 the ABFZ was found at an unusual southern position. The rapid dynamic response of the ABFZ to wind forcing is discussed on the basis of satellite SST images combined with hydrographic measurements.

Acknowledgments

The cruise participants thank all individuals and authorities who gave valuable support and encouragement in the preparation of the cruise with R/V Poseidon. This cruise was granted by the ‘Bundesminister für Bildung und Forschung’ (BMBF 03F154A) and the ‘Gesellschaft für Technische Zusammenarbeit’ (GTZ, 81024061). Help and support of the ship's crew is gratefully acknowledged.

We thank Scarla Weeks of OceanSpace for meticulous data processing in preparing the thermal infrared images. The contribution by JREL was funded by the National Research Foundation and the University of Cape Town. We thank also CERSAT at IFREMER and the IRI/LDEO Climate Data Library for providing satellite data on their web page.

Notes

An updated version of a paper originally presented at Oceans from Space ‘Venice 2000’ Symposium, Venice, Italy, 9–13 October 2000.