The physical oceanographic processes on the southeast African shelf and slope
Situated between the southeast coast of South Africa and the western edge of the Agulhas Current, is the southeast African shelf. The Agulhas Current, like other western boundary currents of the world, strongly influences the oceanographic conditions of its adjacent shelf system. Limited societal dr...
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| Other Authors: | , , |
| Format: | Master Thesis |
| Language: | English |
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Faculty of Science
2018
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| Online Access: | http://hdl.handle.net/11427/29993 https://open.uct.ac.za/bitstream/11427/29993/1/thesis_sci_2018_russo_cristina_serena.pdf |
| Summary: | Situated between the southeast coast of South Africa and the western edge of the Agulhas Current, is the southeast African shelf. The Agulhas Current, like other western boundary currents of the world, strongly influences the oceanographic conditions of its adjacent shelf system. Limited societal drivers have resulted in the southeast African shelf being one of the least studied and under-sampled shelf systems in southern Africa. The in situ sample deficit has led to the majority of studies conducted in this region to be carried out using satellite data and modelling. In order to identify the physical oceanographic processes occurring on the southeast African shelf and slope, as well as the influence that the Agulhas Current has on them, this study analysed satellite data combined with high resolution in situ data, acquired during two hydrographic surveys of the southeast African shelf and slope, during January/February (austral summer) and July/August (austral winter) 2017. The Agulhas Current as well as a number of physical processes were observed to influence the shelf region. The snapshot of the two seasons given by the January/February and July/August in situ data presented indications of seasonality of temperature and salinity within the upper water masses but not within the deeper water masses. The same five water masses, Tropical Surface Water (TSW), Subtropical Surface Water (STSW), South Indian Central Water (SICW), Red Sea Water (RSW) as well as Antarctic Intermediate Water (AAIW), were observed during each cruise. As a result of the westward widening shelf from just east of East London, divergence-induced upwelling was observed between the coast and the inshore edge of the Agulhas Current, during both January/February and July/August. Ekman veering in the bottom boundary layer was observed between Port Alfred and East London during January/February as a result of the close proximity of the Agulhas Current to the slope. Altimetry data indicated the presence of a cyclonic eddy during both the ... |
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