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Ocean governance and the blue economy
Published in Peter B. Myles, Maritime Clusters and the Ocean Economy, 2017
Conservation efforts need to be facilitated by cooperation among countries to have any real chance of combating the potentially severe biodiversity losses that a changing climate might impose – and Africa is no exception. As an example for a region of its size, the coastal and marine environment around South Africa is regarded as one of the most varied in the world, largely due to the dynamic presence of two major currents. The Agulhas Current flows strongly to the southwest along the eastern and southern coasts, bringing warm water and diverse tropical species from the Indian Ocean. The Benguela Current flows northward along the west coast, with wind-driven upwelling close inshore permitting cold nutrient-rich water to rise to the surface, and giving rise to productive coastal ecosystems and fisheries.
Surface currents in operational oceanography: Key applications, mechanisms, and methods
Published in Journal of Operational Oceanography, 2023
Johannes Röhrs, Graig Sutherland, Gus Jeans, Michael Bedington, Ann Kristin Sperrevik, Knut-Frode Dagestad, Yvonne Gusdal, Cecilie Mauritzen, Andrew Dale, Joseph H. LaCasce
The estimation of geostrophic currents via Sea Surface Height (SSH) from satellite altimeter has a long standing (e.g. Bernstein et al. 1982). To first degree, the SSH is equivalent to the earth's geoid and is highly correlated with seafloor variability. By combining all data collected over several years, models of the static geoid gradually improved (Marsh and Martin 1982). This allowed more accurate determination of the residual: the dynamic variation of the topography which is due to ocean circulation. Thus, under the assumption of geostrophically balanced large-scale currents, the current is inferred from the gradient of sea surface elevation. Le Traon et al. (2015) provides a summary of recent progress and future challenges. Jeans and Lefevre (2008) describe the successful industry application of altimeter-derived currents to quantify variability in Agulhas current impact at particular sites of interest. However they stressed how in situ measurement was critical for reliable quantification of current velocities, even in regions where geostrophic currents are very strong and dominant. In another industry application, Harrington-Missin et al. (2009) explained how altimeter-derived currents can provide valuable quantification of seasonal and interannual trends, complementing deficiencies in relatively short duration in situ measurements.