Browsing by Author "Durgadoo, J V"

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    Ocean currents south of Africa from drifters
    (2008) Durgadoo, J V; Ansorge, I J; Lutjeharms, J R E
    The ocean currents and their variability south of Africa are known to cover a wide spectrum, spatially and possibly temporally. Hydrographic observations in this vast ocean region are logistically demanding and expensive. In recent years the prevalence of drifting buoys has allowed one to infer certain current characteristics for the region that otherwise would be difficult. Observations from satellite-tracked drifters drogued at a depth of 15 m, collected between 1988 and 2005, were used to infer the mean surface circulation and kinetic energy distributions of the surface flow in the African sector of the Southern Ocean between 30 and 60°S. Regions of intensified flow and of higher levels of eddy kinetic energy were identified and agree fairly well with those established from remote sensing products. These results confirm the value of these observations and indicate the increasing usefulness of this data set as the number of drifter tracks increases.
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    The first oceanographic survey of the Conrad Rise
    (2008) Ansorge, I J; Roman, R; Durgadoo, J V; Ryan, P G; Dlamini, L; Gebhardt, Z; Rainier, S; Smith, M; Mtonsti, T; Lutjeharmsa, J R E
    This article presents data collected during the first hydrographic survey of the Conrad Rise, South-West Indian Ocean. Past investigations have shown that the Conrad Rise acts as an obstacle to the flow of the Antarctic Circumpolar Current (ACC). Numerical modelled data suggest that two eastward-flowing jets are formed on the northern and southern extremities of the rise as a result of the bifurcation of the ACC. Hydrographic data collected during the research cruise corroborate the model findings and provide a wealth of empirical data for further investigation of this dynamic ocean region. Counts of seabirds conducted during the cruise revealed unusually large numbers of penguins and diving petrels associated with the frontal jets, suggesting that the area is important for the large populations of penguins breeding at the Prince Edward and Crozet islands farther north.