Near-surface currents and hydrology off southern Angola in July 1999.

Autor: Boyd, A.J., Filipe, V.L.L., Bartholomae, C.H.
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Zdroj: South African Journal of Science; May/Jun2001, Vol. 97 Issue 5/6, p219, 4p, 4 Diagrams
Abstrakt: A box grid, elongated in a north-south direction, was covered over three days in July 1999, cutting across the Angola-Benguela Front (twice) in a quasi-synoptic fashion. The offshore leg lay in water more than 1000 m deep, whereas the minimum depth on the coastal leg was 100 m. Near-surface currents were measured both on station and underway using an acoustic Doppler current profiler with real-time differential GPS input, and the results for 30-40 m depth are compared to the tracks of three drifters and underway temperature and salinity measurements, and a contemporary NOAA AVHRR satellite temperature image. The data sources concur mostly regarding the identification of features, and show the southern margin of the front at 16.5-16.8 degrees S on the offshore leg associated with westward flow of 20 cm s[sup -1]. The currents on the inshore leg showed southerly flow up to 50 cm s[sup -1], with an offshore (i.e. westward) component north of 16.7 degrees S, which could contribute to the westward flow measured on the offshore leg. South of 16.8 degrees S, the flow was southerly up to 30 cm s[sup -1], with an onshore component, and drogues in this current beached further south. The results have important implications for the retention and dispersal of biota such as fish larvae in the region. The value of unbroken transect lines across the front is also highlighted, in that the regions of offshore (westward) flow were identified better than on previous larger-scale cruises. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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