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Free Content Exploratory observations of abyssal currents in the South Atlantic near Vema Channel

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Abstract:

Vema Channel (nominal location 30S, 40W) is a major passage for the flow of Antarctic Bottom Water on its way northward from the Argentine Basin to the Brazil Basin. New data based on approximately year-long current meter deployments at abyssal depths yield mean or time-averaged kinetic energies as strong as 240 cm2s−2, and eddy kinetic energies from 8 to 40 cm2s−2. We observe a persistent northward flow of AABW with maximum speed near 40 cm s−1, as is found at abyssal depths in the vicinity of the GulfStream. The highest value of mean kinetic energy in Vema Channel (240 cm2 s−2) is much larger than that (∼20 cm2 s−2) found in the flow of Antarctic Bottom Water near the Ceara Rise, and comparable to values of 220 cm2 s−2 for the southward flow of North Atlantic Deep Water on the Blake-Bahama Outer Ridge. Existing observations of mean kinetic energy at locations near the GulfStream System do not exceed 100 cm2 s−2 in the abyssal depth range.

Eddy kinetic energies of 8 cm−2 s−2 are comparable to estimates (at similar depths) from areas at roughly equivalent latitudes, like MODE (Mid-Ocean Dynamics Experiment, nominal location 28N, 70W). However, abyssal kinetic energies as large as 40 cm2 s−2 are normally found only near strong current regimes, in contrast to values of roughly 1 cm2 s−2 in the ocean interior. Values of 18 to 64 cm2 s−2 have been observed near the southward flow of North Atlantic Deep Water on and adjacent to the Blake-Bahama Outer Ridge near 30N, and up to 20 cm2 s−2 in the flow of Antarctic Bottom Water over the Ceara Rise. The strongest abyssal eddy field yet observed, ∼100 to 150 cm2 s−2, occurs near the GulfStream.

Document Type: Research Article

DOI: https://doi.org/10.1357/002224083788519731

Publication date: 1983-08-01

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  • The Journal of Marine Research publishes peer-reviewed research articles covering a broad array of topics in physical, biological and chemical oceanography. Articles that deal with processes, as well as those that report significant observations, are welcome. In the area of biology, studies involving coupling between ecological and physical processes are preferred over those that report systematics. Authors benefit from thorough reviews of their manuscripts, where an attempt is made to maximize clarity. The time between submission and publication is kept to a minimum; there is no page charge.
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