Cyclonic gyre in the tropical South Atlantic

Gordon, Arnold L.; Bosley, Kathryn Thompson

doi:10.1016/s0198-0149(12)80015-x

Cited by 94 publications

(51 citation statements)

References 28 publications

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“…To the north the sections are used to a few degrees south of the equator, where the flow field becomes complicated and the normal geostrophic equations become quite sensitive to data variations and may even begin to break down. The equatorial region east of the Greenwich Meridian is not included here in the meridional sections since this region is dominated by the cyclonic gyre of the Angola Dome (Moroshkin et al, 1970;Gordon and Bosley, 1991), and because the Benguela Current, as part of the subtropical gyre south of the Angola Dome, was investigated in an earlier study (Stramma and Peterson, 1989). First we performed a quality check on all the station data and removed the obviously incorrect values on the basis of TS-diagrams.…”

Section: The Datamentioning

confidence: 99%

Geostrophic transport of the South Equatorial Current in the Atlantic

Stramma¹

1991

J Mar Res

125

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Geostrophic transport calculations from historical data of the equatorial South Atlantic are presented for the investigation of the flow field in the South Equatorial Current region. On the basis of water mass distribution, the potential density surface of 0', = 32.15 kg m-3 is used as a reference for geostrophic shears. This reference surface is located at a depth of 1000 to 1200 m and represents the boundary between the upper branch of the Circumpolar Deep Water and the Upper North Atlantic Deep Water. The southern band of the South Equatorial Current (SSEC) is fed by the Benguela Current, which crosses the Greenwich Meridian south of 20S. West of the Greenwich Meridian the subtropical gyre has its northernmost current band as the westward flowing SSEC. The SSEC was found to be a broad sluggish flow between lOS and 25S. The transport of the SSEC in the upper 500 m is in the order of 20 Sv, with surface velocities of around 10 cm s-'. At 30W the SSEC turns northward. A small part of the water turns poleward south of lOS to form the Brazil Current, whereas the bulk of the flow contributes to the North Brazil Current and the South Equatorial Countercurrent (SECC). The SECC seems to cross the entire South Atlantic eastward to at least the Greenwich Meridian, but part of the flow might contribute to the middle branch of the South Equatorial Current flowing westward. The northernmost current band sampled is the eastward flowing South Equatorial Undercurrent. From this data no seasonality in the geostrophic field can be proven.

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Section: The Datamentioning

confidence: 99%

Geostrophic transport of the South Equatorial Current in the Atlantic

Stramma¹

1991

J Mar Res

125

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“…Subsequent geostrophic calculations (Defant, 1941) suggested a continuous northward flow along the western boundary from 301S to the equator and beyond, while retaining significant interior northward currents for the region south of 251S. More recently, estimates based on the geostrophic method (Reid, 1989;Gordon and Bosley, 1991;Suga and Talley, 1995;Talley, 1996) replaced this concept of a basin-wide northward flow by a succession of two basin-scale, zonally stretched gyres: the anticyclonic Subtropical Gyre centred at 341S and the cyclonic Tropical Gyre (Gordon and Bosley, 1991) centred at about 10-151S (See Fig. 2).…”

Section: Introductionmentioning

confidence: 99%

Lagrangian circulation of Antarctic Intermediate Water in the subtropical South Atlantic

Núñez‐Riboni

Boebel

Ollitrault

et al. 2005

Deep Sea Research Part II: Topical Studies in Oceanography

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This study combines float data from different projects collected between 1991 and 2003 in the South Atlantic to describe the flow of Antarctic Intermediate Water (AAIW). Velocity space-time averages are calculated for various grid resolutions and with cells deformed to match the bathymetry, f/H or f/h (with H being the water depth and h being the thickness of the AAIW layer). When judged by the degree of alignment between respective isolines and the resulting average velocity fields, the best grid is based on a nominal cell size of 31 (latitude) by 41 (longitude) with cell shapes deformed according to f/h. Using this grid, objectively estimated mean currents (and their associated errors), as well as meridional and zonal volume transports are estimated. Results show an anticyclonic Subtropical Gyre centred near 361S and spanning from 23711S to 46711S. The South Atlantic Current meanders from 331S to 461S and shows a mean speed of 9.677.8 cm s À1 (8.573.5 Sv; 1 Sv ¼ 1 Â 10 6 m 3 s À1 ). The northern branch of the Subtropical Gyre is located between 221S and 321S and flows westward with a mean speed of 4.773.3 cm s À1 (9.373.4 Sv). Evidence of a cyclonic Tropical Gyre divided in two sub-cells is visible on the stream function. r

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“…The format for this diagram is based on a figure layout I first saw in a report by Gordon (1991), although the How patterns shown constitute a substantial modification ofthe original figure. But I would like to emphasize that I feel that Arnold Gordon's contributions to the topics under consideration are both crucial and stimulating.…”

Section: Introductionmentioning

confidence: 99%

On the world ocean circulation. Volume II, the Pacific and Indian Oceans/a global update

Schmitz¹

1996

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Cyclonic gyre in the tropical South Atlantic

Cited by 94 publications

References 28 publications

Geostrophic transport of the South Equatorial Current in the Atlantic

Geostrophic transport of the South Equatorial Current in the Atlantic

Lagrangian circulation of Antarctic Intermediate Water in the subtropical South Atlantic

On the world ocean circulation. Volume II, the Pacific and Indian Oceans/a global update

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