Observations of the horizontal separation of the salinity core and the current core in the Atlantic Equatorial Undercurrent

Fahrbach, Eberhard; Meincke, Jens; Sy, Alexander

doi:10.1357/002224086788401648

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…The most conspicuous features on the average section along 23øW (Figure 2) are also found on individual cruises presented in Hisard and Hdnin [1987]. Fahrbach et al [1986] showed the association of the EUC core with a sMinity and oxygen maximum in 1979 data, and discussed the meridional separation between the salinity and current cores. This is also present here, and the off-equatorial salinities are lower with the thermochne maximum values being less at 3-4øN and 2-3øS than between 0 and løS.…”

Section: $1 Zonal Circulationmentioning

confidence: 54%

Isopycnal and diapycnal circulation of the upper equatorial Atlantic Ocean in 1983–1984

Gouriou¹,

Reverdin²

1992

J. Geophys. Res.

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Isopycnal circulation and diapycnal processes in the equatorial Atlantic Ocean are investigated using eight cruises from November 1982 to July 1984. An eastward decrease of the transport of the equatorial undercurrent is observed averaging 18.2 106 m3 s−1 at 35°W to 10.2 106 m3 s−1 at 4°W. There is also a meridional convergence at the undercurrent level and a larger meridional divergence in the surface layer of 15 106 m3 s−1 between 35°W and 4°W. In the eastern equatorial Atlantic, the undercurrent core density as well as the salinity above the undercurrent experience a large seasonal cycle. During the season where the eastern Atlantic thermocline is closest to the surface and surface waters are coldest, the current peaks in denser waters and subsurface salinity maximum are weaker. An analysis of the salinity on isopycnal surfaces indicates that there is significant diapycnal mixing in the upper thermocline. In the eastern Atlantic, the upper thermocline vertical heat diffusivity coefficient scaled over 1° of latitude varies between 3 cm2 s−1 during the upwelling season and nearly 0 early in the year. This seasonal mixing is an important element of undercurrent dynamics. The turbulent heat flux at the base of the surface layer averages 50 W m−2 between 1.5°N and 1.5°S. The surface layer heat budget implies an average oceanic gain of 60 W m−2 between 1.5°N and 1.5°S which could result from exchanges with the atmosphere. The heat flux and fresh water seasonal cycles needed to close the budgets are not realistic, however. The eastern equatorial Atlantic thermocline seasonal upwelling is associated with a large inflow into the surface layer. Over the two years, this flow averaging 11–12 × 106 m3 s−1 originates from the upper thermocline, and diapycnal transports near the core of the undercurrent or below are found to be small. Below the core of the undercurrent, we also find that mixing is not intense: for instance, at σθ = 26.5, in the upper part of the thermostad, vertical heat diffusivity is only 0.6 cm2 s−1 (assuming that mixing takes place over 1° of latitude). The uncertainties on these budgets are however large, and assumptions on the dynamics that were used could not be checked.

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Section: $1 Zonal Circulationmentioning

confidence: 54%

Isopycnal and diapycnal circulation of the upper equatorial Atlantic Ocean in 1983–1984

Gouriou¹,

Reverdin²

1992

J. Geophys. Res.

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“…The EUC is centered around the equator and in the thermocline, and is a relatively stable and quasi-permanent feature in both the Pacific and Atlantic Oceans (Izumo 2005:110;Philander 1980:191). It is a strong, "jet-like subsurface current," the source of which (in the Atlantic) is likely the high-salinity Northern Brazil Coastal Current (Fahrbach et al 1986:763; see also Bonhoure et al 2004). In the Gulf of Guinea it exists just under a westward flowing surface current (the SEC), and just above and north of it is the eastward surface flow of the Guinea Current (Bonhoure et al 2004;Philander 1980:202-203).…”

Section: The Equatorial Undercurrent and The Guinea Countercurrentmentioning

confidence: 99%

Of His Bones are Coral Made: Submerged Cultural Resources, Site Formation Processes, and Multiple Scales of Interpretation in Coastal Ghana

Horlings¹

2012

Azania: Archaeological Research in Africa

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Integrating theoretical and methodological approaches to formation processes across a range of scales from micro-artifact to region and from historical to environmental processes, this work explores the archaeology of the event related to submerged archaeological sites within the Elmina seascape of coastal Ghana. Building on and intersecting with the work of other scholars, this research is a unique approach to the investigation of submerged cultural remains related to historical maritime trade. Remote sensing surveys in 2009 led to the identification of three sites related to maritime trade, adding significantly to the two previously known sites, which include a circa 1650 shipwreck, referred to as the Elmina Wreck, and the remains of an early 18 th century vessel in the Benya Lagoon. Drawing on remote sensing survey data, diver investigations, and the micro-sampling sediment coring technique developed over the course of field research, the historic and physical environment of coastal Elmina is studied as a means of interpreting the unique events surrounding a specific shipwreck, and to relate formation processes across the region to this and other sites. While archaeological evidence is limited, the complex study of formation processes, including the historical contexts of trade and the physical environmental has provided insights into events and practices of trade, destruction and preservation of submerged sites, and has provided a foundation for continued holistic investigation and maritime archaeological studies in the region. The methodological and theoretical approaches to formation processes form a model applicable to maritime research across the globe.

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Upper-level circulation in the South Atlantic Ocean

Peterson

Stramma

1991

Progress in Oceanography

1,008

667

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Abstract-In this paper we present a literature survey of the South Atlantic's climate and its oceanic upper-layer circulation and meridional beat transport. The opening section deals with climate and is focused upon those elements having greatest oceanic relevance, i.e., distributions of atmospheric sea level pressure, the wind fields they produce, and the net surface energy fluxes. The various geostrophic currents comprising the upper-level general circulation are then reviewed in a manner organized around the subtropical gyre, beginning off southern Africa with the Agulhas Current Retroflection and then progressing to the Benguela Current, the equatorial current system and circulation in the Angola Basin, the large-scale variability and interannual warmings at low latitudes, the Brazil Current, the South Atlantic Cmrent, and finally to the Antarctic Circumpolar Current system in which the Falkland (Malvinas) Current is included. A summary of estimates of the meridional heat transport at various latitudes in the South Atlantic ends the survey.

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Observations of the horizontal separation of the salinity core and the current core in the Atlantic Equatorial Undercurrent

Cited by 6 publications

References 8 publications

Isopycnal and diapycnal circulation of the upper equatorial Atlantic Ocean in 1983–1984

Isopycnal and diapycnal circulation of the upper equatorial Atlantic Ocean in 1983–1984

Of His Bones are Coral Made: Submerged Cultural Resources, Site Formation Processes, and Multiple Scales of Interpretation in Coastal Ghana

Upper-level circulation in the South Atlantic Ocean

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