Interannual variability of South Atlantic circulation from 4 years of TOPEX/POSEIDON satellite altimeter observations

Witter, Donna L.; Gordon, Arnold L.

doi:10.1029/1999jc900023

Cited by 40 publications

(37 citation statements)

References 42 publications

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“…The BMC shows one of the world's largest annual variability in sea surface height signals, in contrast with the ACC (Chelton et al 1990) and, in particular, with the area between ~55 and 48°S, characterised by a local minimum of variability (Fu 1996). Such strong variability has been related to the intense meandering and eddy shedding of this zone (Garzoli & Garraffo 1989, Fu 1996, Witter & Gordon 1999.…”

Section: Introductionmentioning

confidence: 99%

“…The BMC has been the main subject of many research programs focusing on the influence of Atlantic Ocean circulation and sea surface temperature (SST) on the low-frequency changes of the local climate (Goni et al 1996, Boebel et al 1999, Witter & Gordon 1999, Willson & Rees 2000. Previous mesoscale studies on the BMC and adjacent waters have been either focused on environmental factors (Brandini et al 2000) or on microplankton, but restricted temporally (Boltovskoy et al 1996, Fernandes 1999, Thompson et al 1999).…”

Section: Introductionmentioning

confidence: 99%

“…The Subtropical Front (48 to 50°S) represents the northern limit of purely subantarctic waters from the Malvinas Current and the beginning of the Brazil-Malvinas Confluence (BMC) (Peterson & Stramma 1991). In this ample region, subantarctic waters (Malvinas Current), subtropical waters (Brazil Current) and waters of the South Atlantic Drift mix horizontally and vertically, engendering isolated cells and tongues of pure subantarctic or subtropical waters (Witter & Gordon 1999, Willson & Rees 2000. Also, freshwater influence from the Río de la Plata can be detected in the area (Provost et al 1995).…”

Section: Introductionmentioning

confidence: 99%

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Patterns in tintinnid species composition and abundance in relation to hydrological conditions of the southwestern Atlantic during austral spring

Thompson¹,

Alder²

2005

Aquat. Microb. Ecol.

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The tintinnid community was assessed on a collection of 42 samples taken at depths of 5, 10, 25 and 50 m from 17 oceanographic stations located along 34 to 62°S, 51 to 57°W, in November 1995. Samples were collected by means of a Niskin bottle cast, and reverse-filtered through a 10 µm mesh filter. A total of 60 tintinnid taxa were recorded, most of which with a distribution circumscribed to Antarctic, Subantarctic or Brazil-Malvinas Confluence waters, thus allowing the distinction of Antarctic, Subantarctic and Transitional biogeographic zones, respectively. A comparison based on the analysis of Niskin bottle versus flowmetered 35 µm mesh net paired samples indicated that absolute abundances of tintinnid species with diameters > 40 µm almost did not differ between collecting methods. Tintinnid abundances and species structure reflected the degree of variability in the hydrological conditions of the southwestern Atlantic between 1994 and 1995. Sea surface temperature fluctuations within Brazil-Malvinas Confluence waters involved pronounced changes in the tintinnid communities of the Transition Zone: the increase of southward warm water transport during 1994 favoured the dominance of subtropical species along the ecotone, while its decrease during 1995 favoured the contribution of subantarctic species. Low hydrological variability in the Subantarctic and Antarctic Zones was reflected in a quite similar tintinnid community structure during these 2 years. Acanthostomella norvegica forma typica and Cymatocylis antarctica forma typica in the Subantarctic Zone, and Codonellopsis gaussi and Cymatocylis convallaria in the Antarctic Zone, might be regarded as key tintinnid species, based on their persistence and dominance.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Patterns in tintinnid species composition and abundance in relation to hydrological conditions of the southwestern Atlantic during austral spring

Thompson¹,

Alder²

2005

Aquat. Microb. Ecol.

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“…The question here is what causes this interannual variability. Witter and Gordon (1999) found interannual variations from empirical orthogonal functions of TOPEX/POSEIDON sea level observations. Two main modes of variability were identified.…”

Section: Climatology Of the Soda Reanalysismentioning

confidence: 99%

Seasonal and interannual variability of the southern south Equatorial Current bifurcation and meridional transport along the eastern brazilian edge.

Veleda¹,

Araújo²,

Silva³

et al. 2011

TropOcean

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The dynamics of the southern band of the South Equatorial Current (sSEC) near to Brazilian shelf is investigated using recent field observations and a regional numerical modeling approach. The field measurements were obtained from five moorings deployed by German CLIVAR (Climate Variability and Predictability Program) cruises (March 2000-August 2004) along a crossshore line at 11oS. The Regional Ocean Model (ROMS) is used to simulate the circulation and thermohaline structures within the ocean area comprised between 5°S-25°S and 20°W-47°W. This integration domain was covered by an isotropic 1/12o horizontal grid and 40 terrain-following layers. The numerical results confirm a seasonal migration of the sSEC divergence along the Brazilian edge, as well as its depth dependence with a maximum southward shift in July at 200 m depth, while a maximum northward displacement occurs in November at this same depth. This intrannual variability coincides with the North Brazil Undercurrent (NBUC) seasonality at 11oS from moorings measurements. Empirical Orthogonal Function (EOF) and numerical results show a minimum NBUC strength during November and a maximum northward transport in July. The mean transport from field measurements is 25Sv while this from numerical simulations is 24.5Sv. The SODA reanalysis with 47 years of monthly mean indicates that the sSEC has not only a seasonal variability as well as quasi-biannual variability.

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“…In this process, external forcings may induce variability in the South Atlantic boundary currents, which may, in turn, impact the whole of the SASG. Studies of the gyre-scale circulation and of low-frequency variability in the boundary current regimes may, therefore, provide insight to variations of the thermohaline circulation (Witter and Gordon, 1999). …”

Section: Introductionmentioning

confidence: 99%

Changes in the South Atlantic Subtropical Gyre circulation from the 20th into the 21st century

Oliveira¹

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Interannual variability of South Atlantic circulation from 4 years of TOPEX/POSEIDON satellite altimeter observations

Cited by 40 publications

References 42 publications

Patterns in tintinnid species composition and abundance in relation to hydrological conditions of the southwestern Atlantic during austral spring

Patterns in tintinnid species composition and abundance in relation to hydrological conditions of the southwestern Atlantic during austral spring

Seasonal and interannual variability of the southern south Equatorial Current bifurcation and meridional transport along the eastern brazilian edge.

Changes in the South Atlantic Subtropical Gyre circulation from the 20th into the 21st century

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