Temporal variations in the separation of Brazil and Malvinas Currents

Olson, Donald B.; Podestá, Guillermo; Evans, Robert H.; Brown, Otis B.

doi:10.1016/0198-0149(88)90120-3

Cited by 337 publications

(266 citation statements)

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“…Another explanation for the occurrence of these species south of its range distribution may be phenomena such as eddies, which can be considered a quasi-stationary structured of Brazilian-Malvinas Confluence (Gordon, 1981). The southern boundary of the Brazilian warm water is accompanied by the intermittent formation of warm core anticyclonic eddies (Gordon, 1981;Olson et al, 1988) and represent a highly complicated system reflected in composition of mesopelagic fish fauna in the surveyed area. The generation of anticyclonic frontal vortices and their further displacement southward leads to the transport of thermophilic forms out of the sub-tropical zone to the sub-Antarctic (Figueroa et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

First report of the black gemfish Nesiarchus nasutus (Perciformes: Gempylidae) in Argentinean waters

et al. 2015

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The gempylid Nesiarchus nasutus is reported for the first time from Argentinean waters, the southernmost occurrence of the species in the Southwestern Atlantic. This suggests that the fluctuating environmental characteristics of the area would be proper for the presence of tropical and subtropical species.Keywords: southwestern Atlantic, Brazilian current, trichiuroids fish, deep-sea. Primeiro relatório do gemfish preto Nesiarchus nasutus (Perciformes: Gempylidae) em águas argentinas ResumoA ocorrência de Nesiarchus nasutus é registrado pela primeira vez em águas argentinas, sendo a esta ocorrência mais meridional da espécie no Atlântico Sudoeste. Isto sugere que as características ambientais flutuantes da área seriam adequadas para a presença de espécies tropicais e subtropicais na mesma. Palavras-chave:Atlântico ocidental sul, corrente do Brasil, trichiuroidea, águas profundas.

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Section: Discussionmentioning

confidence: 99%

First report of the black gemfish Nesiarchus nasutus (Perciformes: Gempylidae) in Argentinean waters

et al. 2015

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“…O modelo fica singular quando da emissão do dipolo e a integração precisa ser interrompida. Tal estrutura bipolar, na primeira camada,é bastante semelhanteàquelas da Confluência Brasil-Malvinas, com o lóbulo anticiclônico, formando anticiclones juntoà margem continental (Olson et al, 1988). O experimento C B M3, portanto, indica que a presença de ondas instáveis que se propagam para oeste levaà formação e emissão de vórtices e dipolos juntos ao contornos, o que não ocorreu para os dois casos anteriores.…”

Section: Experimentos Com Modelo Não-linearunclassified

“…Figura 1 -Imagem AVHRR da confluência Brasil-Malvinas editada a partir de Olson et al (1988). Olson et al (1988).…”

Section: Introductionunclassified

“…Olson et al (1988). Olson et al (1988), valendo-se de observações de derivadores e imagens de satélites, estudaram a variabilidade de mesoescala da Confluência Brasil-Malvinas (Figura 1). Estes autores encontraram que os comprimentos de onda típicos dos meandros observados abrangiam 400 a 500 km e concluíram também que o lóbulo principal de retroflexão da CB frequentemente se alonga para sul e emite grandes grandes vórtices anticiclônicos dentro do giro subpolar.…”

Section: Introductionunclassified

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Estudo teórico da dinâmica da confluência Brasil-Malvinas

Francisco¹,

Silveira²

2004

Rev. Bras. Geof.

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ABSTRACT. The study of the mesoscale dynamics of the confluence of two western boundary currents was conducted in this work via a quasi-geostrophic inviscid f -plane two-layer ocean theoretical approach. The simplified vertical structure was calculated through the employment of a dynamic calibration scheme based on the dynamical mode structure of the Brazil-Malvinas Confluence Region. The Brazil-Malvinas mode structure was computed from climatological hydrography of the area delimited by 35 • -40 • S and 50 • -60 • W. Two contour dynamics models were constructed: a linear and a nonlinear version. The basic flow configuration consisted of two converging western boundary currents that form a zonal eastward current in the upper layer. The lower layer flow was essentially divergent as a result of a westward zonal jet impinging on the western border. This vertical shear choice assured that the system was baroclinically unstable. The results of the model experiments showed that the presence of the confluence, the western meridional boundary and the barotropic mode in the dynamical structure of the basic flow favored long wave patterns. The three experiments conducted with the nonlinear model exhibited the development of both a reflection pattern and vortical dipoles. The dipoles pinched off from either the retroflection lobe (i.e., the primary crest of the wave train) or the primary trough when the baroclinically unstable current system was perturbed at the boundary vicinities.It was verified that the nonlinear model simulations followed the instability properties predicted by the linear model in terms of meander growth rates, phase speeds and most unstable wavelengths. This suggested that while the baroclinic instability mechanism was responsible for the temporal growth of the meanders, the nonlinear effects caused the dipole isolation and pinch off of the finite amplitude meanders. These dipoles could leave and propagate away from the current axis.Keywords: Contour dynamics, calibrated layer models, baroclinic instability, Western Boundary Currents, Brazil-Malvinas Confluence. RESUMO.O estudo da dinâmica de meso-escala da confluência de duas correntes de contorno oeste num oceano de duas camadas quase-geostrófico, não viscoso e inercial no plano f foi conduzido neste trabalho. A estrutura vertical simplificada do modelo foi obtida através de calibração dinâmica em relaçãoà estrutura modal da região da Confluência Brasil-Malvinas. Essa estrutura modal foi estimada a partir da climatologia daárea compreendida entre 35 • -40 • S e 50 • -60 • W. Dois modelos de dinâmica de contornos foram então desenvolvidos. Estes apresentaram sistema de correntes de contorno oeste com transporte simétrico e duas frentes de vorticidade, uma por camada. O escoamento na camada superior foi sempre convergente, formando um jato zonal que flui para leste. Já o escoamento na camada inferior foi divergente, com jato zonal de velocidades fluindo dominantemente para oeste. Tal configuração garantiu que o sistema fosse baroclinicamente instável....

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A two‐way nested simulation of the oceanic circulation in the Southwestern Atlantic

Combes

Matano

2014

JGR Oceans

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This article presents the results of a high-resolution (1/12 ), two-way nested simulation of the oceanic circulation in the southwestern Atlantic region. A comparison between the model results and extant observations indicates that the nested model has skill in reproducing the best-known aspects of the regional circulation, e.g., the volume transport of the ACC, the latitudinal position of the BMC, the shelf break upwelling of Patagonia, and the Zapiola Anticyclone. Sensitivity experiments indicate that the bottom stress parameterization significantly impacts the mean location of the Brazil/Malvinas Confluence and the transport of the Zapiola Anticyclone. The transport of the Brazil Current strengthens during the austral summer and weakens during the austral winter. These variations are driven by the wind stress curl over the southwestern Atlantic. The variations of the transport of the Malvinas Current are out of phase with those of the Brazil Current. Most of the seasonal variability of this current is concentrated in the offshore portion of the jet, the inshore portion has a weak seasonality that modulates the magnitude of the Patagonian shelf break upwelling. Using passive tracers we show that most of the entrainment of deep waters into the shelf occurs in the southernmost portion of the Patagonian shelf and along the inshore boundary of the Brazil Current. Shelf waters are preferentially detrained near the Brazil/Malvinas Confluence. Consistent with previous studies, our simulation also shows that south of $42 S the Malvinas Current is composed of two jets, which merge near 42 S to form a single jet farther north.

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Temporal variations in the separation of Brazil and Malvinas Currents

Cited by 337 publications

References 31 publications

First report of the black gemfish Nesiarchus nasutus (Perciformes: Gempylidae) in Argentinean waters

First report of the black gemfish Nesiarchus nasutus (Perciformes: Gempylidae) in Argentinean waters

Estudo teórico da dinâmica da confluência Brasil-Malvinas

A two‐way nested simulation of the oceanic circulation in the Southwestern Atlantic

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