On the baroclinic structure of the Brazil Current–Intermediate Western Boundary Current system at 22°–23°S

Silveira, Ilson Carlos Almeida da; Calado, Leandro; Castro, Belmiro Mendes de; Cirano, Mauro; Lima, José Antônio Moreira; Mascarenhas, A. d. S.

doi:10.1029/2004gl020036

Cited by 138 publications

(158 citation statements)

References 11 publications

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“…1) as confirmed by their high CV's observed (Table I). This pattern has been observed before (13) and it is explained by the local topography interacting with the complex current flow and water mass structures (39). In distribution maps we identified nuclei of biological activity in the area of the reported São Tomé Eddy (23ºS, 40ºW; ref.…”

Section: Discussionsupporting

confidence: 79%

“…4b) where they reached up to 85% of total abundance. The area south 19ºS is characterized by some oceanographic features as eddies and upwelings (13,39,43) that feed the epipelagic zone with cold and nutrient-rich waters remobilized from the bottom. This is the most probable explanation for the high nitrate values reported for station 1 and responsible for the dark spot on distribution map (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Distribution of HNA and LNA bacterial groups in the Southwest Atlantic Ocean

Andrade¹,

Gonzalez²,

Rezende³

et al. 2007

Braz. J. Microbiol.

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Bacterioplankton was studied in a large area of Southwest Atlantic Ocean between 13 and 25ºS and 28 and 42ºW. Samples were collected in 108 stations at 20 m depth. Bacteria were enumerated by flow cytometry after nucleic acid staining with syto13 and two subgroups were differentiated: low nucleic acid content (LNA) and high nucleic acid content (HNA) bacteria. Total bacterial numbers varied from 0.37 to 5.53 10 5 cells mL -1. HNA cells represented 15 to 70% of the total number while LNA cells represented 30 to 85%. Heterotrophic bacterial production was determined by incorporation of tritiated leucine and ranged from 2.7 to 171.07 ng C L -1 h -1. No significant correlation was found between abundance and production. Nevertheless with support of multivariate analysis between bacterial abundance, bacterial production, chlorophyll a and other oceanographic data the distribution of the groups in two different oceanic provinces could be explained by nutrient availability. HNA bacteria accounted for the high percentage of cells found in the area north of 19ºS, linked to higher temperature waters and riverine nutrients inputs. LNA bacteria were the dominant cells south of this latitude and were correlated to the higher values of nitrate found for the same area.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Distribution of HNA and LNA bacterial groups in the Southwest Atlantic Ocean

Andrade¹,

Gonzalez²,

Rezende³

et al. 2007

Braz. J. Microbiol.

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“…Similar deep undercurrents, although not seasonal, are found in other western-boundary-current systems. For instance, in the Brazil Current system, a deep undercurrent is located at 800 m (Da Silveira et al 2004), similar to the undercurrents of the Agulhas (Beal and Bryden 1997;Beal 2009) and East Australian (Mata et al 2000) current systems. In contrast to EBUs, alongshore winds in western-boundary current systems do not generate undercurrents (McCreary and Kundu 1985).…”

Section: Current Vertical Structurementioning

confidence: 99%

Western boundary upwelling dynamics off Oman

et al. 2017

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Despite its climatic and ecosystemic significance, the coastal upwelling that takes place off Oman is not well understood. A primitive-equation, regional model forced by climatological wind stress is used to investigate its dynamics and to compare it with the better-known Eastern Boundary Upwellings (EBUs). The solution compares favorably with existing observations, simulating well the seasonal cycles of thermal structure, surface circulation (mean and turbulent), and sea-surface temperature (SST). There is a 1.5-month lag between the maximum of the upwellingfavorable wind-stress-curl forcing and the oceanic response (minima in sea-surface height and SST), which we attribute to onshore-propagating Rossby waves. A southwestwardflowing undercurrent (opposite to the direction of the nearsurface flow) is also simulated with a core depth of 1000 m, much deeper than found in EBUs (150-200 m). An EKE budget reveals that, in contrast to EBUs, the upwelling jet is more prone to barotropic than baroclinic instability and the contribution of locally-generated instabilities to EKE is higher by an order of magnitude. Advection and redistribution of EKE by standing mesoscale features also play a significant role in EKE budget.

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“…Silveira et al (2000) and Stramma et al (1990) observed it around 10 • S, and Soutelino (2008) The southward transport by the BC from the shore until 39 • W at 22 • S produced by the control run, the assimilation run and the HYCOM+NCODA in December 2009 were 1.3 Sv, 4.1 Sv and 4.8 Sv, respectively. According to Evans & Signorini (1985) and Silveira et al (2004), the BC transport in this region is given by 6 Sv and 5.6 ± 1.4 Sv, respectively. The northward transport by the IWBC in the same region were 7.89 Sv, 4.81 Sv and 1.92 Sv for the control run, the assimilation run and the HYCOM+NCODA, respectively.…”

Section: Resultsmentioning

confidence: 81%

“…The northward transport by the IWBC in the same region were 7.89 Sv, 4.81 Sv and 1.92 Sv for the control run, the assimilation run and the HYCOM+NCODA, respectively. According to Silveira et al (2004) the observed transport by IWBC was 3.6 ± 0.8 Sv. Therefore, the assimilation run produced a positive impact in the currents and transport in this region not only in the surface but also in the subsurface.…”

Section: Resultsmentioning

confidence: 95%

Assimilation of Sea Surface Height Anomalies Into Hycom With an Optimal Interpolation Scheme Over the Atlantic Ocean Metarea V

Tanajura¹,

Costa²,

Silva³

et al. 2013

Braz J Geophys

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ABSTRACT. Along-track sea surface height anomaly (SSHA) data from the Jason-1 and Jason-2 satellites were assimilated into the ocean model HYCOM from July 1, 2009 until December 31, 2009. A new and simple approach to overcome the bias between the model and observed SSHA was proposed. It focuses on the meso-scale differences between the data and the model along each satellite track. An optimal interpolation method and the Cooper & Haines (1996) scheme (C&H) were employed to produce a SSHA analysis field and to adjust model layer thicknesses over the Atlantic METAREA V. The corrected model state was used as initial condition for the next assimilation cycle. SSHA data with a 7-day window were assimilated in 3-day intervals centered in the SSHA data window and the C&H scheme was applied taking the SSHA analysis. A control run without assimilation was also performed. The results showed that the model SSHA was completely reorganized by the end of the experiment. The modifications of SSHA were compared to the American Navy HYCOM+NCODA system and AVISO data. Maximum error was reduced from 0.7 m to 0.2 m by assimilation. Comparisons were also made with the Argo temperature and salinity vertical profiles. Improvements in the currents and volume transport were also produced by assimilation. The impact in temperature was in general positive, but there was no substantial modification in salinity.Keywords: ocean data assimilation, Jason-1 and Jason-2 satellites, Argo. O estado corrigido do modelo foi usado como condição inicial para o próximo ciclo de assimilação. Dados de AASM em uma janela de 7 dias foram assimilados a cada 3 dias em data centrada na janela de dados e o método de C&H foi aplicado com a análise de AASM. Os resultados mostraram que a AASM do modelo foi completamente reorganizada no final do experimento. As modificações de AASM foram comparadas com análises globais do sistema Americano HYCOM+NCODA e com dados do AVISO. Erros máximos foram reduzidos de 0,7 m para 0,2 m com a assimilação. Comparações foram também feitas com perfis verticais de temperatura e salinidade do Argo. Melhorias nas correntes e no transporte de volume foram produzidas em relaçãoà rodada de controle. O impacto na temperatura foi em geral positivo, mas não houve modificação substancial na salinidade. RESUMO.Palavras-chave: assimilação de dados oceanográficos, satélites Jason-1 e Jason-2, Argo.

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On the baroclinic structure of the Brazil Current–Intermediate Western Boundary Current system at 22°–23°S

Cited by 138 publications

References 11 publications

Distribution of HNA and LNA bacterial groups in the Southwest Atlantic Ocean

Distribution of HNA and LNA bacterial groups in the Southwest Atlantic Ocean

Western boundary upwelling dynamics off Oman

Assimilation of Sea Surface Height Anomalies Into Hycom With an Optimal Interpolation Scheme Over the Atlantic Ocean Metarea V

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