On the Deep Western Boundary Current Separation and Anticyclone Genesis off Northeast Brazil

Vilela-Silva, Felipe; Silveira, Ilson Carlos Almeida da; Napolitano, Dante Campagnoli; Souza-Neto, Pedro W. M.; Biló, Tiago Carrilho; Gangopadhyay, Avijit

doi:10.1029/2022jc019168

Cited by 3 publications

(3 citation statements)

References 54 publications

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“…As an example of the benefits of compositing, Vilela‐Silva et al. (2023) diagnosed mechanisms of anticyclone formation in the deep Southwest Atlantic by evaluating composites of anticyclone formation at the level of the Deep Western Boundary Current off Northeast Brazil.…”

Section: Model Output and Methodsmentioning

confidence: 99%

“…We extract the signal of the standing meander by reducing the noise from higher-frequency variability (e.g., mesoscale eddies) through smoothing and compositing. As an example of the benefits of compositing, Vilela-Silva et al (2023) diagnosed mechanisms of anticyclone formation in the deep Southwest Atlantic by evaluating composites of anticyclone formation at the level of the Deep Western Boundary Current off Northeast Brazil.…”

Section: Extracting the Standing Signal Of The Meandermentioning

confidence: 99%

“…To investigate the impact of meanders on air‐sea interaction and subduction, we compare composites from periods of low meander curvature (the “relaxed” state) to periods of high meander curvature (the “flexed” state). Composite analyses represent the circulation related to a physical state while reducing noise from motions in other frequencies (e.g., Vilela‐Silva et al., 2023). Following Thompson and Naveira Garabato (2014), we build an index for meander flexing based on the length of the Polar Front (PF) in a meander.…”

Section: Introductionmentioning

confidence: 99%

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The Impact of an Antarctic Circumpolar Current Meander on Air‐Sea Interaction and Water Subduction

Vilela‐Silva,

Bindoff,

Phillips

et al. 2024

JGR Oceans

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Standing meanders along the Antarctic Circumpolar Current (ACC) have been shown to be regions of elevated eddy variability, meridional heat transport, and vertical exchange. In this study, we investigate the influence of a standing meander south of Australia on air‐sea heat fluxes, upper ocean structure, and subduction in the 1/10° ACCESS‐OM2 ocean‐sea ice model forced by the JRA55 atmospheric reanalysis. We track the model's Subantarctic and Polar Fronts based on their jet and water mass structure, and produce composites of thermodynamical and dynamical properties of the meander in relaxed and flexed states. The standing meander induces trough‐to‐crest variations in surface heat flux, mixed layer depth (MLD), wind stress curl, vertical velocity, and subduction. At the crests, the ocean loses heat and the mixed layer is deeper; at the troughs, the ocean gains heat and the mixed layer is shallower. Wind stress curl, vertical velocity, and subduction change sign on entering and exiting crests and troughs. Vertical velocity due to the curvature of the meander is an order of magnitude larger than Ekman vertical velocity. The poleward excursion of Polar Front meander crests extends subduction to Antarctic Intermediate Water density classes. Finally, flexing of the meander enhances both air‐sea exchange and vertical velocity. The results show that standing meanders of the ACC influence the distribution and magnitude of air‐sea fluxes of heat and momentum and exchange between the surface and interior ocean.

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Section: Model Output and Methodsmentioning

confidence: 99%

Section: Extracting the Standing Signal Of The Meandermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Impact of an Antarctic Circumpolar Current Meander on Air‐Sea Interaction and Water Subduction

Vilela‐Silva,

Bindoff,

Phillips

et al. 2024

JGR Oceans

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South Atlantic meridional overturning circulation and its respective heat and freshwater transports from sustained observations near 34.5°S

Pita,

Goes,

Volkov

et al. 2024

Front. Mar. Sci.

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The Atlantic Meridional Overturning Circulation (AMOC) drives northward Meridional Heat Transport (MHT) and affects climate and weather patterns, regional sea levels, and ecosystems. This study uses a methodology recently applied in 22.5°S to estimate the strength and structure of the AMOC, MHT and freshwater (FWT) transports at 34.5°S since 2005. For this, temperature and salinity profiles from sustained observations were used in conjunction with satellite and reanalysis data under two mapping methodologies: (i) an optimized mapping and (ii) a two-layer feed-forward neural network approach. There is strong agreement between both methods for AMOC, MHT and FWT estimates, thus showing the mapping methodologies are robust. In addition, the AMOC variability estimate is significantly correlated with the monthly SAMBA array data (correlation of 0.41). The mean AMOC transport of 17.0 ± 1.6 Sv, a MHT of 0.6 ± 0.1 PW, and a FWT of -0.02 ± 0.01 Sv are estimated between January 2005 and May 2023 at 34.5°S. The MHT and FWT are analyzed in terms of their horizontal (Hhor and Fhor) and overturning contributions (Hov and Fov), and vertical structures. The MHT is dominated by the overturning contribution (correlation of 0.92), while the FWT is controlled by the overturning contribution driven by the wind via Ekman transport at seasonal timescale, and by horizontal contribution at longer timescales. Both horizontal heat (Hhor) and freshwater (Fhor) components are mostly confined to the upper 500 m, with the geostrophic Fov and Fhor offsetting each other between 50 m and 500 m, and the Ekman Fov in the upper 50 m determining the negative FWT. Finally, the estimated mean Fov of -0.15 Sv agrees with previous estimates that the AMOC exports freshwater in the South Atlantic, and suggests that the AMOC is unstable. Although a long-term trend in the Fov was not detected in the past 20 years, there is a salinification trend (0.05 ± 0.01 PSU/decade) in the upper 300 m near 34.5°S since 2005.

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Mid-Deep Circulation in the Western South China Sea and the Impacts of the Central Depression Belt and Complex Topography

Mai,

Wang,

Chen

et al. 2024

JMSE

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As a key component of meridional overturning circulation, mid-deep circulation plays a crucial role in the vertical and meridional distribution of heat. However, due to a lack of observation data, current knowledge of the dynamics of mid-deep circulation currents moving through basin boundaries and complicated seabed topographies is severely limited. In this study, we combined oceanic observation data, bathymetric data, and numerical modeling of the northwest continental margin of the South China Sea to investigate (i) the main features of mid-deep circulation currents traveling through the central depression belt and (ii) how atmospheric-forcing (winds) mesoscale oceanic processes such as eddies and current–topography interactions modulate the mid-deep circulation patterns. Comprehensive results suggest that the convergence of different water masses and current–topography interactions take primary responsibility for the generation of instability and enhanced mixing within the central depression belt. By contrast, winds and mesoscale eddies have limited influence on the development of local circulation patterns at mid-deep depths (>400 m). This study emphasizes that the intensification and bifurcation of mid-deep circulation; specifically, those induced by a large depression belt morphology determine the local material cycle (temperature, salinity, etc.) and energy distribution. These findings provide insights for a better understanding of mid-deep circulation structures on the western boundary of ocean basins such as the South China Sea.

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On the Deep Western Boundary Current Separation and Anticyclone Genesis off Northeast Brazil

Cited by 3 publications

References 54 publications

The Impact of an Antarctic Circumpolar Current Meander on Air‐Sea Interaction and Water Subduction

The Impact of an Antarctic Circumpolar Current Meander on Air‐Sea Interaction and Water Subduction

South Atlantic meridional overturning circulation and its respective heat and freshwater transports from sustained observations near 34.5°S

Mid-Deep Circulation in the Western South China Sea and the Impacts of the Central Depression Belt and Complex Topography

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