Numerical simulation of m2 internal tides in the south brazil bight and their interaction (2008)
- Authors:
- USP affiliated authors: CASTRO FILHO, BELMIRO MENDES DE - IO ; SILVEIRA, ILSON CARLOS ALMEIDA DA - IO
- Unidade: IO
- Assunto: CORRENTES MARINHAS
- Language: Inglês
- Abstract: A fully three-dimensional nonlinear primitive equation ocean model is applied to study the M2 internal tide in the South Brazil Bight (SBC), considering the presence of an anticyclonic eddy in the region. The simulated mean flow is dominated by the warm mesoscale eddy located in the central area of the SBC. The center of this anticyclonic eddy is placed over the 500 m isobath and velocities reach 1.0 m s-1 at the offshore portion of the eddy. High velocities were also modeled close to the 200 m isobath at the NW quadrant. The internal tide activity is concentrated in the region influenced by the eddy and it tends to be more intense outside of the vortex core. The greatest tidal baroclinic velocities (0.2 m s-1) are found at the offshore side of the eddy between 1000 and 1500 m isobaths. The relationship between topographic slope and internal wave characteristics indicates that internal tides would be generated between 500 and 1500 m isobaths, with offshore propagation as the modeled results have showed. However, this relationship could not explain the intensification of internal tide currents modeled offshore in the region where the eddy is located. The vorticity associated with the presence of the eddy modifies the frequency band where free propagation of internal waves is possible from f<w<N (where f is the Coriolis frequency, w the internal wave frequency and N the buoyancy frequency) to feff<w<N where feff(x,y,t) = f + vort(x,y,t) e vort(x,y,t) =(dV/dx)-(dU/dy). Such a shift creates waveguide conditions in the region of negative relative vorticity that may lead to the trapping of near-inertial waves. These trapped internal waves may be advected by the subinertial flow where amplification may occur. Although the modeled eddy has positive relative vorticity, it is surrounded by vorticity of opposite sign that during some periods, can shift feff to values greater or closer to w (w=1.40518x10-4 s-1 in the case of M2) close to the 200 m isobath and offshore of the 1000 m isobath. Thus, the results indicate that the vorticity associated with the presence of the eddy has an important influence upon the propagation of these internal tides, trapping and enhancing them in regions of negative vorticity. The numerical results demonstrate the strong dependence of the internal tide structure of the background conditions and density field. They also indicate that model comparisons with observations have to attempt to the hydrographical and hydrodynamic conditions of the region during the observation period, especially, in areas with strong baroclinic flows. In a Eulerian frame of reference, the varying background conditions will alter the path of the internal tide. Measurements at a fixed location may simply miss the internal tide signal from time to time, or more fundamentally, the variation in the stratification varies in position with respect to the slope to the extent that it only periodically allows thegeneration of an internal tide
- Imprenta:
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ABNT
CASTRO, Belmiro Mendes de e CALAFO, Leandro e SILVEIRA, Ilson Carlos Almeida da. Numerical simulation of m2 internal tides in the south brazil bight and their interaction. 2008, Anais.. São Paulo: Iousp, 2008. . Acesso em: 31 dez. 2025. -
APA
Castro, B. M. de, Calafo, L., & Silveira, I. C. A. da. (2008). Numerical simulation of m2 internal tides in the south brazil bight and their interaction. In . São Paulo: Iousp. -
NLM
Castro BM de, Calafo L, Silveira ICA da. Numerical simulation of m2 internal tides in the south brazil bight and their interaction. 2008 ;[citado 2025 dez. 31 ] -
Vancouver
Castro BM de, Calafo L, Silveira ICA da. Numerical simulation of m2 internal tides in the south brazil bight and their interaction. 2008 ;[citado 2025 dez. 31 ] - On the baroclinic structure of the Brazil current-intermediate western boundary current system at 22°-23°S
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