Articles de revues : « Boundary currents »

1

Hogg, Nelson G., and William E. Johns. "Western boundary currents." Reviews of Geophysics 33, S2 (1995): 1311–34. http://dx.doi.org/10.1029/95rg00491.

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2

Ruju, Andrea, Pablo Higuera, Javier L. Lara, Inigo J. Losada, and Giovanni Coco. "RIP CURRENTS ON A BARRED BEACH." Coastal Engineering Proceedings 1, no. 33 (2012): 38. http://dx.doi.org/10.9753/icce.v33.currents.38.

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This work presents the numerical study of rip current circulation on a barred beach. The numerical simulations have been carried out with the IH-FOAM model which is based on the three dimensional Reynolds Averaged Navier-Stokes equations. The new boundary conditions implemented in IH-FOAM have been used, including three dimensional wave generation as well as active wave absorption at the boundary. Applying the specific wave generation boundary conditions, the model is validated to simulate rip circulation on a barred beach. Moreover, this study addresses the identification of the forcing mechanisms and the three dimensional structure of the mean flow.

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Cessi, Paola, and Christopher L. Wolfe. "Adiabatic Eastern Boundary Currents." Journal of Physical Oceanography 43, no. 6 (2013): 1127–49. http://dx.doi.org/10.1175/jpo-d-12-0211.1.

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Abstract The dynamics of the eastern boundary current of a high-resolution, idealized model of oceanic circulation are analyzed and interpreted in terms of residual mean theory. In this framework, it is clear that the eastern boundary current is adiabatic and inviscid. Nevertheless, the time-averaged potential vorticity is not conserved along averaged streamlines because of the divergence of Eliassen–Palm fluxes, associated with buoyancy and momentum eddy fluxes. In particular, eddy fluxes of buoyancy completely cancel the mean downwelling or upwelling, so that there is no net diapycnal residual transport. The eddy momentum flux acts like a drag on the mean velocity, opposing the acceleration from the eddy buoyancy flux: in the potential vorticity budget this results in a balance between the divergences of eddy relative vorticity and buoyancy fluxes, which leads to a baroclinic eastern boundary current whose horizontal scale is the Rossby deformation radius and whose vertical extent depends on the eddy buoyancy transport, the Coriolis parameter, and the mean surface buoyancy distribution.

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Ozdemir, Celalettin Emre, and Sahar Haddadian. "SEDIMENT TRANSPORT DUE TO CURRENT-SUPPORTED TURBIDITY CURRENTS OVER AN ERODIBLE BED." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 33. http://dx.doi.org/10.9753/icce.v36.currents.33.

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Wave- and current-supported turbidity currents (WCSTCs), are one of the chief participants in shaping the marine geomorphology. What makes WCSTCs different from other turbidity currents is that boundary layer turbulence is required to suspend the sediments rather than the self-motion of the turbidity currents. In the presence of a mild slope, the gravitational acceleration drives the suspended sediments offshore (Sternberg et al., 1996; Wright et al., 2001). Depending on what dominates the boundary layer turbulence (BLT), we further define two major subclasses of WCSTCs: (i) wave-supported (WSTCs), and (ii) current-supported turbidity currents (CSTCs). Although significant advances have been made on the details of WSTCs (Ozdemir et al., 2011; Yu et al., 2014; Cheng et al., 2015), less is known about CSTCs. The objective of present study is to investigate the role of alongshore currents on CSTC dynamics over an erodible bottom boundary. The focus here is to identify the possible role of erosion on CSTC dynamics, and assess the coupling between current-induced BLT and suspended sediments for various bed erodibility parameters, i.e. critical shear stress, erosion coefficient, and settling velocity.

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Capodicasa, Erminia, Pietro Scandura, and Foti Enrico. "STEADY CURRENTS INDUCED BY SEA WAVES PROPAGATING OVER A SLOPING BOTTOM." Coastal Engineering Proceedings 1, no. 32 (2011): 35. http://dx.doi.org/10.9753/icce.v32.currents.35.

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A numerical model aimed at computing the mean velocity generated by a sea wave propagating over a sloping bottom, offshore the breaker line, is presented. The model is based on the assumption that the fluid domain can be partitioned into two boundary layers and a core region where at a first order of approximation the flow can be regarded as irrotational. The irrotational flow is computed by using a theory based on the assumption of small amplitude waves which allows both fully absorbed waves and partially reflected waves at the coastline to be considered. The distribution of the mean velocity is controlled by the ratio between the thickness of the boundary layer and the wave amplitude. When this ratio is small, the mean velocities are rather constant along the depth and a second boundary layer develops close to the bottom. In the case of fully reflected waves such boundary layer separates and the mean vorticity can be convected far from the bottom.

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6

Sana, Ahmad, and Hitoshi Tanaka. "NUMERICAL MODELING OF A TURBULENT BOTTOM BOUNDARY LAYER UNDER SOLITARY WAVES ON A SMOOTH SURFACE." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 26. http://dx.doi.org/10.9753/icce.v36.currents.26.

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A number of studies on bottom boundary layers under sinusoidal and cnoidal waves were carried out in the past owing to the role of bottom shear stress on coastal sediment movement. In recent years, the bottom boundary layers under long waves have attracted considerable attention due to the occurrence of huge tsunamis and corresponding sediment movement. In the present study two-equation turbulent models proposed by Menter(1994) have been applied to a bottom boundary layer under solitary waves. A comparison has been made for cross-stream velocity profile and other turbulence properties in x-direction.

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7

Cember, Richard P. "On deep western boundary currents." Journal of Geophysical Research: Oceans 103, no. C3 (1998): 5397–417. http://dx.doi.org/10.1029/97jc02422.

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8

Csanady, G. T., and J. L. Pelegri. "Vorticity balance of boundary currents." Journal of Marine Research 53, no. 2 (1995): 171–87. http://dx.doi.org/10.1357/0022240953213269.

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9

Adityawan, Mohammad Bagus, Hitoshi Tanaka, and Pengzhi Lin. "BED STRESS INVESTIGATION UNDER BREAKING SOLITARY WAVE RUNUP." Coastal Engineering Proceedings 1, no. 33 (2012): 23. http://dx.doi.org/10.9753/icce.v33.currents.23.

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The bed stress under breaking solitary wave runup was investigated in this study using the Simultaneous Coupling Method (SCM). The SCM couples the shallow water equation (SWE) with k-w model. The depth averaged velocity from SWE is applied as the upper boundary condition in k-w model for bed stress assessment from the boundary layer. It was found that the boundary layer approach provides more accurate bed stress estimation than the empirical method, which leads to a more accurate prediction of runup and wave profile. The accumulation of bed stress in during solitary wave runup was evaluated. The bed stress on the direction leaving the shoreline will have more impact in the overall process. However, during a short period of run up process, bed stress toward the shoreline may have significant effect as well.

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10

Ma, Peifeng, and Ole Secher Madsen. "AN OPEN BOUNDARY CONDITION FOR APPLICATION IN NUMERICAL COASTAL MODELS." Coastal Engineering Proceedings 1, no. 32 (2011): 30. http://dx.doi.org/10.9753/icce.v32.currents.30.

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Open boundaries (OBs) are usually unavoidable in numerical coastal circulation simulations. At OBs, appropriate open boundary conditions (OBCs) are required and a good OBC should be able to let outgoing waves freely pass to the exterior of a computational domain without creating reflections at the OBs. In the present study, a methodology has been developed to predict two parameters, phase speed c_r and decay time T_f, in a standard OBC formulation, so that the OBC is significantly improved compared to commonly used existing OBCs with specified c_r and T_f. For the conditions where wave period is unknown, the OBC with approximated c_r and T_f may be applied and a test reveals that this OBC is able to yield good results in typical coastal flow conditions. In addition, a Swing-Door Boundary Condition (SDBC) is proposed and tested for application at an offshore open boundary where both incoming and outgoing waves exist.

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11

Larsen, Bjarke Eltard, and David R. Fuhrman. "RUN-UP, BOUNDARY LAYERS AND SHEAR STRESSES BENEATH SHOALING TSUNAMIS." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 24. http://dx.doi.org/10.9753/icce.v36.currents.24.

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While the tsunami propagation, run-up and inundation has received considerable attention in literature, the associated boundary layer dynamics and induced sediment transport have received relatively little attention. Recently, Williams and Fuhrman (2016) simulated a series of tsunami scale boundary layers, emphasizing that they are simultaneously both current- and wave-like due to their long duration yet unsteady nature. They viewed the tsunami as a time varying current, something that has also been done by Larsen et al. (2017) and Larsen et al. (2018) in studies of tsunami-induced scour around monopile foundations. This approach is valid sufficiently far off-shore, but nearshore, the effects of the free-surface will inevitably become important. While difficult due to the large scales involved, the run-up and inundation can likewise be studied experimentally (Sriram et al. 2016). In this work the run-up process of full-scale tsunamis will be simulated in detail using CFD, which can naturally resolve shorter dispersive waves, wave breaking and boundary layer dynamics.

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12

Hristova, Hristina G., Joseph Pedlosky, and Michael A. Spall. "Radiating Instability of a Meridional Boundary Current." Journal of Physical Oceanography 38, no. 10 (2008): 2294–307. http://dx.doi.org/10.1175/2008jpo3853.1.

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Abstract A linear stability analysis of a meridional boundary current on the beta plane is presented. The boundary current is idealized as a constant-speed meridional jet adjacent to a semi-infinite motionless far field. The far-field region can be situated either on the eastern or the western side of the jet, representing a western or an eastern boundary current, respectively. It is found that when unstable, the meridional boundary current generates temporally growing propagating waves that transport energy away from the locally unstable region toward the neutral far field. This is the so-called radiating instability and is found in both barotropic and two-layer baroclinic configurations. A second but important conclusion concerns the differences in the stability properties of eastern and western boundary currents. An eastern boundary current supports a greater number of radiating modes over a wider range of meridional wavenumbers. It generates waves with amplitude envelopes that decay slowly with distance from the current. The radiating waves tend to have an asymmetrical horizontal structure—they are much longer in the zonal direction than in the meridional, a consequence of which is that unstable eastern boundary currents, unlike western boundary currents, have the potential to act as a source of zonal jets for the interior of the ocean.

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13

Bresch, Didier, and Jacques Simon. "Western boundary currents versus vanishing depth." Discrete & Continuous Dynamical Systems - B 3, no. 3 (2003): 469–77. http://dx.doi.org/10.3934/dcdsb.2003.3.469.

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14

Pelegrí, J. L., and G. T. Csanady. "Diapycnal mixing in western boundary currents." Journal of Geophysical Research 99, no. C9 (1994): 18275. http://dx.doi.org/10.1029/94jc01201.

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15

Spall, Michael A. "Buoyancy-Forced Downwelling in Boundary Currents." Journal of Physical Oceanography 38, no. 12 (2008): 2704–21. http://dx.doi.org/10.1175/2008jpo3993.1.

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Abstract The issue of downwelling resulting from surface buoyancy loss in boundary currents is addressed using a high-resolution, nonhydrostatic numerical model. It is shown that the net downwelling is determined by the change in the mixed layer density along the boundary. For configurations in which the density on the boundary increases in the direction of Kelvin wave propagation, there is a net downwelling within the domain. For cases in which the density decreases in the direction of Kelvin wave propagation, cooling results in a net upwelling within the domain. Symmetric instability within the mixed layer drives an overturning cell in the interior, but it does not contribute to the net vertical motion. The net downwelling is determined by the geostrophic flow toward the boundary and is carried downward in a very narrow boundary layer of width E1/3, where E is the Ekman number. For the calculations here, this boundary layer is O(100 m) wide. A simple model of the mixed layer temperature that balances horizontal advection with surface cooling is used to predict the net downwelling and its dependence on external parameters. This model shows that the net sinking rate within the domain depends not only on the amount of heat loss at the surface but also on the Coriolis parameter, the mixed layer depth (or underlying stratification), and the horizontal velocity. These results indicate that if one is to correctly represent the buoyancy-forced downwelling in general circulation models, then it is crucial to accurately represent the velocity and mixed layer depth very close to the boundary. These results also imply that processes that lead to weak mixing within a few kilometers of the boundary, such as ice formation or freshwater runoff, can severely limit the downwelling forced by surface cooling, even if there is strong heat loss and convection farther offshore.

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16

Pierini, Stefano. "Wind-Driven Fluctuating Western Boundary Currents." Journal of Physical Oceanography 28, no. 11 (1998): 2185–98. http://dx.doi.org/10.1175/1520-0485(1998)028<2185:wdfwbc>2.0.co;2.

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17

da Silveira, Ilson C. A., Glenn R. Flierl, and Wendell S. Brown. "Dynamics of Separating Western Boundary Currents." Journal of Physical Oceanography 29, no. 2 (1999): 119–44. http://dx.doi.org/10.1175/1520-0485(1999)029<0119:doswbc>2.0.co;2.

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18

Lee, Sang-Ki, J. L. Pelegrí, and John Kroll. "Slope Control in Western Boundary Currents." Journal of Physical Oceanography 31, no. 11 (2001): 3349–60. http://dx.doi.org/10.1175/1520-0485(2001)031<3349:sciwbc>2.0.co;2.

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19

Capet, Xavier J., and Xavier J. Carton. "Nonlinear Regimes of Baroclinic Boundary Currents." Journal of Physical Oceanography 34, no. 6 (2004): 1400–1409. http://dx.doi.org/10.1175/1520-0485(2004)034<1400:nrobbc>2.0.co;2.

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20

Cessi, Paola. "Recirculation and separation of boundary currents." Journal of Marine Research 48, no. 1 (1990): 1–35. http://dx.doi.org/10.1357/002224090784984597.

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21

Cessi, Paola, R. Vance Condie, and W. R. Young. "Dissipative dynamics of western boundary currents." Journal of Marine Research 48, no. 4 (1990): 677–700. http://dx.doi.org/10.1357/002224090784988719.

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22

MacCready, Parker. "Frictional decay of abyssal boundary currents." Journal of Marine Research 52, no. 2 (1994): 197–217. http://dx.doi.org/10.1357/0022240943077073.

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23

Thomas, A. C., M. E. Carr, and P. T. Strub. "Chlorophyll variability in eastern boundary currents." Geophysical Research Letters 28, no. 18 (2001): 3421–24. http://dx.doi.org/10.1029/2001gl013368.

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24

Pierini, S. "Stable equivalent-barotropic oceanic boundary currents." Il Nuovo Cimento C 10, no. 3 (1987): 323–35. http://dx.doi.org/10.1007/bf02524831.

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25

Agra, Cigdem, and Doron Nof. "Collision and separation of boundary currents." Deep Sea Research Part I: Oceanographic Research Papers 40, no. 11-12 (1993): 2259–82. http://dx.doi.org/10.1016/0967-0637(93)90103-a.

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26

Cessi, Paola, and Glenn R. Ierley. "Nonlinear Disturbances of Western Boundary Currents." Journal of Physical Oceanography 23, no. 8 (1993): 1727–35. http://dx.doi.org/10.1175/1520-0485(1993)023<1727:ndowbc>2.0.co;2.

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27

Seager, Richard, and Isla R. Simpson. "Western boundary currents and climate change." Journal of Geophysical Research: Oceans 121, no. 9 (2016): 7212–14. http://dx.doi.org/10.1002/2016jc012156.

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Kuehl, Joseph J., and V. A. Sheremet. "Two-layer gap-leaping oceanic boundary currents: experimental investigation." Journal of Fluid Mechanics 740 (January 10, 2014): 97–113. http://dx.doi.org/10.1017/jfm.2013.645.

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AbstractThe problem of oceanic gap-traversing boundary currents, such as the Kuroshio current crossing the Luzon Strait or the Gulf Stream traversing the mouth of the Gulf of Mexico, is considered. Systems such as these are known to admit two dominant states: leaping across the gap or penetrating into the gap forming a loop current. Which state the system will assume and when transitions between states will occur are open problems. Sheremet (J. Phys. Oceanogr., vol. 31, 2001, pp. 1247–1259) proposed, based on idealized barotropic numerical results, that variation in the current’s inertia is responsible for these transitions and that the system admits multiple states. Generalized versions of these results have been confirmed by barotropic rotating-table experiments (Sheremet & Kuehl, J. Phys. Oceanogr., vol. 37, 2007, 1488–1495; Kuehl & Sheremet,J. Mar. Res., vol. 67, 2009, pp. 25–42). However, the typical structure of oceanic boundary currents, such as the Gulf Stream or Kuroshio, consists of an upper-layer intensified flow riding atop a weakly circulating lower layer. To more accurately address this oceanic situation, the present work extends the above findings by considering two-layer rotating table experiments. The flow is driven by pumping water through sponges and vertical seals, creating a Sverdrup interior circulation in the upper layer which impinges on a ridge where a boundary current is formed. The $\beta $ effect is incorporated in both layers by a sloping rigid lid as well as a sloping bottom and the flow is visualized with the particle image velocimetry method. The experimental set-up is found to produce boundary currents consistent with theory. The existence of multiple states and hysteresis, characterized by a cusp topology of solutions, is found to be robust to stratification and various properties of the two-layer system are explored.

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von Dassow, George, Richard Emlet, and Daniel Grünbaum. "Boundary effects on currents around ciliated larvae." Nature Physics 13, no. 6 (2017): 520–21. http://dx.doi.org/10.1038/nphys4154.

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Hilgenkamp, H., C. W. Schneider, B. Goetz, et al. "Grain boundary critical currents - a new perspective." Superconductor Science and Technology 12, no. 12 (1999): 1043–45. http://dx.doi.org/10.1088/0953-2048/12/12/301.

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Bane, John M., Ruoying He, Michael Muglia, Caroline F. Lowcher, Yanlin Gong, and Sara M. Haines. "Marine Hydrokinetic Energy from Western Boundary Currents." Annual Review of Marine Science 9, no. 1 (2017): 105–23. http://dx.doi.org/10.1146/annurev-marine-010816-060423.

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Cessi, Paola. "Laminar separation of colliding western boundary currents." Journal of Marine Research 49, no. 4 (1991): 697–717. http://dx.doi.org/10.1357/002224091784995738.

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Jacobs, Pieter, Yakun Guo, and Peter A. Davies. "Boundary currents over shelf and slope topography." Journal of Marine Systems 19, no. 1-3 (1999): 137–58. http://dx.doi.org/10.1016/s0924-7963(98)00056-6.

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34

Hughes, Roger L. "A frictional sublayer for western boundary currents." Dynamics of Atmospheres and Oceans 17, no. 4 (1993): 243–56. http://dx.doi.org/10.1016/0377-0265(93)90023-z.

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35

Bernatzki, Felicia. "Mass-minimizing currents with an elastic boundary." Manuscripta Mathematica 93, no. 1 (1997): 1–20. http://dx.doi.org/10.1007/bf02677453.

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Waugh, Darryn W., and Timothy M. Hall. "Propagation of Tracer Signals in Boundary Currents." Journal of Physical Oceanography 35, no. 9 (2005): 1538–52. http://dx.doi.org/10.1175/jpo2779.1.

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Abstract The propagation of a range of tracer signals in a simple model of the deep western boundary current is examined. Analytical expressions are derived in certain limits for the transit-time distributions and the propagation times (tracer ages) of tracers with exponentially growing or periodic concentration histories at the boundary current’s origin. If mixing between the boundary current and the surrounding ocean is either very slow or very rapid, then all tracer signals propagate at the same rate. In contrast, for intermediate mixing rates tracer ages generally depend on the history of the tracer variations at the origin and range from the advective time along the current to the much larger mean age. Close agreement of the model with chlorofluorocarbon (CFC) and tritium observations in the North Atlantic deep western boundary current (DWBC) is obtained when the model is in the intermediate mixing regime, with current speed around 5 cm s−1 and mixing time scale around 1 yr. In this regime anomalies in temperature and salinity of decadal or shorter period will propagate downstream at roughly the current speed, which is much faster than the spreading rate inferred from CFC or tritium–helium ages (approximately 5 cm s−1 as compared with 2 cm s−1). This rapid propagation of anomalies is consistent with observations in the subpolar DWBC, but is at odds with inferences from measurements in the tropical DWBC. This suggests that observed tropical temperature and salinity anomalies are not simply propagated signals from the north. The sensitivity of the tracer spreading rates to tracer and mixing time scales in the model suggests that tight constraints on the flow and transport in real DWBCs may be obtained from simultaneous measurements of several different tracers—in particular, hydrographic anomalies and steadily increasing transient tracers.

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Mamchuk, Vitalii, and Leonid Romaniuk. "Calculation of some turbulent wall currents." Scientific journal of the Ternopil national technical university 1, no. 101 (2021): 89–93. http://dx.doi.org/10.33108/visnyk_tntu2021.01.089.

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A mathematical model for the calculation of turbulent boundary layers and wall stream has been developed. The results of calculations are compared with the results of other authors on the compliance of the calculated values with the experimental data. The currents that are formed under the influence of positive pressure gradients and lead to the phenomenon of separation of the turbulent boundary layer are studied.

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BALACHANDRAN, A. P., S. VAIDYA, G. BIMONTE, T. R. GOVINDARAJAN, K. S. GUPTA, and V. JOHN. "CURRENT OSCILLATIONS, INTERACTING HALL DISCS AND BOUNDARY CFTs." International Journal of Modern Physics A 14, no. 07 (1999): 1061–85. http://dx.doi.org/10.1142/s0217751x99000531.

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In this paper, we discuss the behavior of conformal field theories interacting at a single point. The edge states of the quantum Hall effect (QHE) system give rise to a particular representation of a chiral Kac–Moody current algebra. We show that in the case of QHE systems interacting at one point we obtain a "twisted" representation of the current algebra. The condition for stationarity of currents is the same as the classical Kirchoff's law applied to the currents at the interaction point. We find that in the case of two discs touching at one point, since the currents are chiral, they are not stationary and one obtains current oscillations between the two discs. We determine the frequency of these oscillations in terms of an effective parameter characterizing the interaction. The chiral conformal field theories can be represented in terms of bosonic Lagrangians with a boundary interaction. We discuss how these one-point interactions can be represented as boundary conditions on fields, and how the requirement of chirality leads to restrictions on the interactions described by these Lagrangians. By gauging these models we find that the theory is naturally coupled to a Chern–Simons gauge theory in 2+1 dimensions, and this coupling is completely determined by the requirement of anomaly cancellation.

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D'Hieres, G. Chabert, H. Didelle, and D. Obaton. "A laboratory study of surface boundary currents: Application to the Algerian Current." Journal of Geophysical Research 96, no. C7 (1991): 12539. http://dx.doi.org/10.1029/91jc00998.

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Matano, Ricardo P., and Elbio D. Palma. "On the Upwelling of Downwelling Currents." Journal of Physical Oceanography 38, no. 11 (2008): 2482–500. http://dx.doi.org/10.1175/2008jpo3783.1.

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Abstract The term “downwelling currents” refers to currents with a downslope mass flux in the bottom boundary layer. Examples are the Malvinas and Southland Currents in the Southern Hemisphere and the Oyashio in the Northern Hemisphere. Although many of these currents generate the same type of highly productive ecosystems that is associated with upwelling regimes, the mechanism that may drive such upwelling remains unclear. In this article, it is postulated that the interaction between a downwelling current and the continental slope generates shelfbreak upwelling. The proposed mechanism is relatively simple. As a downwelling current flows along the continental slope, bottom friction and lateral diffusion spread it onto the neighboring shelf, thus generating along-shelf pressure gradients and a cross-shelf circulation pattern that leads to shelfbreak upwelling. At difference with previous studies of shelfbreak dynamics (e.g., Gawarkiewicz and Chapman, Chapman and Lentz, and Pickart), the shelfbreak upwelling in the proposed model is not controlled by the downslope buoyancy flux associated with the presence of a shelf current but by the along-shelf pressure gradient associated with the presence of a slope current. As these experiments demonstrate, shelfbreak upwelling will occur in flat-bottomed domains or even in the absence of a bottom boundary layer. The shelfbreak upwelling, moreover, is not evidence of the separation of the bottom boundary layer but of the downstream divergence of the slope currents, and its magnitude is proportional to the volume transport of that current. To prove this hypothesis, the results of a series of process-oriented numerical experiments are presented.

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Higuera, Pablo, Philip L. F. Liu, Cheng Lin, Wei-Ying Wong, and Ming-Jer Kao. "HIGHLY-RESOLVED NUMERICAL AND LABORATORY ANALYSIS FOR NONBREAKING SOLITARY WAVE SWASH OVER A STEEP SLOPE." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 36. http://dx.doi.org/10.9753/icce.v36.currents.36.

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In this paper we study the swash processes generated by a nonbreaking solitary wave running up and down a steep slope (1:3). We use experimental data to study flow features and velocities inside the boundary layer, and numerical modelling to investigate variables not measured during the laboratory experiments, such as pressures and bottom shear stress. We focus on the mechanisms that produce flow separation and vortex formation. Particularly, we study a system of vortices generated under a hydraulic jump during the rundown phase, which was first observed by Matsunaga & Honji (1980).

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Swallow, John, Michèle Fieux, and Friedrich Schott. "The boundary currents east and north of Madagascar: 1. Geostrophic currents and transports." Journal of Geophysical Research 93, no. C5 (1988): 4951. http://dx.doi.org/10.1029/jc093ic05p04951.

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Lazzeretti, Paolo. "Topological definition of ring currents." Physical Chemistry Chemical Physics 18, no. 17 (2016): 11765–71. http://dx.doi.org/10.1039/c5cp06865g.

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A definition of ring currents in a velocity vector field is proposed according to topological criteria: ring currents are axial vortices confined in, or rotating beyond, a separatrix, i.e., the boundary which marks the limits of the vortex.

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Yang, Xiaoting, Eli Tziperman, and Kevin Speer. "Deep Eastern Boundary Currents: Idealized Models and Dynamics." Journal of Physical Oceanography 51, no. 4 (2021): 989–1005. http://dx.doi.org/10.1175/jpo-d-20-0227.1.

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AbstractConcentrated poleward flows along eastern boundaries between 2- and 4-km depth in the southeast Pacific, Atlantic, and Indian Oceans have been observed, and appear in data assimilation products and regional model simulations at sufficiently high horizontal resolution, but their dynamics are still not well understood. We study the local dynamics of these deep eastern boundary currents (DEBCs) using idealized GCM simulations, and we use a conceptual vorticity model for the DEBCs to gain additional insights into the dynamics. Over most of the zonal width of the DEBCs, the vorticity balance is between meridional advection of planetary vorticity and vortex stretching, which is an interior-like vorticity balance. Over a thinner layer very close to the eastern boundary, a balance between vorticity tendencies due to friction and stretching that rapidly decay away from the boundary is found. Over the part of the DEBC that is governed by an interior-like vorticity balance, vertical stretching is driven by both the topography and temperature diffusion, while in the thinner boundary layer, it is driven instead by parameterized horizontal temperature mixing. The topographic driving acts via a cross-isobath flow that leads to stretching and thus to vorticity forcing for the concentrated DEBCs.

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Goldsworth, Fraser W., David P. Marshall, and Helen L. Johnson. "Symmetric Instability in Cross-Equatorial Western Boundary Currents." Journal of Physical Oceanography 51, no. 6 (2021): 2049–67. http://dx.doi.org/10.1175/jpo-d-20-0273.1.

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AbstractThe upper limb of the Atlantic meridional overturning circulation draws waters with negative potential vorticity from the Southern Hemisphere into the Northern Hemisphere. The North Brazil Current is one of the cross-equatorial pathways in which this occurs: upon crossing the equator, fluid parcels must modify their potential vorticity to render them stable to symmetric instability and to merge smoothly with the ocean interior. In this work a linear stability analysis is performed on an idealized western boundary current, dynamically similar to the North Brazil Current, to identify features that are indicative of symmetric instability. Simple two-dimensional numerical models are used to verify the results of the stability analysis. The two-dimensional models and linear stability theory show that symmetric instability in meridional flows does not change when the nontraditional component of the Coriolis force is included, unlike in zonal flows. Idealized three-dimensional numerical models show anticyclonic barotropic eddies being spun off as the western boundary current crosses the equator. These eddies become symmetrically unstable a few degrees north of the equator, and their PV is set to zero through the action of the instability. The instability is found to have a clear fingerprint in the spatial Fourier transform of the vertical kinetic energy. An analysis of the water mass formation rates suggest that symmetric instability has a minimal effect on water mass transformation in the model calculations; however, this may be the result of unresolved dynamics, such as secondary Kelvin–Helmholtz instabilities, which are important in diabatic transformation.

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Hammerl, G., H. Bielefeldt, B. Goetz, et al. "Doping-induced enhancement of grain boundary critical currents." IEEE Transactions on Appiled Superconductivity 11, no. 1 (2001): 2830–37. http://dx.doi.org/10.1109/77.919652.

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Shimada, Koji, and Atsushi Kubokawa. "Nonlinear Evolution of Linearly Unstable Barotropic Boundary Currents." Journal of Physical Oceanography 27, no. 7 (1997): 1326–48. http://dx.doi.org/10.1175/1520-0485(1997)027<1326:neolub>2.0.co;2.

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Spall, Michael A. "Boundary Currents and Watermass Transformation in Marginal Seas*." Journal of Physical Oceanography 34, no. 5 (2004): 1197–213. http://dx.doi.org/10.1175/1520-0485(2004)034<1197:bcawti>2.0.co;2.

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Lee, Sang-Ki. "On the structure of supercritical western boundary currents." Dynamics of Atmospheres and Oceans 33, no. 4 (2001): 303–19. http://dx.doi.org/10.1016/s0377-0265(01)00056-2.

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Stern, Melvin E., and Timour Radko. "Maintaining the inshore shear of continental boundary currents." Dynamics of Atmospheres and Oceans 27, no. 1-4 (1998): 661–78. http://dx.doi.org/10.1016/s0377-0265(97)00037-7.

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