Nonlinear internal waves forced by tides near the critical latitude

Vlasenko, Vasiliy; Stashchuk, Nataliya; Hutter, Kolumban; Sabinin, K. D.

doi:10.1016/s0967-0637(03)00018-9

Cited by 66 publications

(59 citation statements)

References 26 publications

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“…The critical condition also leads to enhanced shear and turbulence (Eriksen, 1985). As the turning latitude where ω = f is approached; however, the non-linear terms become increasingly important and the parameter γ becomes a crude indicator of the potential for internal wave generation (Vlasenko et al, 2003). Poleward of the turning latitude negative background vorticities can effectively reduce the inertial frequency and thereby potentially allow for linear sub-inertial internal waves (Kunze and Toole, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…6a) are also co-located with near-critical slopes. An entirely different generation mechanism is possible when non-linearity is strong, leading to unsteady lee waves at relatively short horizontal length scales (see, e.g., Vlasenko et al, 2003). The STORMTIDE results, however, do not include the effect of such non-linear internal wave generation.…”

Section: Discussionmentioning

confidence: 99%

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Tidal forcing, energetics, and mixing near the Yermak Plateau

2015

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Abstract. The Yermak Plateau (YP), located northwest of Svalbard in Fram Strait, is the final passage for the inflow of warm Atlantic Water into the Arctic Ocean. The region is characterized by the largest barotropic tidal velocities in the Arctic Ocean. Internal response to the tidal flow over this topographic feature locally contributes to mixing that removes heat from the Atlantic Water. Here, we investigate the tidal forcing, barotropic-to-baroclinic energy conversion rates, and dissipation rates in the region using observations of oceanic currents, hydrography, and microstructure collected on the southern flanks of the plateau in summer 2007, together with results from a global high-resolution ocean circulation and tide model simulation. The energetics (depthintegrated conversion rates, baroclinic energy fluxes and dissipation rates) show large spatial variability over the plateau and are dominated by the luni-solar diurnal (K 1 ) and the principal lunar semidiurnal (M 2 ) constituents. The volumeintegrated conversion rate over the region enclosing the topographic feature is approximately 1 GW and accounts for about 50 % of the M 2 and approximately all of the K 1 conversion in a larger domain covering the entire Fram Strait extended to the North Pole. Despite the substantial energy conversion, internal tides are trapped along the topography, implying large local dissipation rates. An approximate local conversion-dissipation balance is found over shallows and also in the deep part of the sloping flanks. The baroclinic energy radiated away from the upper slope is dissipated over the deeper isobaths. From the microstructure observations, we inferred lower and upper bounds on the total dissipation rate of about 0.5 and 1.1 GW, respectively, where about 0.4-0.6 GW can be attributed to the contribution of hot spots of energetic turbulence. The domain-integrated dissipation from the model is close to the upper bound of the observed dissipation, and implies that almost the entire dissipation in the region can be attributed to the dissipation of baroclinic tidal energy.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Tidal forcing, energetics, and mixing near the Yermak Plateau

2015

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“…Linear wave solutions for free internal Poincaré waves are restricted at the critical latitude where ω = f for the respective forcing frequency (Vlasenko et al, 2003). For the M 2 tidal component the critical latitude is φ = 74.5 • .…”

Section: Theorymentioning

confidence: 99%

Tidally induced internal motion in an Arctic fjord

Støylen

Fer

2014

Nonlin. Processes Geophys.

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Abstract. The internal response in a stratified, partially enclosed basin subject to semi-diurnal tidal forcing through a narrow entrance is investigated. The site is located above the critical latitude where linear internal waves of lunar semidiurnal frequency are not permitted to propagate freely. Generation and propagation of tidally induced internal Kelvin waves are studied, for baroclinically sub-and supercritical conditions at the mouth of the fjord, using a non-linear 3-D numerical model in an idealized basin and in Van Mijenfjorden, Svalbard, using a realistic topography. The model results are compared to observations of hydrography and currents made in August 2010. Results from both the model and measurements indicate the presence of internal Kelvin waves, even when conditions at the fjord entrance are supercritical. The entrance of Van Mijenfjorden is split into two sounds. Sensitivity experiments by closing each sound separately reveal that internal Kelvin waves are generated at both sounds. When the conditions are near supercritical, a wave pulse propagates inward from the fjord entrance at the beginning of each inflow phase of the tidal cycle. The leading crest is followed by a series of smaller amplitude waves characterized as non-linear internal solitons. However, higher model resolution is needed to accurately describe the influence of small-scale mixing and processes near the sill crest in establishing the evolution of the flow and internal response in the fjord.

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“…In recent years, activities of semi-diurnal internal tides have been observed above the critical latitude (Pisarev, 1996;Parsons et al, 1996;Vlasenko et al, 2003), where freely propagating internal waves are not accommodated by the traditional linear theory of baroclinic tides. Factors of nonlinearity and convection are regarded as the principle reasons for this limitation (Nakamura et al, 2000;Nakamura and Awaji, 2001;Vlasenko et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Factors of nonlinearity and convection are regarded as the principle reasons for this limitation (Nakamura et al, 2000;Nakamura and Awaji, 2001;Vlasenko et al, 2003). Besides, another reason that lies in the inclusion of the horizontal component of the earth's rotation ('non-traditional' term) seems more convincing (Fan and Singh, 2008).…”

Section: Introductionmentioning

confidence: 99%

Spatial structure of internal tidal waves generated on weak topographies

Ping¹,

Singh²

2010

Dynamics of Atmospheres and Oceans

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a b s t r a c tThe generation of internal gravity waves by barotropic tidal flow passing over a two-dimensional topography is investigated. Rather than calculating the conversion of tidal energy, this study focuses on delineating the geometric characteristics of the spatial structure of the resulting internal wave fields (i.e., the configurations of the internal beams and their horizontal projections) which have usually been ignored. It is found that the various possible wave types can be demarcated by three characteristic frequencies: the tidal frequency, ω 0 ; the buoyancy frequency, N; and the vertical component of the Coriolis vector or earth's rotation, f. When different possibilities arising from the sequence of these frequencies are considered, there occur 12 kinds of wave structures in the full 3D space in contrast to the 5 kinds identified by the 2D theory. The constant wave phase lines may form as ellipses or hyperbolic lines on the horizontal plane, provided the buoyancy frequency is greater or less than the tidal frequency. The effect that stems from the consideration of the basic flow is also found, which not only serves as the reason for the occurrence of higher harmonics but also increases the wave strength in the direction of basic flow.

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Nonlinear internal waves forced by tides near the critical latitude

Abstract: Nonlinear internal waves forced by tides near the critical latitude. , , .

Cited by 66 publications

References 26 publications

Tidal forcing, energetics, and mixing near the Yermak Plateau

Tidal forcing, energetics, and mixing near the Yermak Plateau

Tidally induced internal motion in an Arctic fjord

Spatial structure of internal tidal waves generated on weak topographies

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