Internal seiche dynamics in Lake Geneva

Lemmin, Ulrich; Mortimer, C. H.; Bäuerle, Erich

doi:10.4319/lo.2005.50.1.0207

Cited by 81 publications

(87 citation statements)

References 17 publications

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“…An asymmetric basin shape breaks the symmetry of the velocity field in the upper layer and increases the maximum correlation between the upper-layer velocity and wind stress, allowing preferential excitation of higher horizontal modes even by spatially uniform wind. This would explain why internal waves of higher horizontal modes have been observed in other lakes with irregular shape (e.g., Wang et al 2000;Lemmin et al 2005).…”

Section: Discussionmentioning

confidence: 96%

“…1c), and continuity of displacements and volume fluxes were applied to the upper layer. Since the method assumes infinitely small amplitude, the boundary condition applied to the lower layer was essentially the same as the method used by Bä uerle (1985) and Lemmin et al (2005), who assumed a vertical wall along the line where the thermocline intersected the bottom and neglected the shallow coastal regions. Note that the inclusion of the shallow regions did not affect the self-adjointness of K and properties of the associated modes (see Web Appendix 1).…”

Section: Modal Analysis Of Lake Biwamentioning

confidence: 99%

“…Unlike previous studies (Bä uerle 1985; Lemmin et al 2005), regions shallower than the thermocline were included in the calculation. Wherever the interface intersected the bottom, the volume flux normal to the horizontal boundary in the lower layer was set to zero (the boundary was assumed to be locally vertical; see Fig.…”

Section: Modal Analysis Of Lake Biwamentioning

confidence: 99%

“…Basic equations and solutions-The modal analysis used in this paper is based on the linearized shallow-water equations for a layer-stratified system using the Boussinesq and hydrostatic approximations (e.g., Monismith 1985;Lemmin et al 2005). For an incompressible fluid in a two-layer system, multiplying the equation of conservation of mass for the upper (lower) layer by the acceleration due to gravity (reduced gravity) and including layer thickness in the equations of motion gives:…”

Section: Theory Of Modal Analysismentioning

confidence: 99%

“…This technique has been previously used to analyze the horizontal structure of tides and seiches in homogeneous basins (Platzman 1972;Rao and Schwab 1976) and internal waves in stratified basins (Bä uerle 1985;Lemmin et al 2005). However, the analysis also enables us to derive a set of decoupled evolutionary equations for the individual modes (e.g., Proudman 1928;Lighthill 1969;Platzman 1984) that describe the effects of winds on the primary motions.…”

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confidence: 99%

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Horizontal structure and excitation of primary motions in a strongly stratified lake

Shimizu

Imberger

Kumagai

2007

Limnology & Oceanography

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A modal analysis in the horizontal plane was extended to a layer-stratified basin with irregular bathymetry, and the theory was applied to Lake Biwa to investigate the horizontal structure and excitation of the basin-scale internal waves and gyres. The horizontal structure of the basin-scale internal waves consisted of cyclonic and anticyclonic elliptic cells, each of which appeared to follow the dispersion relationship of Kelvin and Poincaré waves in elliptic basins. The internal waves were preferentially excited depending on the arrangement of the cells and the wind direction, but the spatial distribution of wind stress curl over the lake primarily determined the horizontal structure of the ensuing gyres. Decoupled evolutionary equations for the individual modes provided a good approximation for excitation of the internal waves and early stages of excitation of the gyres before nonlinear effects and damping become significant. The modal decomposition of hydrodynamic simulation results also showed that the primary action of the wind was to excite the internal waves; however, these internal waves were damped within a few days, and the dynamics during calm periods were dominated by the gyres, illustrating the importance of internal waves on mixing and gyres on long-term horizontal transport.

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Section: Discussionmentioning

confidence: 96%

Section: Modal Analysis Of Lake Biwamentioning

confidence: 99%

Section: Modal Analysis Of Lake Biwamentioning

confidence: 99%

Section: Theory Of Modal Analysismentioning

confidence: 99%

mentioning

confidence: 99%

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Horizontal structure and excitation of primary motions in a strongly stratified lake

Shimizu

Imberger

Kumagai

2007

Limnology & Oceanography

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A modeling approach to identify the effective forcing exerted by wind on a prealpine lake surrounded by a complex topography

Valerio

Cantelli

Monti

et al. 2017

Water Resources Research

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The representation of spatial wind distribution is recognized as a serious difficulty when modeling the hydrodynamics of lakes surrounded by a complex topography. To address this issue, we propose to force a 3‐D lake model with the wind field simulated by a high‐resolution atmospheric model, considering as a case study a 61 km2 prealpine lake surrounded by mountain ranges that reach 1800 m above the lake's surface, where a comprehensive data set was available in the stratified season. The improved distributed description of the wind stress over the lake surface led to a significant enhancement in the representation of the main basin‐scale internal wave motions, and hence provided a reference solution to test the use of simplified approaches. Moreover, the analysis of the power exerted by the computed wind field enabled us to identify measuring stations that provide suitable wind data to be applied uniformly on the lake surface in long‐term simulations. Accordingly, the proposed methodology can contribute to reducing the uncertainties associated with the definition of wind forcing for modeling purposes and can provide a rational criterion for installing representative measurement locations in prealpine lakes.

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Nonlinear Dynamics of the Nearshore Boundary Layer of a Large Lake (Lake Geneva)

et al. 2018

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We examine nearshore and pelagic current variability in Lake Geneva, a large and deep lake in western Europe, using observations from several measurement locations and a three‐dimensional numerical model for the period 2014–2016. Linear internal seiche modes excited by wind forcing clearly appear as peaks in the energy spectra for measurements in offshore locations. In contrast, spectra from the nearshore data, where currents interact with the lake bed, reveal a negligible contribution of internal seiches to the total kinetic energy. A similar contrast is seen in the spectra obtained from the numerical model at the same locations. Comparing the contribution of the different terms in the vertically averaged momentum equation from the modeling results shows that the nonlinear advective term dominates in the nearshore boundary layer. Its contribution decays with distance from shore. The width of this nearshore boundary layer, which may extend for several kilometers, seems to be mainly determined by local topography. Both field measurements and modeling results indicate that nonlinear dynamics are of primary importance in the nearshore boundary layer.

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Internal seiche dynamics in Lake Geneva

Cited by 81 publications

References 17 publications

Horizontal structure and excitation of primary motions in a strongly stratified lake

Horizontal structure and excitation of primary motions in a strongly stratified lake

A modeling approach to identify the effective forcing exerted by wind on a prealpine lake surrounded by a complex topography

Nonlinear Dynamics of the Nearshore Boundary Layer of a Large Lake (Lake Geneva)

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