Internal wave generation from rough topography
نویسندگان
چکیده
Through laboratory experiments we examine internal wave generation above and in the lee of finite-amplitude periodic topography having various degrees of roughness. We show that internal waves are generated not only by flow over the hills but also by flow over “boundary-trapped” lee waves and by vigorous turbulence created in the lee of sharp-crested hills. For low values of the excitation frequency, linear theory well predicts the internal wave frequencies but significantly overestimates the wave amplitudes because it neglects processes associated with boundary layer separation. When the excitation frequency exceeds the buoyancy frequency, turbulence results in the excitation of internal waves with frequencies approximately 0.72±0.05 of the buoyancy frequency and vertical displacement amplitudes ranging between 1.5% and 2% of the horizontal wavelength. © 2006 American Institute of Physics. DOI: 10.1063/1.2214538
منابع مشابه
Effects of Small-scale Bathymetric Roughness on the Global Internal Wave Field
The small-scale roughness properties of the seafloor are increasingly being recognized as critical parameters in determining important processes in physical oceanography. For instance, in situ observations (e.g., Polzin et al., 1997) find that mixing levels are greatly elevated in regions of rough topography. Gille et al. (2000) demonstrate that mesoscale eddy energy tends to be lower in areas ...
متن کاملStratified Flow over Topography: Wave Generation and Boundary Layer Separation
We have performed laboratory experiments to study wave generation over and in the lee of model topography. We have chosen to use periodic, finite-amplitude hills which are representative of the Earth’s major mountain ranges as well as the repetitious topographic features of the ocean floor. The topographic shapes are selected to encompass varying degrees of roughness, from smoothly-varying sinu...
متن کاملLarge-amplitude internal wave generation in the lee of step-shaped topography
Laboratory experiments show that as uniformly stratified fluid flows over a smoothly-varying step, two wave-like phenomena result: boundary-trapped lee waves, characterized by an undular shear layer downstream of the base of the step, and internal waves, which propagate vertically away from the step. The frequency of both types of waves is an approximately constant fraction of the buoyancy freq...
متن کاملProgress Report: Effects of Small- Scale Bathymetric Roughness on the Global Internal Wave Field
The small-scale roughness properties of the seafloor are increasingly being recognized as critical parameters in determining important processes in physical oceanography. For instance, in situ observations (e.g., Polzin et al., 1997) find that mixing levels are greatly elevated in regions of rough topography. Gille et al. (2000) demonstrate that mesoscale eddy energy tends to be lower in areas ...
متن کاملInternal wave generation in a global baroclinic tide model
The energy flux out of barotropic tides and into internal waves (‘‘conversion’’) is computed using a global domain multi-layer numerical model. The solution is highly baroclinic and reveals a global field of internal waves radiating way from generation sites of rough topography. A small number of sites where intense internal wave generation occurs accounts for most of the globally integrated wo...
متن کامل