Open AccessInternal wave–turbulence pressure above sloping sea bottoms
Author(s) -
Haren Hans
Publication year - 2011
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jc007085
Subject(s) - internal wave , geology , turbulence , buoyancy , hydrostatic pressure , hydrostatic equilibrium , gravity wave , spectral line , oceanography , geophysics , meteorology , wave propagation , physics , mechanics , optics , quantum mechanics , astronomy
An accurate bottom pressure sensor has been moored at different sites varying from a shallow sea strait via open ocean guyots to a 1900 m deep Gulf of Mexico. All sites show more or less sloping bottom topography. Focusing on frequencies ( σ ) higher than tidal, the pressure records are remarkably similar, to within the 95% statistical significance bounds, in the internal gravity wave continuum (IWC) band up to buoyancy frequency N. The IWC has a relatively uniform spectral slope: log(P( σ )) = − α log( σ ), α = 2 ± 1/3. The spectral collapse is confirmed from independent internal hydrostatic pressure estimate, which suggests a saturated IWC. For σ > N, all pressure‐spectra transit to a bulge that differs in magnitude. This bulge is commonly attributed to long surface waves. For the present data it is suggested to be due to stratified turbulence–internal wave coupling, which is typically large over sloping topography. The bulge drops off at a more or less common frequency of 2–3 × 10 −2 Hz, which is probably related with typical turbulent overturning scales.