55 research outputs found
A Hamiltonian Formulation for Long Internal Waves
A novel canonical Hamiltonian formalism is developed for long internal waves
in a rotating environment. This includes the effects of background vorticity
and shear on the waves. By restricting consideration to flows in hydrostatic
balance, superimposed on a horizontally uniform background of vertical shear
and vorticity, a particularly simple Hamiltonian structure arises, which can be
thought of as describing a nonlinearly coupled infinite collection of shallow
water systems. The kinetic equation describing the time evolution of the
spectral energy of internal waves is subsequently derived, and a stationary
Kolmogorov solution is found in the high frequency limit. This is surprisingly
close to the Garrett--Munk spectrum of oceanic internal waves
Toward Regional Characterizations of the Oceanic Internal Wavefield
Many major oceanographic internal wave observational programs of the last 4
decades are reanalyzed in order to characterize variability of the deep ocean
internal wavefield. The observations are discussed in the context of the
universal spectral model proposed by Garrett and Munk. The Garrett and Munk
model is a good description of wintertime conditions at Site-D on the
continental rise north of the Gulf Stream. Elsewhere and at other times,
significant deviations in terms of amplitude, separability of the 2-D vertical
wavenumber - frequency spectrum, and departure from the model's functional form
are noted. Subtle geographic patterns are apparent in deviations from the high
frequency and high vertical wavenumber power laws of the Garrett and Munk
spectrum. Moreover, such deviations tend to co-vary: whiter frequency spectra
are partnered with redder vertical wavenumber spectra. Attempts are made to
interpret the variability in terms of the interplay between generation,
propagation and nonlinearity using a statistical radiative balance equation.
This process frames major questions for future research with the insight that
such integrative studies could constrain both observationally and theoretically
based interpretations
The Tsunami on Sakhalin on August 2, 2007: Mareograph Evidence and Numerical Simulation
Instrumental data on the tsunami registration on Sakhalin and Hokkaido islands are presented. The numerical simulation of the tsunami propagation in the Tatar Strait was performed. The results of the calculations are in satisfactory agreement with the observed data
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