Concerning the Effect of Sea Currents on Free Internal Gravitational Waves (K Voprosu o Vliyanii Morskikh Techeniy na Svobodnyye Vnutrenniye Gravitatsionnyye Volny),
NAVAL INTELLIGENCE SUPPORT CENTER WASHINGTON D C TRANSLATION DIV
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Free internal gravitational waves arise as a reaction of a stably stratified heterogeneous liquid to an energetic external action. They carry energy from the region of an initial disturbance to the ambient space, tending to return the liquid to the initial state of equilibrium. In the majority of theoretical studies of free internal gravitational waves in the ocean, the basic assumption is that they are small harmonic oscillations of an ideal incompressible liquid about a certain state of equilibrium. The state of rest is usually taken as this state of equilibrium. In this case, the system of fluid mechanics equations describing the unperturbed state of equilibrium is reduced to a single equation of statics. Such a choice of the principal state is equivalent to neglecting the convection terms in linearized equations for perturbations, in comparison with local changes. V. Krauss notes that this operation is inadmissible in the study of tidal internal waves. A similar situation arises in the study of other types of internal gravitational waves, whose phase velocities are comparable to the velocities of sea currents existing in the initial state of equilibrium. Since the spectrum of phase velocities of internal gravitational waves in the ocean is fairly wide, and a certain average transport of waters is the rule rather than the exception for all regions of the World Ocean, it appears that sea currents the main flow must be considered in order to explain many aspects of the dynamics of internal gravitational waves.
- Physical and Dynamic Oceanography
- Fluid Mechanics