Internal Waves in the Gulf of California

Citation

Munk, Walter Heinrich (1940) Internal Waves in the Gulf of California. Master's thesis, California Institute of Technology. doi:10.7907/ZJY3-GN77. https://resolver.caltech.edu/CaltechETD:etd-06162004-140251

Abstract

Between February 13 and March 19 1939 the "E.W. Scripps", research vessel of the Scripps Institution of Oceanography, occupied 53 oceanographic stations in the Gulf of California. The observations of temperature, salinity and oxygen content, which at every station were taken at a series of depths, suggested the existence of internal waves with amplitudes as large as one tenth the depth of the Gulf.

Waves generally can be classified into short and long waves and both groups comprise surface and internal waves, with frequencies corresponding to free or forced oscillations, and of the standing or progressive wave types. Those under consideration are of the "long, internal, free, standing wave" type, perhaps the least known of the sixteen possible combinations. It is the object of this paper to present a discussion of these waves from both an observational and theoretical point of view and to compare the results.

The bottom topography of the Gulf is quite complicated but the average depth remains nearly constant to a considerable distance from the entrance and decreases then regularly. We know qualitatively that velocity of propagation decreases with decreasing depth. With this in mind we first find that all observations can be combined to a consistent picture from which we obtain the period of oscillation and the wavelengths.

A theoretical treatment of the outer portion of the Gulf, applying FJELDSTAD's theory for internal waves at constant depth (1) yields results in good agreement with those indicated by observation. For the inner portion of the Gulf a general theory for internal waves in a basin of non-constant depth is developed and applied. FJELDSTAD's theory is also expanded to include the case of a horizontal density gradient.

The results of the theory, applied to the Gulf of California, compare favorably to those obtained by the observational approach.

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