SUMMARY 



Internal-wave literature originating in western 

 countries, plus a few papers from Soviet and Chinese 

 works, totals about 350 documents. Most deal with internal 

 sea waves, but a few papers on internal waves in the atmos- 

 phere are included to serve as a cross section of the litera- 

 ture. Similar theory applies to both media. The complete 

 bibliography on internal waves in the atmosphere probably 

 would be more extensive than the bibliography on internal 

 waves in the ocean, because meteorology is more advanced 

 than oceanography by several decades. A second considera- 

 tion is that all pertinent U. S. S. R. and Asian literature is 

 undoubtedly not included here. The language barrier and 

 political conflict hamper communication to such an extent 

 that a comprehensive bibliography on eastern literature 

 would be impossible to compile. 



Theory and observation of internal waves are incom- 

 plete and largely unrelated. Nonlinear theories of internal 

 waves have been given little attention. Most present theory 

 is kept linear by the neglect of higher-order terms. The 

 theory of infinitesimal waves, very small in amplitude com- 

 pared to length, is well developed. Finite -amplitude inter- 

 nal waves have been observed on both the west and east 

 coasts of the United States. This directly indicates that a 

 nonlinear theory is necessary for full understanding of in- 

 ternal waves in the ocean. 



The equations of motion that govern internal waves 

 are known for a medium with a continuous density distribu- 

 tion over depth and for mean motion that is constant over 

 depth. Solutions of the equations have been obtained for 

 plane boundaries or boundaries of intersecting planes. 

 Solutions have been recently obtained for an irregular bot- 

 tom by the use of perturbation methods. Internal waves 

 originate by flow over an irregular bottom, by atmospheric 

 disturbances, and possibly by shear flow, and theoretically 

 exist in an infinite number of modes. Free internal waves 

 are confined to a certain band of frequencies. The lower 

 limit of this frequency band confines internal waves to 

 certain limits of latitude, depending on frequency. Some 



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