Internal solitons in the ocean

Abstract

Nonlinear internal waves in the ocean are discussed (a) from the standpointof soliton theory and (b) from the viewpoint of experimental measurements.First, theoretical models for internal solitary waves in the oceanare briefly described.Various nonlinear analytical solutions aretreated, commencing with the well-known Boussinesq and Korteweg-deVriesequations. Then certain generalizations are considered, includingeffects of cubic nonlinearity, Earth's rotation, cylindrical divergence,dissipation, shear flows, and others. Recent theoretical models forstrongly nonlinear internal waves are outlined. Second, examplesof experimental evidence for the existence of solitons in the upperocean are presented; the data include radar and optical images andin situ measurements of waveforms, propagation speeds, and dispersioncharacteristics. Third, and finally, action of internal solitonson sound wave propagation is discussed. This review paper is intendedfor researchers from diverse backgrounds, including acousticians,who may not be familiar in detail with soliton theory. Thus, it includesan outline of the basics of soliton theory. At the same time, recenttheoretical and observational results are described which can alsomake this review useful for mainstream oceanographers and theoreticians.