The coupling of surface and internal gravity waves: revisited

Abstract

A new investigation is made of internal wave generation by surface waves. Previous theories are put into a unified form that includes a model of surface wave damping. Calculations using the complete theory, which do not seem to have been made previously, indicate that for wind speeds between 7 and 20 m s "SUP -1" the internal wave field loses about 10 "SUP -4" W m "SUP -2" to the surface wave field. This would lead to a decay time of about 10 days for the high frequency portion of the internal wave field if an energy source were not available to maintain it. Possible sources for this energy are discussed. In contrast to this result for wind waves, a strong, highly collimated ocean swell can lead to rapid growth of high frequency internal waves. The effects of nonlinear surface wave modulation and wave blocking are also discussed. (A)