Presented here is a model for determining the characteristic parameters of an internalwave field using cross spectra of data obtained from vertically separated and/or horizontally separated moored instruments. The model is based on the assumption that the motion consists mainly of linear free internal waves having random phase relationships. The internalwave energy is supposed to be distributed among a finite number of modes having continuous directional distribution....
Schott, Friedrich, and Jürgen Willebrand. 1973. "On the determination of internal-wave directional spectra from moored instruments." Journal of Marine Research 31, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1262