Quantification of Internal Wave Energy

I propose a methodology for estimating internal wave energy from single-point velocity vector and density observations in stratified laboratory experiments or in estuarine, coastal and oceanographic flows. In literature the 90° phase shift between density (ρ) and vertical velocity (w) fluctuations in estuarine or atmospheric flows is used as indicator of internal wave motions. Some references apply quadrature spectra i.e. the imaginary part of the ρ-w cross spectra or apply the closely related coherence function. All such methods indicate the relative importance of internal wave motions over turbulence rather than estimating the Internal Wave Energy (IWE) proper.

 My IWE estimator is founded on the properties of internal waves in density-stratified shear flows and the estimator is based on the three quadrature spectra of density and the three orthogonal velocity components. The accuracy of my IWE estimator is demonstrated by computer-generated internal wave signals based on exact defined spectra of internal waves, and IWE, having mutually different phase angles as well as angles of propagation relative to a horizontal flow vector.