Application of the Wigner–Ville Distribution to Temperature Gradient Microstructure: A New Technique to Study Small-Scale Variations

The Wigner–Ville distribution, a new tool in the time–frequency analysis of signals, is applied to temperature gradient microstructure records. In particular, the Wigner–Ville distribution is used to compute the local instantaneous and maximum frequencies of the signal as a function of depth, and these frequencies are then related to the dissipation of turbulent kinetic energy. The method is applied to two temperature gradient microstructure records from the Wellington Reservoir. It is shown that a high resolution estimate of the dissipation is obtained that provides insight into the patchiness, the wavenumber content, and the Reynolds–Froude number variability of the integral scales of motion in a strongly stratified water column.