PSD in turbulence
As mentioned in the previous courses, one reason of the complexity of the environmental systems lies in the wide range of scale involved in the evolution of theses systems. Theses range of scale are not only numerous, but they interact with each other. Spectral analysis allows us to understand which kind of process is occurring and which range of scale is involved in. The scale invariance propriety can be assessed with spectral analysis : In log-log plot if the field is scaling, the spectral exponent is its slope.
In turbulence, the PSD describe how the energy is transferred from the large eddies to the smaller one, according to the Lewis Richardson cascade :
Information[1]Big whorls have little whorls that feed on their velocity, and little whorls have
smaller whorls and so on to viscosity in the molecular sense.
