Introduction
We introduce in this lecture the spectral analysis which is based on the Fourier transform. The main objective of using this can of analysis in our studies is to check the scale invariance propriety of the studied field and also to identify the involved processes. The spectral analysis is widely used in fluid dynamics especially in turbulence field. We will show in this lesson that the spectrum of the studied field in log-log plot is characterized by a given slope which allows us to identify the involved process. We will start this lesson by an introduction to the Fourier transform and the discrete Fourier transform, after that we will mention some domain of application of the spectral analysis and we will finish by the identification of some process in geophysics.
