Tomographie acoustique du Léman

The main objective was to show that the acoustic tomography constitutes a new method to investigate the main hydrodynamical processes of the lake of Geneva. The work is based of the various related fields to the tomography, namely : acoustic wave propagation, signal processing and physical limnology. The development of a tomographic system was carried out so as to study the dynamics of the Great Lake by the analysis of the propagation along its small axis. This work is based on modelling of the sound propagation and its systematic comparison with experimental data. The constitution of a temperature profiles calendar is created starting from four orthogonal empirical functions constituting a fundamental information for the resolution of the tomographic problem. The modelling of the thermal destratification and of internal stationnary waves effects on the propagation validate winter measurements, which are correlated with the weather data. It is established that the qualification of the major processes controlling hydrodynamics (thermal stratification, internal waves) is possible by the analysis of sound travel times between two sites close to the banks. The main part of this work constitutes a reference for the adaptation of oceanic tomography to the case of great lakes. It suggests solutions for a best comprehension of the major processes during their phase of thermal destratification.