Inertial waves in planetary fluid layers: excitation, instabilities, and possible consequences.

International audienceA huge amount of energy is stored in the spin and orbital motions of planets, and under certain circumstances, harmonic forcings such as libration, precession and tides, are capable of conveying a portion of this energy to drive intense three-dimensional flows in their liquid layers (atmospheres, oceans, cores…). Relevant physical mechanisms encompass resonant forcing of inertial waves, zonal jet generation by their non-linear interaction, and the excitation of parametric instabilities. Beyond the well-studied motions driven by convection, those often-neglected flows could have important consequences on the heat budget, magnetic field, internal structure and temporal evolution of celestial bodies. I will present recent progresses in the understanding of the response of rotating flows to harmonic forcing coming from experimental, numerical and theoretical studies. I will then illustrate the relevance of the described processes at the planetary scale in the view of the latest observational data of our solar system moons and planets as well as of more exotic extrasolar systems, which have highlighted the need to go beyond the standard models