Abstract

The colourful bands of Jupiter are sustained by intense east-west winds called zonal jets, which extend well below Jupiter’s weather layer into its mantle of liquid hydrogen. These jets constitute a fascinating natural example of how a rapidly-rotating turbulent flow self-organises at large scale. Despite decades of observations and modelling, understanding the long-term, nonlinear equilibration of zonal jets and the feedback with the underlying turbulence and waves is still a challenge. In this seminar, I will discuss the dynamics of zonal jets from a wave-mean flow interaction perspective, using a combination of rapidly-rotating laboratory experiments, numerical models and theoretical analyses. I will highlight the essential role of Rossby waves in the emergence and nonlinear saturation of turbulent jets, as demonstrated experimentally and theoretically with a simple quasi-linear model. Following a similar approach as in the Holton-Lindzen-Plumb model for mean flow reversals in stratified fluids, I will extend this quasi-linear analytical model to study jets’ coarsening, and discuss the final scale and amplitude of zonal winds when they are locally versus globally-driven.