In the first part of the seminar, I will focus on the complex, multiscale dynamics that takes place in gas giant’s atmospheres and below, in their liquid hydrogen. Jupiter’s atmosphere exhibits strong large-scale east-west winds called zonal jets, which self-organize from the underlying intense turbulent flow. I will present idealized laboratory experiments complemented by numerical and theoretical analyses to model the emergence of zonal jets and better understand their final properties. I will describe an experimental setup where dominant zonal jets emerge spontaneously from a rapidly rotating turbulent flow with a topographic beta-effect. The experiments exhibit two regimes of zonal jets with bistability, and demonstrate the essential role of Rossby waves in the emergence and nonlinear saturation of the jets. In addition, the properties of the turbulent flow in the most extreme regime are consistent with the so-called zonostrophic turbulence regime, relevant to the gas giants.

In a second part, I will leave Jupiter and focus on the fluid dynamics involved in the subsurface oceans of its icy moons, such as Europa. The global ocean in icy moons is a key layer, responsible for coupling the deep interior to the observed ice crust, via material and heat exchanges. Using direct numerical simulations in rotating spherical shells, I investigate how the tidal heating within the silicate mantle can affect the rotating thermal convection in Europa’s ocean. In particular, the tidal heating is spatially heterogeneous (larger at the poles, with longitudinal variations of order 2 in the equatorial region). These heating horizontal variations can drive “thermal winds” which would significantly change the general circulation in the ocean compared to a homogeneous heating. These results suggest that if tidal heating is dominant in the silicate mantle, its pattern could be transposed up to the ice despite the dynamic ocean lying between the ice crust and the rocky mantle.

Getting here

Add event to calendar
See all events