Fig. 3.

Experimental setup at IRPHE, Marseille (Le Reun et al. 2019), derived from the original design of Noir et al. (2009) and Noir et al. (2012). This large ellipsoidal installation allows exploring Ekman numbers down to $Ek=3.7\times {10}^{-6}$ with turbulent flows down to an excitation Rossby number $Ro=3.4\times {10}^{-2}$, defined here as the product of the libration amplitude times the ellipticity in the equatorial plane. Hence, this setup allows characterizing the transition between the 2D geostrophic turbulence at relatively large Ro and the asymptotic, 3D wave turbulence regime at small Ro. See also online movie at https://www.youtube.com/watch?v=Drq2qxX0U90