Rotating thermal convection: surface turbulence observed with altimetry and thermal radiometry

Abstract

The surface dynamics of the rotating thermal convection are examined in finely resolved laboratory flows. Deep rotating convection creates geostrophic turbulent flow at the surface, the regime of convection relevant to flows observed in deep convection sites in the ocean or in the atmospheres of the gas giants Jupiter and Saturn. Spectral analyses reveal a dual energy cascade of the surface kinetic energy and a downscale cascade of surface buoyancy. The spectral slopes of these quantities are found to be very similar to each other. This property is further confirmed theoretically; it was showed in particular that buoyancy is proportional to velocity in the subsurface thermal boundary layer.