Planetary Core‐Style Rotating Convective Flows in Paraboloidal Laboratory Experiments.

Turbulent convection in a planet's outer core is simulated here using a thermally‐driven, free surface paraboloidal laboratory annulus. We show that the rapidly rotating convection dynamics in free‐surface paraboloidal annuli are similar those in planetary spherical shell geometries. Three experimental cases are carried out, respectively, at 35 revolutions per minute (rpm), 50 and 60 rpm. Thermal Rossby waves are detected in full disk thermographic images of the fluid's free surface. Ultrasonic flow velocity measurements reveal the presence of multiple azimuthal (zonal) jets, with successively more jets forming in higher rotation rate cases. The jets' cylindrical radial extent is well approximated by the Rhines scale. Over time, the zonal jets migrate to larger radial position with migration rates in good agreement with prior theoretical estimates. Our results suggest that planetary core rotating convection will be comprised of flow structures found in other turbulent geophysical fluid dynamical systems: convective turbulence dominates the small‐scale flow field, and also act to flux energy into larger‐scale, slowly evolving zonal flow structures. How the ambient magnetic fields in planetary core settings affect such turbulent flows remains an open question. Plain Language Summary: In this study, proof‐of‐concept demonstrations are provided which show that it is possible to simulate the turbulent fluid motions occurring in Earth's remote outer core via laboratory experiments using a novel device called the Coreaboloid. We show that the Coreaboloid's parabolic free surface configuration is a good proxy for rapidly rotating dynamics in a spherical shell. In our experiments strong zonal jet flows—dynamically similar to those observed on the surfaces of the Gas Giants—emerge naturally from the convective Coreaboloidal turbulence. Further, these jets do not always stay put; in our most rapidly rotating case they slowly travel outwards in radius, an effect seen in studies of atmospheric and oceanic jet dynamics, but that has not be seen in prior experimental studies of planetary core flows. Key Points: Planetary core turbulence is simulated via a rapidly rotating annular device with a parabolic free upper fluid surfaceThermal Rossby waves are found in free surface thermography data; alternating zonal jets are detected in ultrasonic velocimetry dataThe Rhines scale jets travel in radius, in agreement with radial migration rates found in models of two‐dimensional barotropic turbulence [ABSTRACT FROM AUTHOR]