2024/12/12 by T. Gastine, Gastine, T., Benjamin Favier +1 · 2 citations
Physics and Astronomy · #Astro and Planetary Science #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Geophysics (physics.geo-ph)
paper · pdf · doi:10.48550/arxiv.2412.09700
openalex publication_date 2024/12/12 · openalex created_date 2024/12/17 · openalex updated_date 2026/07/28
A better understanding of the ice-ocean couplings is required to better\ncharacterise the hydrosphere of the icy moons. Using global numerical\nsimulations in spherical geometry, we have investigated here the interplay\nbetween rotating convection and a melting boundary. To do so, we have\nimplemented and validated a phase field formulation in the open-source code\n\MagIC. We have conducted a parameter study varying the influence of\nrotation, the vigour of the convective forcing and the melting temperature. We\nhave evidenced different regimes akin to those already found in previous\nmonophasic models in which the mean axisymmetric ice crust transits from\npole-ward thinning to equator-ward thinning with the increase of the rotational\nconstraint on the flow. The derivation of a perturbative model of heat\nconduction in the ice layer enabled us to relate those mean topographic changes\nto the underlying latitudinal heat flux variations at the top of the ocean. The\nphase change has also been found to yield the formation of sizeable\nnon-axisymmetric topography at the solid-liquid interface with a typical size\nclose to that of the convective columns. We have shown that the typical\nevolution timescale of the interface increases linearly with the\ncrest-to-trough amplitude and quadratically with the mean melt radius. In the\ncase of the largest topographic changes, the convective flows become quasi\nlocked in the topography due to the constructive coupling between convection\nand ice melting. The tentative extrapolation to the planetary regimes yields\n\O(102-103) meters for the amplitude of non-axisymmetric\ntopography at the base of the ice layer of Enceladus and\n\O(103-104) meters for Titan.\n