Convective outgassing efficiency in planetary magma oceans: Insights from computational fluid dynamics

Planetary atmospheres are commonly thought to result from the efficient outgassing of cooling magma oceans. During this stage, vigorous convective motions in molten interior believed rapidly transport dissolved volatiles shallow depths where they exsolve and burst at surface. This assumption degassing atmosphere formation has important implications for planetary evolution, but never been tested against fluid dynamics considerations. Yet, during a cycle, only finite fraction ocean can reach exsolution occur, large-scale circulation may prevent substantial volume reaching Therefore, we conducted computational experiments 2D 3D Rayleigh-B\'enard convection Prandtl number unity characterize ability convecting which exsolved extracted atmosphere. Outgassing efficiency is essentially function magnitude velocities. allows deriving simple expressions predict time evolution amount outgassed as governing parameters. For plausible cases, required all oversaturated water exceed lifetime given highly transient leading incomplete or even negligible outgassing. Furthermore, planet size initial content, through vigor depth, respectively, strongly affect oceans efficiency, possibly divergent paths resulting surface conditions. Overall, despite convection, significant range parameters, appears not previously thought.