Can Jupiter's atmospheric metallicity be different from the deep interior?

Updated formation and structure models of Jupiter predict a metal-poor envelope. This is at odds with measurements of the Galileo probe, which measured an enrichment of about two to three times solar. Additionally, Juno data imply that water and ammonia are enriched compared to a solar composition. Here we explore whether Jupiter can have a deep radiative layer that separates the upper atmosphere from the deeper interior. The origin of this radiative layer could be related to a hydrogen-transparency window or a depletion of alkali metals. 

We show that the accretion of heavy elements during Jupiter's evolution can lead to the desired atmospheric enrichment and that this configuration is stable over billions of years. The origin of the heavy elements could be due to cumulative impacts of small objects or from a large impact. We conclude that most of Jupiter's molecular envelope could have a solar composition while its uppermost atmosphere is enriched with heavier elements. The origin of this enrichment is likely the accretion of solid objects. This possibility resolves the long-standing mismatch between Jupiter's interior models and measurements of its atmospheric composition. Furthermore, our results imply that the measured atmospheric composition of exoplanets does not necessarily reflect their bulk compositions. 

We also investigate the possibility of the enrichment coming from the deeper interior and show that the observed enrichment is highly unlikely due to the erosion of a dilute core. This scenario is inconsistent with evolution calculations, the suggested deep radiative layer, and published interior models.