Abstract
The ice shell of Jupiter’s moon Europa is marked by regions of disrupted ice known as chaos terrains that cover up to 40% of the satellite’s surface, most commonly occurring within 40° of the equator1. Concurrence with salt deposits2 implies a coupling between the geologically active ice shell and the underlying liquid water ocean at lower latitudes. Europa’s ocean dynamics have been assumed to adopt a two-dimensional pattern3,4,5,6,7,8, which channels the moon’s internal heat to higher latitudes. Here we present a numerical model of thermal convection in a thin, rotating spherical shell where small-scale convection instead adopts a three-dimensional structure and is more vigorous at lower latitudes. Global-scale currents are organized into three zonal jets and two equatorial Hadley-like circulation cells. We find that these convective motions transmit Europa’s internal heat towards the surface most effectively in equatorial regions, where they can directly influence the thermo-compositional state and structure of the ice shell. We suggest that such heterogeneous heating promotes the formation of chaos features through increased melting of the ice shell and subsequent deposition of marine ice at low latitudes. We conclude that Europa’s ocean dynamics can modulate the exchange of heat and materials between the surface and interior and explain the observed distribution of chaos terrains.
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Acknowledgements
This work was supported by the Institute for Geophysics of the Jackson School of Geosciences at The University of Texas at Austin (UTIG). Computational resources were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. We thank M. Heimpel for providing the jovian-like model data in Fig. 1, T. Doggett for providing the geologic map of Europa in Supplementary Fig. 1, and J. Aurnou for providing Supplementary Fig. 2. This is UTIG contribution 2637.
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K.M.S. and B.E.S. conceived of this project and wrote the paper. K.M.S. did all calculations and carried out the simulation. J.W. provided the numerical model and contributed to the convective regime transition arguments. D.D.B. contributed to the terrestrial analogue arguments. All authors discussed the results and commented on the manuscript.
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Soderlund, K., Schmidt, B., Wicht, J. et al. Ocean-driven heating of Europa’s icy shell at low latitudes. Nature Geosci 7, 16–19 (2014). https://doi.org/10.1038/ngeo2021
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DOI: https://doi.org/10.1038/ngeo2021
