Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Dynamics of the global meridional ice flow of Europa’s icy shell



Europa is one of the most probable places in the solar system to find extra-terrestrial life1,2, motivating the study of its deep (~100 km) ocean3,4,5,6 and thick icy shell3,7,8,9,10,11. The chaotic terrain patterns on Europa’s surface12,13,14,15 have been associated with vertical convective motions within the ice8,10. Horizontal gradients of ice thickness16,17 are expected due to the large equator-to-pole gradient of surface temperature and can drive a global horizontal ice flow, yet such a flow and its observable implications have not been studied. We present a global ice flow model for Europa composed of warm, soft ice flowing beneath a cold brittle rigid ice crust3. The model is coupled to an underlying (diffusive) ocean and includes the effect of tidal heating and convection within the ice. We show that Europa’s ice can flow meridionally due to pressure gradients associated with equator-to-pole ice thickness differences, which can be up to a few km and can be reduced both by ice flow and due to ocean heat transport. The ice thickness and meridional flow direction depend on whether the ice convects or not; multiple (convecting and non-convecting) equilibria are found. Measurements of the ice thickness and surface temperature from future Europa missions18,19 can be used with our model to deduce whether Europa’s icy shell convects and to constrain the effectiveness of ocean heat transport.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Equilibrium state of the icy shell of Europa when the meridional ocean heat transport and ice convection are not included.
Fig. 2: Equilibrium state of the icy shell of Europa when ocean heat transport is included, while ice convection is absent.
Fig. 3: Equilibrium solutions when meridional ocean heat transport is absent and ice convection is active.
Fig. 4: Observational predictions and verification.


  1. 1.

    Hand, K., Chyba, C., Priscu, J., Carlson, R. & Nealson, K. in Europa (Space Science Series) (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K.) 589–629 (Univ. Arizona Press, Tucson, AZ, 2009).

  2. 2.

    Vance, S., Hand, K. & Pappalardo, R. Geophysical controls of chemical disequilibria in Europa. Geophys. Res. Lett. 43, 4871–4879 (2016).

    ADS  Article  Google Scholar 

  3. 3.

    Pappalardo, R. T. et al. Geological evidence for solid-state convection in Europa’s ice shell. Nature 391, 365–368 (1998).

    ADS  Article  Google Scholar 

  4. 4.

    Kivelson, M. G. et al. Galileo magnetometer measurements: a stronger case for a subsurface ocean at Europa. Science 289, 1340–1343 (2000).

    ADS  Article  Google Scholar 

  5. 5.

    Travis, B., Palguta, J. & Schubert, G. A whole-moon thermal history model of Europa: impact of hydrothermal circulation and salt transport. Icarus 218, 1006–1019 (2012).

    ADS  Article  Google Scholar 

  6. 6.

    Roth, L. et al. Transient water vapor at Europa’s south pole. Science 343, 171–174 (2014).

    ADS  Article  Google Scholar 

  7. 7.

    Hussmann, H., Spohn, T. & Wieczerkowski, K. Thermal equilibrium states of Europa’s ice shell: implications for internal ocean thickness and surface heat flow. Icarus 156, 143–151 (2002).

    ADS  Article  Google Scholar 

  8. 8.

    O’Brien, D. P., Geissler, P. & Greenberg, R. A. A melt through model for chaos formation on Europa. Icarus 156, 152–161 (2002).

    ADS  Article  Google Scholar 

  9. 9.

    Tobie, G., Choblet, G. & Sotin, C. Tidally heated convection: constraints on Europa’s ice shell thickness. J. Geophys. Res. 108, 5124 (2003).

    Article  Google Scholar 

  10. 10.

    Schenk, P. & Pappalardo, R. T. Topographic variations in chaos on Europa: implications for diapiric formation. Geophys. Res. Lett. 31, L16703 (2004).

    ADS  Article  Google Scholar 

  11. 11.

    Zhu, P., Manucharyan, G. E., Thompson, A. F., Goodman, J. C. & Vance, S. D. The influence of meridional ice transport on Europa’s ocean stratification and heat content. Geophys. Res. Lett. 44, 5969–5977 (2017).

  12. 12.

    Pappalardo, R. et al. Does Europa have a subsurface ocean? Evaluation of the geological evidence. J. Geophys. Res. 104, 24015–24055 (1999).

    ADS  Article  Google Scholar 

  13. 13.

    Collins, G. & Nimmo, F. in Europa (Space Science Series) (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K.) 259–281 (Univ. Arizona Press, Tucson, AZ, 2009).

  14. 14.

    Goodman, J. C., Collins, G. C., Marshall, J. & Pierrehumbert, R. T. Hydrothermal plume dynamics on Europa: implications for chaos formation. J. Geophys. Res. 109, E03008 (2004).

  15. 15.

    Goodman, J. C. & Lenferink, E. Numerical simulations of marine hydrothermal plumes for Europa and other icy worlds. Icarus 221, 970–983 (2012).

    ADS  Article  Google Scholar 

  16. 16.

    Ojakangas, G. W. & Stevenson, D. J. Thermal state of an ice shell on Europa. Icarus 81, 220–241 (1989).

    ADS  Article  Google Scholar 

  17. 17.

    Nimmo, F., Thomas, P., Pappalardo, R. & Moore, W. The global shape of Europa: constraints on lateral shell thickness variations. Icarus 191, 183–192 (2007).

    ADS  Article  Google Scholar 

  18. 18.

    Grasset, O. et al. JUpiter ICy moons Explorer (JUICE): an ESA mission to orbit Ganymede and to characterise the Jupiter system. Planet. Space Sci. 78, 1–21 (2013).

    ADS  Article  Google Scholar 

  19. 19.

    Pappalardo, R. et al. Science objectives and capabilities of the NASA Europa mission. In Lunar and Planetary Science Conf. 47, 3058 (Lunar and Planetary Institute, 2016).

  20. 20.

    Billings, S. E. & Kattenhorn, S. A. The great thickness debate: ice shell thickness models for Europa and comparisons with estimates based on flexure at ridges. Icarus 177, 397–412 (2005).

    ADS  Article  Google Scholar 

  21. 21.

    Quick, L. C. & Marsh, B. D. Constraining the thickness of Europa’s water–ice shell: insights from tidal dissipation and conductive cooling. Icarus 253, 16–24 (2015).

    ADS  Article  Google Scholar 

  22. 22.

    Chen, E. M. A., Nimmo, F. & Glatzmaier, G. A. Tidal heating in icy satellite oceans. Icarus 229, 11–30 (2014).

    ADS  Article  Google Scholar 

  23. 23.

    Squyres, S. W., Reynolds, R. T., Cassen, P. & Peale, S. J. Liquid water and active resurfacing on Europa. Nature 301, 225–226 (1983).

    ADS  Article  Google Scholar 

  24. 24.

    Spencer, J. R., Tamppari, L. K., Martin, T. Z. & Travis, L. D. Temperatures on Europa from Galileo photopolarimeter-radiometer: nighttime thermal anomalies. Science 284, 1514–1516 (1999).

    ADS  Article  Google Scholar 

  25. 25.

    Ashkenazy, Y. et al. Dynamics of a Snowball Earth ocean. Nature 495, 90–93 (2013).

    ADS  Article  Google Scholar 

  26. 26.

    Hutter, K. Theoretical Glaciology: Material Science of Ice and the Mechanics of Glaciers and Ice Sheets. (Reidel, Dordrecht, 1983).

    Book  Google Scholar 

  27. 27.

    Barr, A. C. & Showman, A. P. in Europa (Space Science Series) (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K.) 405–430 (Univ. Arizona Press, Tucson, AZ, 2009).

  28. 28.

    Soderlund, K. M., Schmidt, B. E., Wicht, J. & Blankenship, D. D. Ocean-driven heating of Europa’s icy shell at low latitudes. Nat. Geosci. 7, 16–19 (2014).

    ADS  Article  Google Scholar 

  29. 29.

    Ashkenazy, Y. & Tziperman, E. Variability, instabilities and eddies in a Snowball ocean. J. Clim. 29, 869–888 (2016).

    ADS  Article  Google Scholar 

  30. 30.

    Jansen, M. F. The turbulent circulation of a Snowball Earth ocean. J. Phys. Oceanogr. 46, 1917–1933 (2016).

    ADS  Article  Google Scholar 

  31. 31.

    Han, L. & Showman, A. P. Thermo-compositional convection in Europa’s icy shell with salinity. Geophys. Res. Lett. 32, L20201 (2005).

  32. 32.

    Zolotov, M. Y. & Kargel, J. in Europa (Space Science Series) (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K.) 431–457 (Univ. Arizona Press, Tucson, AZ, 2009).

  33. 33.

    Sotin, C., Tobie, G., Wahr, J. & McKinnon, W. B. in Europa (Space Science Series) (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K.) 85–117 (Univ. Arizona Press, Tucson, AZ, 2009).

  34. 34.

    Mitri, G. & Showman, A. P. Convective–conductive transitions and sensitivity of a convecting ice shell to perturbations in heat flux and tidal-heating rate: implications for Europa. Icarus 177, 447–460 (2005).

    ADS  Article  Google Scholar 

  35. 35.

    Kalousová, K., Schroeder, D. M. & Soderlund, K. M. Radar attenuation in Europa’s ice shell: obstacles and opportunities for constraining the shell thickness and its thermal structure. J. Geophys. Res. Planets 122, 524–545 (2017).

    ADS  Article  Google Scholar 

  36. 36.

    Ashkenazy, Y. The surface temperature of Europa. Preprint at (2017).

  37. 37.

    Tziperman, E. et al. Continental constriction and sea ice thickness in a Snowball-Earth scenario. J. Geophys. Res. 117, C05016 (2012).

  38. 38.

    Spohn, T., Breuer, D. & Johnson, T. in Encyclopedia of the Solar System (eds Prockter, L. M. & Pappalardo, R. T.) Ch. 36 (Elsevier, 2014).

  39. 39.

    Goodman, J. C. & Pierrehumbert, R. T. Glacial flow of floating marine ice in “Snowball Earth”. J. Geophys. Res. 108, 3308 (2003).

  40. 40.

    Glen, J. W. The creep of polycrystalline ice. Proc. R. Soc. Lond. A Math. Phys. Eng. Sci. 228, 519–538 (1955).

    ADS  Article  Google Scholar 

  41. 41.

    Goldsby, D. & Kohlstedt, D. Superplastic deformation of ice: experimental observations. J. Geophys. Res. 106, 11017–11030 (2001).

    ADS  Article  Google Scholar 

  42. 42.

    Durham, W. & Stern, L. Rheological properties of water ice-applications to satellites of the outer planets 1. Annu. Rev. Earth Planet. Sci. 29, 295–330 (2001).

    ADS  Article  Google Scholar 

  43. 43.

    Cuffey, K. M. & Paterson, W. S. B. The Physics of Glaciers (Academic Press, 2010).

  44. 44.

    Nimmo, F. & Gaidos, E. Strike–slip motion and double ridge formation on Europa. J. Geophys. Res. 107, E4 (2002).

  45. 45.

    Mohr, P. J., Newell, D. B. & Taylor, B. N. Codata recommended values of the fundamental physical constants: 2014. J. Phys. Chem. Ref. Data 45, 043102 (2016).

    ADS  Article  Google Scholar 

  46. 46.

    Schulson, E. M. & Duval, P. Creep and Fracture of Ice (Cambridge Univ. Press, Cambridge, 2009).

    Book  Google Scholar 

  47. 47.

    Holland, D. M. & Jenkins, A. Modeling thermodynamic ice–ocean interactions at the base of an ice shelf. J. Phys. Oceanogr. 29, 1787–1800 (1999).

    ADS  Article  Google Scholar 

  48. 48.

    MITgcm MITgcm User Manual. (MIT/EAPS, Cambridge, MA, 2010);

  49. 49.

    Ashkenazy, Y., Gildor, H., Losch, M. & Tziperman, E. Ocean circulation under globally glaciated Snowball Earth conditions: steady state solutions. J. Phys. Oceanogr. 44, 24–43 (2014).

    ADS  Article  Google Scholar 

  50. 50.

    Pollard, D. & Kasting, J. F. Snowball Earth: a thin-ice solution with flowing sea glaciers. J. Geophys. Res. 110, C07010 (2005).

    ADS  Article  Google Scholar 

  51. 51.

    McDougall, T. J. & Barker, P. M. Getting Started With TEOS-10 and the Gibbs Seawater (GSW) Oceanographic Toolbox (2011).

  52. 52.

    Losch, M. Modeling ice shelf cavities in a z-coordinate ocean general circulation model. J. Geophys. Res. 113, C08043 (2008).

    ADS  Article  Google Scholar 

  53. 53.

    Hand, K. P. & Chyba, C. F. Empirical constraints on the salinity of the europan ocean and implications for a thin ice shell. Icarus 189, 424–438 (2007).

    ADS  Article  Google Scholar 

Download references


E.T. was funded by the National Aeronautics and Space Administration Habitable Worlds programme (grant FP062796-A) and thanks the Weizmann Institute for its hospitality during parts of this work.

Author information




Y.A. and E.T. formulated the problem and performed the model runs and analyses. All authors contributed to the development of the model and the writing of the paper.

Corresponding author

Correspondence to Yosef Ashkenazy.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Electronic supplementary material

Supplementary Information

Supplementary Figures 1–6, Supplementary Table 1, Supplementary References.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Ashkenazy, Y., Sayag, R. & Tziperman, E. Dynamics of the global meridional ice flow of Europa’s icy shell. Nat Astron 2, 43–49 (2018).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing