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.

The water abundance in Jupiter’s equatorial zone


Oxygen is the most common element after hydrogen and helium in Jupiter’s atmosphere, and may have been the primary condensable (as water ice) in the protoplanetary disk. Prior to the Juno mission, in situ measurements of Jupiter’s water abundance were obtained from the Galileo probe, which dropped into a meteorologically anomalous site. The findings of the Galileo probe were inconclusive because the concentration of water was still increasing when the probe ceased sending data. Here we report on the water abundance in the equatorial region (0 to 4 degrees north latitude), based on data taken at 1.25 to 22 GHz from the Juno microwave radiometer, probing pressures of approximately 0.7 to 30 bar. Because Juno discovered the deep atmosphere to be surprisingly variable as a function of latitude, it remains to confirm whether the equatorial abundance represents Jupiter’s global water abundance. The water abundance at the equatorial region is inferred to be \(2.5_{ - 1.6}^{ + 2.2} \times 10^3\) ppm, or \(2.7_{ - 1.7}^{ + 2.4}\) times the elemental ratio of protosolar oxygen to hydrogen (1σ uncertainties). If this reflects the global water abundance, the result suggests that the planetesimals that formed Jupiter were unlikely to have been water-rich clathrate hydrates.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Nadir brightness temperatures of perijoves PJ1 to PJ9.
Fig. 2: Limb darkening versus nadir brightness temperature for each channel in the north EZ (0°–4° N).
Fig. 3: Sensitivity study of model parameters.
Fig. 4: Sample of thermal and compositional profiles explored by the Markov Chain Monte Carlo sampler.
Fig. 5: Marginal probability density functions of the ammonia abundance, the water abundance and the ammonia enrichment factor.
Fig. 6: Correlation between water, ammonia and the ammonia enrichment factor.
Fig. 7: Measured brightness temperature and limb-darkening with respect to the best-fitted model.

Data availability

Juno MWR data can be accessed on the Planetary Data System (PDS) Requests for all other data or materials that are presented in the paper but not archived in the PDS should be addressed to C.L.


  1. 1.

    Weidenschilling, S. & Lewis, J. Atmospheric and cloud structures of the Jovian planets. Icarus 20, 465–476 (1973).

    ADS  Article  Google Scholar 

  2. 2.

    Atreya, S. K. & Wong, A.-S. Coupled clouds and chemistry of the giant planets—a case for multiprobes. Space Sci. Rev. 116, 121–136 (2005).

    ADS  Article  Google Scholar 

  3. 3.

    Lewis, J. S. & Prinn, R. G. Jupiter’s clouds: structure and composition. Science 169, 472–473 (1970).

    ADS  Article  Google Scholar 

  4. 4.

    Gierasch, P. J. Jovian meteorology: large-scale moist convection. Icarus 29, 445–454 (1976).

    ADS  Article  Google Scholar 

  5. 5.

    Gierasch, P. J. et al. Observation of moist convection in Jupiter’s atmosphere. Nature 403, 628 (2000).

    ADS  Article  Google Scholar 

  6. 6.

    Wong, M. H. et al. Oxygen and other volatiles in the giant planets and their satellites. Rev. Mineral. Geochem. 68, 219–246 (2008).

    Article  Google Scholar 

  7. 7.

    Young, R. E., Smith, M. A. & Sobeck, C. K. Galileo probe: in situ observations of Jupiter’s atmosphere. Science 272, 837–838 (1996).

    ADS  Article  Google Scholar 

  8. 8.

    Orton, G. S. et al. Characteristics of the Galileo probe entry site from Earth-based remote sensing observations. J. Geophys. Res. Planets 103, 22791–22814 (1998).

    ADS  Article  Google Scholar 

  9. 9.

    Niemann, H. et al. The composition of the Jovian atmosphere as determined by the Galileo probe mass spectrometer. J. Geophys. Res. Planets 103, 22831–22845 (1998).

    ADS  Article  Google Scholar 

  10. 10.

    Wong, M. H., Mahaffy, P. R., Atreya, S. K., Niemann, H. B. & Owen, T. C. Updated Galileo probe mass spectrometer measurements of carbon, oxygen, nitrogen, and sulfur on Jupiter. Icarus 171, 153–170 (2004).

    ADS  Article  Google Scholar 

  11. 11.

    Showman, A. P. & Ingersoll, A. P. Interpretation of Galileo probe data and implications for Jupiter’s dry downdrafts. Icarus 132, 205–220 (1998).

    ADS  Article  Google Scholar 

  12. 12.

    Owen, T. et al. A low-temperature origin for the planetesimals that formed Jupiter. Nature 402, 269 (1999).

    ADS  Article  Google Scholar 

  13. 13.

    Mousis, O., Lunine, J. I., Madhusudhan, N. & Johnson, T. V. Nebular water depletion as the cause of Jupiter’s low oxygen abundance. Astrophys. J. Lett. 751, L7 (2012).

    ADS  Article  Google Scholar 

  14. 14.

    Gautier, D., Hersant, F., Mousis, O. & Lunine, J. I. Enrichments in volatiles in Jupiter: a new interpretation of the Galileo measurements. Astrophys. J. 550, L227–L230 (2001).

    ADS  Article  Google Scholar 

  15. 15.

    Owen, T. & Encrenaz, T. Element abundances and isotope ratios in the giant planets and Titan. Space Sci. Rev. 106, 121–138 (2003).

    ADS  Article  Google Scholar 

  16. 16.

    Helled, R. & Lunine, J. Measuring Jupiter’s water abundance by Juno: the link between interior and formation models. Mon. Not. R. Astron. Soc. 441, 2273–2279 (2014).

    ADS  Article  Google Scholar 

  17. 17.

    Lunine, J. I. & Hunten, D. M. Moist convection and the abundance of water in the troposphere of Jupiter. Icarus 69, 566–570 (1987).

    ADS  Article  Google Scholar 

  18. 18.

    Li, C. & Ingersoll, A. P. Moist convection in hydrogen atmospheres and the frequency of Saturn’s giant storms. Nat. Geosci. 8, 398–403 (2015).

    ADS  Article  Google Scholar 

  19. 19.

    Janssen, M. A. et al. MWR: microwave radiometer for the Juno mission to Jupiter. Space Sci. Rev. 213, 139–185 (2017).

    ADS  Article  Google Scholar 

  20. 20.

    Li, C. et al. The distribution of ammonia on Jupiter from a preliminary inversion of Juno microwave radiometer data. Geophys. Res. Lett. 44, 5317–5325 (2017).

    ADS  Article  Google Scholar 

  21. 21.

    Brown, S. et al. Prevalent lightning sferics at 600 megahertz near Jupiter’s poles. Nature 558, 87 (2018).

    ADS  Article  Google Scholar 

  22. 22.

    Bolton, S. J. et al. Jupiter’s interior and deep atmosphere: the initial pole-to-pole passes with the Juno spacecraft. Science 356, 821–825 (2017).

    ADS  Article  Google Scholar 

  23. 23.

    Achterberg, R. K., Conrath, B. J. & Gierasch, P. J. Cassini CIRS retrievals of ammonia in Jupiter’s upper troposphere. Icarus 182, 169–180 (2006).

    ADS  Article  Google Scholar 

  24. 24.

    de Pater, I., Sault, R., Butler, B., DeBoer, D. & Wong, M. H. Peering through Jupiter’s clouds with radio spectral imaging. Science 352, 1198–1201 (2016).

    ADS  Article  Google Scholar 

  25. 25.

    Li, C. & Chen, X. Simulating Nonhydrostatic Atmospheres on Planets (SNAP): formulation, validation, and application to the Jovian atmosphere. Astrophys. J. Suppl. Ser. 240, 37 (2019).

    ADS  Article  Google Scholar 

  26. 26.

    Lindal, G. F. et al. The atmosphere of Jupiter: an analysis of the Voyager radio occultation measurements. J. Geophys. Res. Space Phys. 86, 8721–8727 (1981).

    ADS  Article  Google Scholar 

  27. 27.

    Bellotti, A., Steffes, P. G. & Chinsomboon, G. Corrigendum to “Laboratory measurements of the 5-20 cm wavelength opacity of ammonia, water vapor, and methane under simulated conditions for the deep jovian atmosphere” [Icarus 280 (2016) 255–267]. Icarus 284, 491–492 (2017).

    ADS  Article  Google Scholar 

  28. 28.

    Asplund, M., Grevesse, N., Sauval, A. J. & Scott, P. The chemical composition of the Sun. Ann. Rev. Astron. Astrophys. 47, 481–522 (2009).

    ADS  Article  Google Scholar 

  29. 29.

    Atreya, S. K. et al. in Saturn in the 21st Century Vol. 20, 5–43 (eds Baines, K. H. et al.) (Cambridge Univ. Press, 2019).

  30. 30.

    Folkner, W. M., Woo, R. & Nandi, S. Ammonia abundance in Jupiter’s atmosphere derived from the attenuation of the Galileo probe’s radio signal. J. Geophys. Res. Planets 103, 22847–22855 (1998).

    ADS  Article  Google Scholar 

  31. 31.

    de Pater, I. et al. Jupiter’s ammonia distribution derived from VLA maps at 3–37 GHz. Icarus 322, 168–191 (2019).

    ADS  Article  Google Scholar 

  32. 32.

    Bjoraker, G. L. et al. The gas composition and deep cloud structure of Jupiter’s Great Red Spot. Astron. J. 156, 101 (2018).

    ADS  Article  Google Scholar 

  33. 33.

    Leconte, J., Selsis, F., Hersant, F. & Guillot, T. Condensation-inhibited convection in hydrogen-rich atmospheres—stability against double-diffusive processes and thermal profiles for Jupiter, Saturn, Uranus, and Neptune. Astron. Astrophys. 598, A98 (2017).

    ADS  Article  Google Scholar 

  34. 34.

    Friedson, A. J. & Gonzales, E. J. Inhibition of ordinary and diffusive convection in the water condensation zone of the ice giants and implications for their thermal evolution. Icarus 297, 160–178 (2017).

    ADS  Article  Google Scholar 

  35. 35.

    Lodders, K. Jupiter formed with more tar than ice. Astrophys. J. 611, 587–597 (2004).

    ADS  Article  Google Scholar 

  36. 36.

    Ingersoll, A. P., Kanamori, H. & Dowling, T. E. Atmospheric gravity waves from the impact of comet Shoemaker-Levy 9 with Jupiter. Geophys. Res. Lett. 21, 1083–1086 (1994).

    ADS  Article  Google Scholar 

  37. 37.

    Allison, M. Planetary waves in Jupiter’s equatorial atmosphere. Icarus 83, 282–307 (1990).

    ADS  Article  Google Scholar 

  38. 38.

    Fletcher, L. N. et al. Retrievals of atmospheric variables on the gas giants from ground-based mid-infrared imaging. Icarus 200, 154–175 (2009).

    ADS  Article  Google Scholar 

  39. 39.

    Goodman, J. & Weare, J. Ensemble samplers with affine invariance. Commun. Appl. Math. Comput. Sci. 5, 65–80 (2010).

    MathSciNet  Article  Google Scholar 

  40. 40.

    Li, C., Ingersoll, A. P. & Oyafuso, F. Moist adiabats with multiple condensing species: a new theory with application to giant-planet atmospheres. J. Atmos. Sci. 75, 1063–1072 (2018).

    ADS  Article  Google Scholar 

Download references


The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The Juno mission and the team members at the Jet Propulsion Laboratory were supported by NASA grant NNN12AA01C. T.G. acknowledges support from CNRS. We thank all Juno team members for the collaborative efforts.

Author information




C.L. developed the inversion software and performed the data analysis. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Cheng Li.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

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

Extended data

Extended Data Fig. 1 Limb-darkening error of the fitting using a three-parameter formula.

Histogram of the difference between the limb-darkening at 45° calculated using equation (4)—R(fit)—and using a radiative transfer model— R(model)—for a wide range of model atmospheres.

Extended Data Fig. 2 Brightness temperature error of the fitting using a three-parameter formula.

Histogram of the percentage difference between the brightness temperature calculated using equation (4)—\(T_{\mathrm{B}}^{\left( {{\mathrm{fit}}} \right)}\)—and using a radiative transfer model—\(T_{\mathrm{B}}^{\left( {{\mathrm{model}}} \right)}\)—over a wide range of model atmospheres.

Extended Data Fig. 3 Spacity pattern of the error covariance matrix.

Sparsity pattern of the covariance matrix of X* in equation (6) (10 GHz). The coefficients are aligned sequentially from a(ϕ) to b(ϕ) to c(ϕ). The dark region indicates that the covariance is large.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Li, C., Ingersoll, A., Bolton, S. et al. The water abundance in Jupiter’s equatorial zone. Nat Astron 4, 609–616 (2020).

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