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A complex storm system in Saturn’s north polar atmosphere in 2018


Saturn’s convective storms usually fall in two categories. One consists of mid-sized storms 2,000 km wide, appearing as irregular bright cloud systems that evolve rapidly, on scales of a few days. The other includes the Great White Spots, planetary-scale giant storms ten times larger than the mid-sized ones, which disturb a full latitude band, enduring several months, and have been observed only seven times since 1876. Here we report a new intermediate type, observed in 2018 in the north polar region. Four large storms with east–west lengths 4,000–8,000 km (the first one lasting longer than 200 days) formed sequentially in close latitudes, experiencing mutual encounters and leading to zonal disturbances affecting a full latitude band 8,000 km wide, during at least eight months. Dynamical simulations indicate that each storm required energies around ten times larger than mid-sized storms but 100 times smaller than those necessary for a Great White Spot. This event occurred at about the same latitude and season as the Great White Spot in 1960, in close correspondence with the cycle of approximately 60 years hypothesized for equatorial Great White Spots.

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Fig. 1: The 2018 complex north polar storm system and disturbances.
Fig. 2: Storm motions from 29 March to 29 October 2018.
Fig. 3: Convective onset in a compact cyclone.
Fig. 4: Vertical cloud structure and particle imaginary refractive index.
Fig. 5: Numerical simulations of the disturbances generated by the storm outbreaks.
Fig. 6: Seasonal insolation at the top of Saturn’s atmosphere and convective events.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author on reasonable request. This work relies on images that can be downloaded from the following sources (see Supplementary Information for further details): ALPO-Japan (; PVOL2 database (; HST-OPAL programme (; and Cassini ISS images at NASA Planetary Data System ( PlanetCam images are available from the corresponding author.

Code availability

The shallow water model code30 is available from E.G.-M. ( on request. The radiative transfer code NEMESIS ( is available on request from P.Irwin ( The EPIC numerical model31 is an open-code funded by NASA; see details:


  1. 1.

    Sromovsky, L. A. et al. Voyager 2 observations of Saturn’s northern mid-latitude cloud features: morphology, motions, and evolution. J. Geophys. Res. 88, 8650–8666 (1983).

    ADS  Article  Google Scholar 

  2. 2.

    Ingersoll, A. P., Beebe, R. F., Conrath, B. J. & Hunt, G. E. in Saturn (eds Gehrels, T. & Matthews, M. S.) 195–238 (Univ. Arizona Press, 1984).

  3. 3.

    Sánchez-Lavega, A., Rojas, J. F. & Sada, P. V. Saturn’s zonal winds at cloud level. Icarus 147, 405–420 (2000).

    ADS  Article  Google Scholar 

  4. 4.

    Sánchez-Lavega, A. et al. A strong decrease in Saturn’s equatorial jet at cloud level. Nature 423, 623–625 (2003).

    ADS  Article  Google Scholar 

  5. 5.

    Sánchez-Lavega, A. et al. Saturn’s cloud morphology and zonal winds before the cassini encounter. Icarus 170, 519–523 (2004).

    ADS  Article  Google Scholar 

  6. 6.

    Sánchez-Lavega, A. et al. Deep winds beneath Saturn’s upper clouds from a seasonal long-lived planetary-scale storm. Nature 475, 71–74 (2011).

    ADS  Article  Google Scholar 

  7. 7.

    Porco, C. C. et al. Cassini imaging science: Initial results on Saturn’s atmosphere. Science 307, 1243–1247 (2005).

    ADS  Article  Google Scholar 

  8. 8.

    Sayanagi, K. M. et al. Dynamics of Saturn’s great storm of 2010-2011 from Cassini ISS and RPWS. Icarus 223, 460–478 (2013).

    ADS  Article  Google Scholar 

  9. 9.

    Sánchez-Lavega, A. et al. in Saturn in the 21st Century (eds Baines, K. H. et al.) 377–416 (Cambridge Univ. Press, 2019).

  10. 10.

    Dyudina, U. A. et al. Lightning storms on Saturn observed by Cassini ISS and RPWS during 2004-2006. Icarus 190, 545–555 (2007).

    ADS  Article  Google Scholar 

  11. 11.

    Dyudina, U. A. et al. Detection of visible lightning on Saturn. Geophys. Res. Lett. 37, L09205 (2010).

    ADS  Article  Google Scholar 

  12. 12.

    Fischer, G. et al. A giant thunderstorm on Saturn. Nature 475, 75–77 (2011).

    ADS  Article  Google Scholar 

  13. 13.

    Sánchez-Lavega, A. & Battaner, E. The nature of Saturn’s great white spots. Astron. Astrophys. 185, 315–326 (1987).

    ADS  Google Scholar 

  14. 14.

    Hueso, R. & Sánchez-Lavega, A. A three-dimensional model of moist convection for the giant planets II: Saturn’s water and ammonia moist convective storms. Icarus 172, 255–271 (2004).

    ADS  Article  Google Scholar 

  15. 15.

    Del Genio, A. D. et al. in Saturn after Cassini-Huygens (eds Dougherty, M., Esposito, L. & Krimigis, T.) 113–159 (Springer, 2009).

  16. 16.

    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 

  17. 17.

    Hueso, R. et al. The Planetary Virtual Observatory and Laboratory (PVOL) and its integration into the Virtual European Solar and Planetary Access (VESPA). Planet. Space Sci. 150, 22–35 (2018).

    ADS  Article  Google Scholar 

  18. 18.

    Mendikoa, I. et al. PlanetCam UPV/EHU: A two channel lucky imaging camera for Solar System studies in the spectral range 0.38–1.7 μm. Pub. Astron. Soc. Pacific 128, 035002 (2016).

    ADS  Article  Google Scholar 

  19. 19.

    Simon, A. A., Wong, M. H. & Orton, G. S. First Results from the Hubble OPAL program: Jupiter in 2015. Astrophys. J. 812, 51S (2015).

    ADS  Article  Google Scholar 

  20. 20.

    García-Melendo, E. et al. Saturn’s zonal wind profile in 2004–2009 from Cassini ISS images and its long-term variability. Icarus 215, 62–74 (2011).

    ADS  Article  Google Scholar 

  21. 21.

    Archinal, B. A. et al. Report of the IAU working group on cartographic coordinates and rotation elements: 2015. Celest. Mech. Dyn. Astr. 130, 22 (2018).

    ADS  MathSciNet  Article  Google Scholar 

  22. 22.

    del Río-Gaztelurrutia, T. et al. A planetary-scale disturbance in a long living three vortex coupled system in Saturn’s atmosphere. Icarus 302, 499–513 (2018).

    ADS  Article  Google Scholar 

  23. 23.

    Fletcher, L. N. et al. Moist convection and the 2010–2011 revival of Jupiter’s South Equatorial Belt. Icarus 286, 94–117 (2017).

    ADS  Article  Google Scholar 

  24. 24.

    Sánchez-Lavega, A. An Introduction to Planetary Atmospheres 118–121, 376–377 (CRC, 2011).

  25. 25.

    Irwin, P. G. J. et al. The NEMESIS planetary atmosphere radiative transfer and retrieval tool. J. Quant. Spectrosc. Radiat. Transf. 109, 1136–1150 (2008).

    ADS  Article  Google Scholar 

  26. 26.

    Sanz-Requena, J. F. et al. Haze and cloud structure of Saturn’s North Pole and Hexagon Wave from Cassini/ISS imaging. Icarus 305, 284–300 (2018).

    ADS  Article  Google Scholar 

  27. 27.

    Sánchez-Lavega, A., Pérez-Hoyos, S. & Hueso, R. Condensate clouds in planetary atmospheres: a useful application of the Clausius–Clapeyron equation. Am. J. Phys. 72, 767–774 (2004).

    ADS  Article  Google Scholar 

  28. 28.

    West, R. A., Baines, K. H., Karkoschka, E. & Sánchez-Lavega, A. in Saturn after Cassini-Huygens (eds Dougherty, M., Esposito, L. & Krimigis, T.) 161–179 (Springer, 2009).

  29. 29.

    Sromovsky, L. A., Baines, K. H. & Fry, P. M. Models of bright storm clouds and related dark ovals in Saturn’s Storm Alley as constrained by 2008 Cassini/VIMS spectra. Icarus 302, 360–385 (2018).

    ADS  Article  Google Scholar 

  30. 30.

    García-Melendo, E. & Sánchez-Lavega, A. Shallow water simulations of Saturn’s giant storms at different latitudes. Icarus 286, 241–260 (2017).

    ADS  Article  Google Scholar 

  31. 31.

    Dowling, T. E. The Explicit Planetary Isentropic-Coordinate (EPIC) atmospheric model. Icarus 132, 221–238 (1998).

    ADS  Article  Google Scholar 

  32. 32.

    García-Melendo, E. et al. Atmospheric dynamics of Saturn’s 2010 giant storm. Nat. Geosci. 6, 525–529 (2013).

    ADS  Article  Google Scholar 

  33. 33.

    Sánchez-Lavega, A. Saturn’s great white spots. Chaos 4, 341–353 (1994).

    ADS  Article  Google Scholar 

  34. 34.

    Dollfus, A. Mouvements dans l’atmosphère de Saturne en 1960. Observations coordonées par l’Union Astronomiwur Internationale. Icarus 2, 109–114 (1963).

    ADS  Article  Google Scholar 

  35. 35.

    Sánchez Lavega, A. et al. Large-scale storms in Saturn’s atmosphere during 1994. Science 271, 631–634 (1996).

    ADS  Article  Google Scholar 

  36. 36.

    Norwood, P. et al. Giant planet observations with the james webb space telescope. Pub. Astron. Soc. Pac. 128, 018005 (2016).

    ADS  Article  Google Scholar 

  37. 37.

    Mousis, O. et al. Instrumental methods for professional and amateur collaborations in planetary astronomy. Exp. Astron. 38, 91–191 (2014).

    ADS  Article  Google Scholar 

  38. 38.

    Hahn, G. & Jacquesson, M. WinJUPOS. Homepage Grischa Hahn (2019).

  39. 39.

    Porco, C. C. et al. Cassini imaging science: instrument characteristics and anticipated scientific investigations at Saturn. Space Sci. Rev. 115, 363–497 (2004).

    ADS  Article  Google Scholar 

  40. 40.

    Hueso, R. et al. The Planetary Laboratory for Image Analysis (PLIA). Adv. Space Res. 46, 1120–1138 (2010).

    ADS  Article  Google Scholar 

  41. 41.

    Dressel, L. Wide Field Camera 3 Instrument Handbook, Version 10.0 (Space Telescope Science Institute, 2018).

  42. 42.

    Fletcher, L. N. et al. Methane and its isotopologues on Saturn from Cassini/CIRS observations. Icarus 199, 351–367 (2009).

    ADS  Article  Google Scholar 

  43. 43.

    Lindal, G. F. et al. The atmosphere of Saturn – an analysis of the Voyager radio occultation measurements. Astron. J. 90, 1136–1146 (1985).

    ADS  Article  Google Scholar 

  44. 44.

    Pérez-Hoyos, S. et al. Saturn’s tropospheric particles phase function and spatial distribution from Cassini ISS 2010-11 observations. Icarus 277, 1–18 (2016).

    ADS  Article  Google Scholar 

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This work has been supported by the Spanish project AYA2015-65041-P (MINECO/FEDER, UE) and Grupos Gobierno Vasco IT-366-19. A list of the sources for the images used in this paper can be found in the Supplementary Information. This work used data acquired from the NASA/ESA HST Space Telescope, associated with OPAL programme (principal investigator: Simon, GO13937), and archived by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract no. NAS 5-26555. All OPAL maps are available at, and M.H.W. and A.A.S. acknowledge financial support from his programme. M.H.W. through a grant from the Space Telescope Science Institute, which is operated by AURA under NASA contract NAS 5-26555.

Author information




A.S.-L. directed the work, made the features tracking measurements, retrieved the winds and interpreted the results. E.G.-M., M.S. and J.L. performed the shallow water and EPIC numerical simulations. T.d.R.-G. performed the Cassini image analysis of the storm precursor. R.H., J.M.G.-F., T.B., M.D. contributed to the analysis of ground-based observations. J.F.S.-R. and S.P.-H. performed the radiative transfer analysis. A.A.S. and M.H.W. performed the HST observations and helped in their analysis. K.M.S., J.J.B. and J.L.G. mapped and analyzed Cassini ISS images. U.D. and S.E. designed the ISS observation sequences. All authors discussed the results and contributed to preparing the manuscript.

Corresponding authors

Correspondence to A. Sánchez-Lavega or E. García-Melendo.

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The authors declare no competing interests.

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Peer review information Nature Astronomy thanks Cheng Li and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Sánchez-Lavega, A., García-Melendo, E., Legarreta, J. et al. A complex storm system in Saturn’s north polar atmosphere in 2018. Nat Astron 4, 180–187 (2020).

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