Saturn’s Great White Spots are rare planetary-scale storms that have been observed only six times since 18761,2. The most recent Great White Spot appeared in December 2010 and has been studied from both ground-based3,4 and spacecraft observations5,6,7. The storm developed into an enormous disturbance extending over 10,000 km at cloud level3,4,7, emitted intense electrostatic discharges5 over several months, and caused long-standing localized warming in the high stratosphere6,8 of about 60 K. Here we analyse the dynamics of the storm’s head using high-resolution imagery obtained by the Cassini spacecraft on 26 February 2011. We find strong winds with speeds up to 160 m s−1 and organized into a divergent open anticyclone where massive cumulus-like cloud clusters interact with the ambient zonal flow to generate a storm front. The cloud clusters evolved over a timescale of hours, with cloud tops reaching 44 km above the undisturbed environment. Simulations using a general circulation model, which includes Saturn’s zonal winds, reproduce the observations when a persistent heat source is introduced, causing a high-pressure anomaly. We conclude that the complex phenomenology of a mature Great White Spot represents a natural response of the saturnian atmosphere to severe sustained convection in a sheared background flow.
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We gratefully acknowledge the work of the Cassini ISS team that allowed these data to be obtained. We are grateful to J. Guerrero for installing EPIC at the ICE computer facilities. This research also made use of the computing facilities at CESCA in Barcelona with the help of the Spanish MICINN-MEC. This work was supported by the Spanish MICINN project AYA2009-10701 and AYA2012-36666 with FEDER support, Grupos Gobierno Vasco IT-464-07 and UPV/EHU UFI11/55.
The authors declare no competing financial interests.
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García-Melendo, E., Hueso, R., Sánchez-Lavega, A. et al. Atmospheric dynamics of Saturn’s 2010 giant storm. Nature Geosci 6, 525–529 (2013). https://doi.org/10.1038/ngeo1860
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