1. Deep winds beneath Saturn’s upper clouds from a seasonal long-lived planetary-scale storm
- Author
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Sánchez-Lavega, A., del Río-Gaztelurrutia, T., Hueso, R., Gómez-Forrellad, J. M., Sanz-Requena, J. F., Legarreta, J., García-Melendo, E., Colas, François, Lecacheux, Jean, Fletcher, L. N., Barrado y Navascués, D., Parker, D., International Outer Planet Watch Team, The, Departamento de Fisica Aplicada [Bilbao], Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Fundació Privada Observatori Esteve Duran, Universidad europea Miguel de Cervantes (UEMC), Departamento de Ingenieria de Sistemas y Automatica [Bilbao], Institut de Ciencies de l'Espai [Barcelona] (ICE-CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford, Centro Astronómico Hispano Alemán, Observatorio de Calar Alto (CAHA), Association of Lunar and Planetary Observers (ALPO), The International Outer Planet Watch Team (IOPW), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), University of Oxford [Oxford], Universidad del Pais Vasco / Euskal Herriko Unibertsitatea ( UPV/EHU ), Universidad europea Miguel de Cervantes, Institut de Ciencies de l'Espai [Barcelona] ( ICE-CSIC ), Consejo Superior de Investigaciones Científicas [Spain] ( CSIC ), Institut de Mécanique Céleste et de Calcul des Ephémérides ( IMCCE ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université de Lille-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] ( AOPP ), Observatorio de Calar Alto, Centro Astronómico Hispano Alemán, Association of Lunar and Planetary Observers ( ALPO ), Association of Lunar and Planetary Observers, and The International Outer Planet Watch Team ( IOPW )
- Subjects
Convection ,Multidisciplinary ,010504 meteorology & atmospheric sciences ,[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,Astronomy ,Physics ,[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,Storm ,Atmospheric sciences ,[ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,01 natural sciences ,Troposphere ,Planetary science ,[ PHYS.ASTR.EP ] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,13. Climate action ,Planet ,0103 physical sciences ,Convective storm detection ,Thunderstorm ,Geology and geophysics ,Planetary sciences ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Great White Spot - Abstract
Six Great White Spot (GWS) events have been observed in the atmosphere of Saturn since 1876. These giant convective storms occur roughly once every Saturnian year (equal to 29.5 Earth years). The sixth GWS erupted in December 2010 and has been the subject of intense observation. Two papers in this issue present the details of some of these observations. Sanchez-Lavega et al. report that the storm developed at northern latitudes in the peak of a weak westward jet during early northern springtime. The storm head moved faster than the jet and triggered a disturbance that circled the planet. Numerical simulations show that Saturn's winds extend without decay deep down into the weather layer. Fischer et al. report that the storm reached a width of 10,000 kilometres within three weeks. Its lightning flash rates are an order of magnitude greater than those seen in previous storms, peaking at more than 10 flashes per second. Convective storms occur regularly in Saturn’s atmosphere1,2,3,4. Huge storms known as Great White Spots, which are ten times larger than the regular storms, are rarer and occur about once per Saturnian year (29.5 Earth years). Current models propose that the outbreak of a Great White Spot is due to moist convection induced by water5,6. However, the generation of the global disturbance and its effect on Saturn’s permanent winds1,7 have hitherto been unconstrained8 by data, because there was insufficient spatial resolution and temporal sampling9,10,11 to infer the dynamics of Saturn’s weather layer (the layer in the troposphere where the cloud forms). Theoretically, it has been suggested that this phenomenon is seasonally controlled5,9,10. Here we report observations of a storm at northern latitudes in the peak of a weak westward jet during the beginning of northern springtime, in accord with the seasonal cycle but earlier than expected. The storm head moved faster than the jet, was active during the two-month observation period, and triggered a planetary-scale disturbance that circled Saturn but did not significantly alter the ambient zonal winds. Numerical simulations of the phenomenon show that, as on Jupiter12, Saturn’s winds extend without decay deep down into the weather layer, at least to the water-cloud base at pressures of 10–12 bar, which is much deeper than solar radiation penetrates.
- Published
- 2011
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