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Long-term evolution of the aerosol debris cloud produced by the 2009 impact on Jupiter |
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| Authors: | A Sánchez-Lavega GS Orton R Hueso LN Fletcher E García-Melendo I de Pater HB Hammel A Simon-Miller F Marchis O Mousis J García-Rojas M Cecconi K Noll S Pedraz P Kalas W Golisch P Sears V Reddy R Binzel W Grundy J Emery A Rivkin C Thomas D Trilling K Bjorkman AJ Burgasser H Campins TM Sato Y Kasaba J Ziffer R Mirzoyan H Bouy |
| Institution: | a Departamento de Física Aplicada I, Escuela T. Superior de Ingeniería, Universidad del País Vasco, Bilbao, Spain b MS 169-237, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA c Atmospheric, Oceanic & Planetary Physics, Department of Physics University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK d Fundació Privada Observatori Esteve Duran, Montseny 46, 08553 Seva, Spain e Astronomy Department, 601 Campbell Hall, University of California, Berkeley, CA 94720, USA f Space Science Institute, 4750 Walnut Avenue, Suite 205, Boulder, CO 80301, USA g NASA Goddard Space Flight Center Greenbelt, MD 20771, USA h Departamento de Matemática Aplicada, E.U.I.T.I., Universidad del País Vasco, Bilbao, Spain i Carl Sagan Center at the SETI Institute, 189 Bernardo Av., Mountain View, CA 94043, USA j Observatoire de Besançon, Institut UTINAM, UMR/CNRS 6213, 41 bis Avenue de l’Observatoire, BP 1615, 25010 Besançon Cedex, France k Instituto de Astrofísica de Andalucía, C.S.I.C., Granada, Spain l Instituto de Astrofísica de Canarias, La Laguna (Tenerife), Spain m Departamento de Astrofísica, Universidad de La Laguna., E-38205 La Laguna, Tenerife, Spain n Fundación Galileo Galilei - INAF, Rambla José Ana Férnandez Pérez, 738712 San Antonio de Breña Baja, La Palma, Spain o Center for Space Physics, Boston University, 957 Commonwealth Ave., Boston, MA 02215, USA p Space Science Institute, 72 Sarah Bishop Rd., Ridgefield, CT 06877, USA q Calar Alto Obs Centro Astronómico Hispano Alemán, Calle Jesús Durbán Remón 2-2, 04004 Almeria, Spain r Acquerra Pty. Ltd., 82 Merryville Drive, Murrumbateman NSW, Australia s Institute for Astronomy, University of Hawaii, 640 N. Aohoku Pl., Hilo, HI 96720, USA t Dept. of Space Studies, Clifford Hall, Univ. N. Dakota, Room 520, 4949 University Ave. Stop 9008, Grand Forks, ND 58202-9008, USA u Astrophysics Dept., American Museum of Natural History, Central Park West & 79th St., New York, NY 10024-5192, USA v MS 54-410, Dept. of Earth & Planetary Sci., Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139-4301, USA w Lowell Observatory, 1400 W. Mars Hill Rd., Flagstaff, AZ 86001, USA x 306 Earth & Planetary Sciences Bldg, 1412 Circle Dr., Univ. Tennessee, Knoxville, TN 37996-1410, USA y NP3-E169, Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA z Dept. of Physics & Astronomy, Northern Arizona University, P.O. Box 6010, Flagstaff, AZ 86011, USA aa Dept. of Physics & Astronomy, MS #111, Univ. of Toledo, Toledo, OH 43606-3390, USA ab Dept. of Physics, Mail Code 0424, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA ac Dept. of Physics, University of Central Florida, Orlando, FL 32816-2385, USA ad Tohoku University, Aramaki-Aza-Aoba 6-3, Aoba-ku, Sendai, 980-8578, Japan ae Univ. Southern Maine, 96 Falmouth Street, P.O. Box 9300, Portland, ME 04104-9300, USA af Glendale Community College, 1500 N. Verdugo Rd., Glendale, CA 91208, USA ag Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550, USA ah Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA ai Centro de Astrobiologia (INTA-CSIC), P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain |
| Abstract: | We present a study of the long-term evolution of the cloud of aerosols produced in the atmosphere of Jupiter by the impact of an object on 19 July 2009 (Sánchez-Lavega, A. et al. 2010]. Astrophys. J. 715, L155-L159). The work is based on images obtained during 5 months from the impact to 31 December 2009 taken in visible continuum wavelengths and from 20 July 2009 to 28 May 2010 taken in near-infrared deep hydrogen-methane absorption bands at 2.1-2.3 μm. The impact cloud expanded zonally from ∼5000 km (July 19) to 225,000 km (29 October, about 180° in longitude), remaining meridionally localized within a latitude band from 53.5°S to 61.5°S planetographic latitude. During the first two months after its formation the site showed heterogeneous structure with 500-1000 km sized embedded spots. Later the reflectivity of the debris field became more homogeneous due to clump mergers. The cloud was mainly dispersed in longitude by the dominant zonal winds and their meridional shear, during the initial stages, localized motions may have been induced by thermal perturbation caused by the impact’s energy deposition. The tracking of individual spots within the impact cloud shows that the westward jet at 56.5°S latitude increases its eastward velocity with altitude above the tropopause by 5-10 m s−1. The corresponding vertical wind shear is low, about 1 m s−1 per scale height in agreement with previous thermal wind estimations. We found evidence for discrete localized meridional motions with speeds of 1-2 m s−1. Two numerical models are used to simulate the observed cloud dispersion. One is a pure advection of the aerosols by the winds and their shears. The other uses the EPIC code, a nonlinear calculation of the evolution of the potential vorticity field generated by a heat pulse that simulates the impact. Both models reproduce the observed global structure of the cloud and the dominant zonal dispersion of the aerosols, but not the details of the cloud morphology. The reflectivity of the impact cloud decreased exponentially with a characteristic timescale of 15 days; we can explain this behavior with a radiative transfer model of the cloud optical depth coupled to an advection model of the cloud dispersion by the wind shears. The expected sedimentation time in the stratosphere (altitude levels 5-100 mbar) for the small aerosol particles forming the cloud is 45-200 days, thus aerosols were removed vertically over the long term following their zonal dispersion. No evidence of the cloud was detected 10 months after the impact. |
| Keywords: | Atmospheres Dynamics Jupiter Atmosphere Impact processes |
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