Dissipation of Titan's south polar clouds

Nearly all adaptive optics images of Titan taken between December 2001 and November 2004 showed tropospheric clouds located within 30° of the south pole. We report here on a dissipation of Titan's south polar clouds observed in twenty-nine Keck and Gemini images taken between December 2004 and April 2005. The near complete lack of south polar cloud activity during this time, and subsequent resurgence months later at generally higher latitudes, may be the beginning of seasonal change in Titan's weather. The ∼5 month decrease in cloud activity may also have been caused by methane rainout from a large cloud event in October 2004. Understanding the seasonal evolution of Titan's clouds, and of any precipitation associated with them, is essential for interpreting the geological observations of fluid flow features observed over a wide range of Titan latitudes with the Cassini/Huygens spacecraft.

[1]  Dennis L. Matson,et al.  The Huygens Probe: Science, Payload and Mission Overview , 1997 .

[2]  F. Hourdin,et al.  The Latitudinal Distribution of Clouds on Titan , 2006, Science.

[3]  Günter Kargl,et al.  A soft solid surface on Titan as revealed by the Huygens Surface Science Package , 2005, Nature.

[4]  F. Flasar,et al.  Oceans on Titan? , 1983, Science.

[5]  T. Owen,et al.  Transient clouds in Titan's lower atmosphere , 1998, Nature.

[6]  M. W. Evans,et al.  Imaging of Titan from the Cassini spacecraft , 2005, Nature.

[7]  Michael E. Brown,et al.  A large cloud outburst at Titan’s south pole , 2006 .

[8]  Klaus W. Hodapp,et al.  The Gemini Near‐Infrared Imager (NIRI) , 2003 .

[9]  D. Campbell,et al.  Radar Evidence for Liquid Surfaces on Titan , 2003, Science.

[10]  Michael E. Brown,et al.  Statistics of Titan’s South Polar Tropospheric Clouds , 2004 .

[11]  Roberto Orosei,et al.  Cryovolcanic features on Titan's surface as revealed by the Cassini Titan Radar Mapper , 2007 .

[12]  C. McKay,et al.  Titan's Clouds from Gemini and Keck Adaptive Optics Imaging , 2002 .

[13]  C. Sotin,et al.  The Evolution of Titan's Mid-Latitude Clouds , 2005, Science.

[14]  Michael E. Brown,et al.  Discovery of Temperate Latitude Clouds on Titan , 2004 .

[15]  T. Fusco,et al.  Astrophysics Vlt/naco Adaptive Optics Imaging of Titan , 2022 .

[16]  J. Lunine,et al.  Numerical Modeling of Impact Cratering on Titan with Implications for the Age of Titan's Surface , 2005 .

[17]  T. Tokano.  Meteorological assessment of the surface temperatures on Titan: constraints on the surface type , 2005 .

[18]  A. Bouchez,et al.  Direct detection of variable tropospheric clouds near Titan's south pole , 2002, Nature.

[19]  J. Lunine,et al.  Ethane Ocean on Titan , 1983, Science.

[20]  Jean-Pierre Lebreton,et al.  An overview of the descent and landing of the Huygens probe on Titan , 2005, Nature.

[21]  M. Allen,et al.  Photochemistry of the atmosphere of Titan: comparison between model and observations. , 1984, The Astrophysical journal. Supplement series.

[22]  J. L. Hall,et al.  Detection of daily clouds on Titan. , 2000, Science.

[23]  Glen Herriot,et al.  Progress on Altair: the Gemini North adaptive optics system , 2000, Astronomical Telescopes and Instrumentation.

[24]  Claire E. Max,et al.  Speckle Imaging of Titan at 2 microns: Surface Albedo,Haze Optical Depth, and Tropospheric Clouds 1996-1998 , 2004 .

[25]  Mark T. Lemmon,et al.  Titan's Surface, Revealed by HST Imaging , 1996 .

[26]  R. West,et al.  No oceans on Titan from the absence of a near-infrared specular reflection , 2005, Nature.

[27]  D. S. Acton,et al.  First Light Adaptive Optics Images from the Keck II Telescope: A New Era of High Angular Resolution Imagery , 2000 .

[28]  M. McElwain,et al.  OSIRIS: AO-assisted integral-field spectroscopy at the Keck Observatory , 2006 .

[29]  A. Bouchez,et al.  Geographic Control of Titan's Mid-Latitude Clouds , 2005, Science.