A TRANSMISSION SPECTRUM OF TITAN'S NORTH POLAR ATMOSPHERE FROM A SPECULAR REFLECTION OF THE SUN

• Published in: The Astrophysical Journal
• Main Authors: Barnes, Jason, Clark, Roger, Sotin, Christophe, Ádámkovics, Máté, Appéré, Thomas, Rodriguez, Sebastien, Soderblom, Jason, Brown, Robert, Buratti, Bonnie, Baines, Kevin, Le Mouélic, Stéphane, Nicholson, Philip
• Other Authors: University of Idaho Moscow, USA, Planetary Science Institute Tucson (PSI), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Astronomy Berkeley, University of California Berkeley (UC Berkeley), University of California (UC)-University of California (UC), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS), University of Arizona, New York Presbyterian Hospital, Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy Ithaca, Cornell University New York
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: planets and satellites; individual (Titan) -radiative transfer -techniques; spectroscopic; [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]; Arctic; Titan; albedo
• Online Access: https://u-paris.hal.science/hal-03657809; https://u-paris.hal.science/hal-03657809/document; https://u-paris.hal.science/hal-03657809/file/2013.11.ApJ.Barnes.SpecularTransmission.pdf; https://doi.org/10.1088/0004-637x/777/2/161

International audience Cassini/VIMS T85 observations of a solar specular reflection off of Kivu Lacus (87. • 4N 241. • 1E) provide an empirical transmission spectrum of Titan's atmosphere. Because this observation was acquired from short range (33,000 km), its intensity makes it visible within the 2.0, 2.7, and 2.8 μm atmospheric windows in addition to the 5 μm window where all previous specular reflections have been seen. The resulting measurement of the total one-way normal atmospheric optical depth (corresponding to haze scattering plus haze and gas absorption) provides strong empirical constraints on radiative transfer models. Using those models, we find that the total haze column abundance in our observation is 20% higher than the Huygens equatorial value. Ours is the first measurement in the 2-5 μm wavelength range that probes all the way to the surface in Titan's arctic, where the vast majority of surface liquids are located. The specular technique complements other probes of atmospheric properties such as solar occultations and the direct measurements from Huygens. In breaking the degeneracy between surface and atmospheric absorptions, our measured optical depths will help to drive future calculations of deconvolved surface albedo spectra.