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SEASONAL CHANGES IN TITAN'S POLAR TRACE GAS ABUNDANCE OBSERVED BY CASSINI

ASTROPHYSICAL JOURNAL LETTERS 724:1 (2010) L84-L89

Authors:

NA Teanby, PGJ Irwin, R de Kok, CA Nixon
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Structure and dynamics of the Martian lower and middle atmosphere as observed by the Mars Climate Sounder: Seasonal variations in zonal mean temperature, dust, and water ice aerosols

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS 115 (2010) ARTN E12016

Authors:

DJ McCleese, NG Heavens, JT Schofield, WA Abdou, JL Bandfield, SB Calcutt, PGJ Irwin, DM Kass, A Kleinbohl, SR Lewis, DA Paige, PL Read, MI Richardson, JH Shirley, FW Taylor, N Teanby, RW Zurek
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System study of EPICS, the exoplanets imager for the E-ELT

ADAPTIVE OPTICS SYSTEMS II 7736 (2010) ARTN 77361N

Authors:

Christophe Verinaud, Markus Kasper, Jean-Luc Beuzit, Raffaele G Gratton, Dino Mesa, Emmanuel Aller-Carpentier, Enrico Fedrigo, Lyu Abe, Pierre Baudoz, Anthony Boccaletti, Mariangela Bonavita, Kjetil Dohlen, Norbert Hubin, Florian Kerber, Visa Korkiakoski, Jacopo Antichi, Patrice Martinez, Patrick Rabou, Ronald Roelfsema, Hans Martin Schmid, Niranjan Thatte, Graeme Salter, Matthias Tecza, Lars Venema, Hiddo Hanenburg, Rieks Jager, Natalia Yaitskova, Olivier Preis, Melanie Orecchia, Eric Stadler
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Upper limits for undetected trace species in the stratosphere of Titan.

Faraday Discuss 147 (2010) 65-81

Authors:

Conor A Nixon, Richard K Achterberg, Nicholas A Teanby, Patrick GJ Irwin, Jean-Marie Flaud, Isabelle Kleiner, Alix Dehayem-Kamadjeu, Linda R Brown, Robert L Sams, Bruno Bézard, Athena Coustenis, Todd M Ansty, Andrei Mamoutkine, Sandrine Vinatier, Gordon L Bjoraker, Donald E Jennings, Paul N Romani, F Michael Flasar

Abstract:

In this paper we describe the first quantitative search for several molecules in Titan's stratosphere in Cassini CIRS infrared spectra. These are: ammonia (NH3), methanol (CH3OH), formaldehyde (H2CO), and acetonitrile (CH3CN), all of which are predicted by photochemical models but only the last of which has been observed, and not in the infrared. We find non-detections in all cases, but derive upper limits on the abundances from low-noise observations at 25 degrees S and 75 degrees N. Comparing these constraints to model predictions, we conclude that CIRS is highly unlikely to see NH3 or CH3OH emissions. However, CH3CN and H2CO are closer to CIRS detectability, and we suggest ways in which the sensitivity threshold may be lowered towards this goal.
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Small-scale composition and haze layering in Titan's polar vortex

Icarus 204:2 (2009) 645-657

Authors:

NA Teanby, R de Kok, PGJ Irwin

Abstract:

Fine scale layering of haze and composition in Titan's stratosphere and mesosphere was investigated using visible/UV images from Cassini's Imaging Science Sub-system (ISS) and IR spectra from Cassini's Composite Infra-Red Spectrometer (CIRS). Both ISS and CIRS independently show fine layered structures in haze and composition, respectively, in the 150-450 km altitude range with a preferred vertical wavelength of around 50 km. Layers are most pronounced around the north polar winter vortex, although some weaker layers do exist at more southerly latitudes. The amplitude of composition layers in each trace gas profile is proportional to the relative enrichment of that species in the winter polar vortex compared to equatorial latitudes. As enrichment is caused by polar subsidence, this suggests a dynamical origin. We propose that the polar layers are caused by cross-latitude advection across the vortex boundary. This is analogous to processes that lead to ozone laminae formation around Earth's polar vortices. © 2009 Elsevier Inc. All rights reserved.
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