Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion

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Read Full Article (file size: 219005 bytes) Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L22205, doi:10.1029/2005GL023897, 2005 Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion T. Kostiuk NASA Goddard Space Flight Center, Greenbelt, Maryland, USA T. A. Livengood NASA Goddard Space Flight Center, Greenbelt, Maryland, USA T. Hewagama NASA Goddard Space Flight Center, Greenbelt, Maryland, USA G. Sonnabend National Research Council, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA K. E. Fast NASA Goddard Space Flight Center, Greenbelt, Maryland, USA K. Murakawa Subaru Telescope, National Astronomical Observatory of Japan, Hilo, Hawaii, USA A. T. Tokunaga Institute for Astronomy, University of Hawaii, Honolulu, Hawaii, USA J. Annen NASA Goddard Space Flight Center, Greenbelt, Maryland, USA D. Buhl NASA Goddard Space Flight Center, Greenbelt, Maryland, USA F. Schmülling I. Physikalisches Institut, Universität zu Köln, Cologne, Germany Abstract Saturn's satellite, Titan, may have stratospheric winds up to ∼210 m/s, circling Titan in ∼1 terrestrial day compared to its 16-day rotation. Theoretical models explaining such super-rotating winds are not well constrained by observations of Titan or a similar slow rotator, Venus. We report measurements taken in December 2003 of zonal wind near Titan's equatorial region, including the Cassini Huygens probe entry latitude. Super-rotating prograde zonal winds of 190 ± 90 m/s near 220 km altitude are found from Doppler-shifted C₂H₆ gas emission near 12 μm, confirming high wind velocity even near the equator. Stratospheric temperature constraints and ethane abundance (8 ± 3 ppm) also are retrieved. Results are not inconsistent with earlier measurements and with recent Cassini CIRS results, but indicate possible variations between Titan's hemispheres. Differences in east and west C₂H₆ spectral line shapes can be accounted for by different vertical distributions of either C₂H₆ abundance or temperature or by unidentified dynamical effects. Received 23 June 2005; accepted 28 September 2005; published 30 November 2005. Index Terms: 6281 Planetary Sciences: Solar System Objects: Titan; 6297 Planetary Sciences: Solar System Objects: Instruments and techniques; 6207 Planetary Sciences: Solar System Objects: Comparative planetology; 5464 Planetary Sciences: Solid Surface Planets: Remote sensing; 5405 Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060). Read Full Article (file size: 219005 bytes) Cited by Citation: Kostiuk, T., T. A. Livengood, T. Hewagama, G. Sonnabend, K. E. Fast, K. Murakawa, A. T. Tokunaga, J. Annen, D. Buhl, and F. Schmülling (2005), Titan's stratospheric zonal wind, temperature, and ethane abundance a year prior to Huygens insertion, Geophys. Res. Lett., 32, L22205, doi:10.1029/2005GL023897. Copyright 2005 by the American Geophysical Union.

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