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[18.15] The state of Saturn's stratosphere in 2002: Latitudinal variations of temperature, winds, and abundances of C₂H₂ and C₂H₆ between 10 and 0.01 mbar.

T.K. Greathouse (Lunar and Planetary Institute), J. H. Lacy (University of Texas at Austin), J. I. Moses (Lunar and Planetary Institute), B. Bézard (Observatoire de Paris), C. A. Griffith (Lunar and Planetary Laboratory), M. J. Richter (University of California, Davis)

We present a detailed study of the latitudinal dependence of stratospheric temperature, zonal winds, and abundances of C₂H₂ and C₂H₆ near Saturn's southern summer solstice, L_S~270^o. Using TEXES, the Texas Echelon cross-dispersed Echelle Spectrograph, mounted on NASA's IRTF we retrieved high spectral resolution mid-infrared observations along Saturn's central meridian between the equator and south pole. Line-by-line radiative transfer modeling of the CH₄ emission observations centered at 1230 cm^-1 indicates a ~ 9 K increase in temperature from the equator to the south pole between 10 and 0.01 mbar along with smaller scale temperature variations superimposed on this trend. Using the derived temperature information in conjunction with the thermal wind equation, we infer Saturn's stratospheric zonal winds, u(p) - u(10 mbar), for pressures between 10 and 0.01 mbar. Radiative transfer modeling of the observed spectra at 730 and 820 cm^-1, using the above derived temperature profiles, allowed us to derive the latitudinal abundance variations of C₂H₂ and C₂H₆, respectively. We discuss the implications these abundance variations have on our understanding of Saturn's stratospheric circulation.

This work has been supported by USRA grant 8500-98-008, NSF grant AST 0205518, and the LPI under contract with NASA.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.