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N. J. Chanover, T. Temma (New Mexico State Univ.), G. Bjoraker (NASA/GSFC), T. Hewagama (U. Maryland)
Near-infrared spectra of Saturn were acquired at the NASA Infrared Telescope Facility using SpeX on 06-09 January 2002. Using the long wavelength cross-dispersed mode, spectra between 2.7-5.5 microns were recorded simultaneously at a spectral resolution R ~ 2000. With the slit of the spectrograph aligned parallel to Saturn's rotation axis, spectra were extracted for different latitude bands on Saturn to enable a comparison of the trace species mixing ratios as a function of latitude. Synthetic infrared spectra were generated using the COmposition and Dynamics Analysis Tools (CODAT) package for comparison with the observational data. CODAT assumes a multi-layer, plane-parallel geometry, and includes an atmospheric molecular line-by-line radiative transfer modeling engine. It incorporates a robust, non-linear model parameter optimization algorithm to constrain the derivation of model atmospheres consistent with observed spectra, and to develop statistically valid estimations of parameter uncertainties.
We compare observed and modeled spectra in an effort to characterize any spatial variations in Saturn's trace constituents, which could be indicative of localized or regional dynamical processes. We vary the mixing ratios of ammonia and phosphine, as well as the pressure level boundaries of the absorbing region. Our exploration of this parameter space, as well as mixing ratios and atmospheric structure that best fit the observed structure, will be discussed.
This work was supported by NASA under grant NAG5-7904.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.