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The Voyager 1 and 2 Ultraviolet Spectrometer (UVS) solar and stellaroccultation dataset represents one of the primary, pre-Cassini sources ofinformation that we have on the neutral upper atmosphere of Saturn. Despite itsimportance, however, the full set of occultations has never received aconsistent, nor complete, analysis, and the results derived from the initialanalyses over thirty years ago left questions about the temperature and densityprofiles unanswered. We have reanalyzed all six of the UVS occultations (threesolar and three stellar) to provide an up-to-date, pre-Cassini view of Saturn'supper atmosphere. From the Voyager UVS data, we have determined verticalprofiles for H2, H, CH4, C2H2 , C2H4, and C2H6, as well as temperature. Ouranalysis also provides explanations for the two different thermospherictemperatures derived in earlier analyses (400-450 K versus 800 K) and for theunusual shape of the total density profile noted by Hubbard et al. (1997).Aside from inverting the occultation data to retrieve densities andtemperatures, we have investigated the atmospheric structure through a seriesof photochemical models to infer the strength of atmospheric mixing and otherphysical and chemical properties of Saturn's mesopause region during theVoyager flybys. We find that the data exhibit considerable variability in thevertical profiles for methane, suggesting variations in vertical winds or theeddy diffusion coefficient as a function of latitude and/or time in Saturn'supper atmosphere. The results of our reanalysis will provide a useful baselinefor interpreting new data from Cassini, particularly in the context of changeover the past three decades.

Saturn's upper atmosphere during the Voyager era: Reanalysis and modeling of the UVS occultations