Observations of CH4, C2H6, and C2H2 in the Stratosphere of Jupiter

We have performed high-resolution mid-infrared spectral observations of CH4 (8.14-mu m), C2H6 (12.16-mu m), and C2H2 (13.45-mu m) on Jupiter. The emission features observed probe the stratosphere of the planet. They provide information on the carbon-based photochemical processes taking place in that region of the atmosphere. The observations were performed using our cryogenic echelle spectrometer CELESTE, in conjunction with the McMath-Pierce 1.5-m solar telescope (NSO at KPNO) on various occasions between November 1994 and February 1995. We used the methane observations, along with an assumed molecular volume mixing ratio, to modify the average temperature profile derived from the Voyager Radio Occultation Experiment for pressure levels between 1 and 10 mbar. This temperature profile was then used in conjunction with height-dependent molecular mixing ratios derived from recent photochemical models to determine global abundances for ethane and acetylene. The resulting mixing ratios at 5 mbar, the pressure level in the atmosphere to which our observations are most sensitive, are 4.5+/-0.2x10(-6) for C2H6 and 3.9+/-0.4x10(-8) for C2H2.