Mid-IR Observations of Ethylene on Jupiter

Ethylene is an important species to our understanding of hydrocarbon photochemistry in the atmospheres of the giant planets. It also provides a sensitive probe of conditions at the 10-microbar level in Jupiter's atmosphere, a region that is strongly influenced by aurora. We performed high-resolution (λ /Δ λ ~ 2,000) spectral observations of C2H4 at 10.53 microns (949.5 cm-1) on Jupiter during June 2000 using Celeste, a Goddard-developed cryogenic echelle spectrometer, in conjunction with the 3.0-m IRTF at Mt. Kea in Hawai'i. Temperature-enhanced ethylene line emission was observed over aurora latitudes, particularly over the northern hemisphere "hot spot" longitude (LIII ~ 180o). We will present preliminary models for these observations using variations in the pressure-temperature profile, altitude-dependent hydrocarbon mixing ratios derived from recent photochemical models, and updated C2H4 line positions and strengths. This work is supported by the NASA Planetary Astronomy Program.