ACETYLENE FORMATION ON JUPITER - PHOTOLYSIS OR THUNDERSTORMS

The far-uv photolysis of methane, diluted 1000 times with hydrogen, was studied experimentally at 300 and 200°K. Acetylene was found to be formed along with other hydrocarbons. Two models are discussed in view of the experimental results. (a) Orton and Aumann's [(1977) Icarus 32] model, in which the Acetylene extends down only to the ∼15 mbar level. In this case the agreement between the rates of acetylene production and destruction by photolysis is quite good. (b) If Orton and Aumann's model is incorrect, [their observations being inconsistent with the observations of Tokunaga, Knacke, and Owen (1976) Astrophys. J. 209] and the acetylene extends down all the way to the ammonia clouds, an additional source of acetylene is required. Such a source might well be thunderstorms in the Jovian clouds. If thunderstorms do operate in the Jovian atmosphere, the conversion efficiency of thermal energy into lightning energy on Jupiter should be only 24 times larger than in the Earth's tropics. This difference is similar to the difference by a factor of 20 between the Earth's tropics and midlatitude regions. © 1979.