The influence of ethane and acetylene upon the thermal structure of the Jovian atmosphere

Ethane and acetylene, both of which possess more efficient emission bands than methane, have been incorporated into a thermal structure model for the atmosphere of Jupiter. Choosing for illustrative purposes the mixing ratios $\text{[}\text{C}{}_2\text{H}{}_6\text{]}\text{[}\text{H}{}_2\text{]}\text{= 10}{}^{\mathrm{?5}}$ and $\text{[}\text{C}{}_2\text{H}{}_2\text{]}\text{[}\text{H}{}_2\text{]}\text{= 5 × 10}{}^{\mathrm{?7}}$, it is found that these hydrocarbon gases lower the atmospheric temperature within the thermal inversion region by as much as 20 K, subsequently reducing the emission intensity of the 7.7 μm CH₄ band below the observed result. It is qualitatively shown, however, that this cooling by C₂H₆ and C₂H₂ could be compensated by aerosol heating resulting from a uniformily mixed aerosol which absorbs 15% of the incident solar radiation. Such aerosol heating has been suggested by uv albedo observations.