The vertical structure of the Jovian atmosphere

An inhomogeneous atmospheric model, which includes both polarizing aerosols and methane gas, has been developed for the equatorial and tropical regions of Jupiter consistent with the Pioneer polarimetry and photometry data as well as the methane-band data of West (1979a, Icarus 38, 12-33). A two-cloud model with an overlying stratospheric haze has been used to explain the relative strengths of weak and strong methane bands. The upper cloud, assumed to be composed primarily of ammonia crystals, is denser in the zones (5-8 optical depths) than the belts (3-4 optical depths) when viewed in red light. There is also a compositional difference; an increase in the concentration of the unknown chromophore lowers the blue albedo in the belts. Otherwise, belts and zones are remarkably similar. The cloudtops are found between 200 and 230 mbar and the cloud extends down to the saturated vapor pressure of ammonia at 700 mbar; a haze of 0.3 ± 0.1 optical depths overlies all regions. For all the regions studied, the polarization measurements are best fit with a negatively polarizing ammonia cloud (-20%) beneath a positively polarizing haze (40-50%). Unlike the nearby features, the Equatorial Region and the Great Red Spot have a negative polarization at 80° phase angle implying less gas above the clouds in these regions, a conclusion supported by the increased brightness at 8900 Å. Tables are presented giving the preferred model parameters for each region studied.