Zonal Features in the Behavior of Weak Molecular Absorption Bands on Jupiter

Abstract

Based on the spectral observations of Jupiter carried out over recent years, we consider the behavior of weak molecular absorption bands of methane and ammonia in a wavelength range of 600−800 nm. In the latitudinal behavior of the intensity of these bands, rather clearly expressed features, demonstrating a connection with the zonal structure of cloud belts of the planet, are traced. However, for different bands, the positions of the absorption extrema in latitude somewhat differ. The changes in the zonal spectra show the weakening in absorption observed toward the disk edge, which is most probably connected with the radiative transfer geometry in an optically active layer of the atmosphere. The importance of studying the weak absorption bands is stressed, since precisely these bands make it possible to analyze the structural features and their variations in the troposphere of Jupiter. When interpreting the observational data, it is necessary to consider at least two alternative models for forming the absorption bands. One of them should deal with an optically thick layer of ammonia clouds, where the multiple scattering on particles in this layer plays the main part in producing the molecular absorption bands. The second model should be based on the assumption of a small optical thickness of the ammonia cloud layer, according to which the absorption is mainly formed under clouds, where the scattering on a pure gaseous component is weak.