Spatial variations of methane absorption on Jupiter according to the results of quasicontinuous CCD spectrophotometry

Spectrophotometry observations of Jupiter were carried out during four nights in November–December 1999. Three hundred and eighty eight CCD-spectrograms of the central meridian of the planet were obtained and processed with doubly overlapped longitudes with a step of 1.8°. Latitudinal variations in central depths of methane absorption bands were studied corresponding to the wavelengths of 619, 725, 798, and 887 nm. It has been shown that these variations are mainly present at all longitudes, but for different absorption bands the positions of maxima and minima do not coincide. Zonal differences do not correlate with positions of dark and bright cloud belts in absorption, with one exception for the band 887 nm, which for a long time shows a well-expressed minimum in the equatorial zone of Jupiter. The 798 nm band reveals great dispersion of the depths at low latitudes as compared to other bands, which can be related with the presence of the ammonium absorption band. Comparison of the latitudinal absorption band variability at wave-lengths 619 and 725 nm shows a “loop-like” form of the relation between the depths of these bands in the low-latitude zone of Jupiter. Indicative estimates of the effective optical depth formation and absorption and their difference in the framework of simple two-layer model indicate the existence of vertical heterogeneity of the cloud cover varying with latitude.