Latitudinal Temperature Variations of Jovian H⁺₃

A spectral image of Jupiter centred on 3.45 μm, taken on the night of April 2, 1992, using cooled grating spectrometer CGS4 on the United Kingdom Infrared Telescope, shows that features due to the v₂ ro-vibrational band of H⁺₃ extend right across the planet. Analysis of these features indicates that the jovian disk may be divided into three regions-two mid-high latitude regions with temperatures around 800 K and a hotter, central region with a temperature around 1200 K. The central meridian longitude of the image in the jovian System III is 102°, coinciding with the region of the Lyman-α Bulge. The significance of new work on the bulge for understanding this image is discussed. The image also shows an interesting doublet centred on 3.52 μm. Candidates for this feature are discussed; none is found to be satisfactory.