Study of Jupiter's auroral regions through the measurements of the JUNO/JIRAM instrument

The Jovian Auroral Infrared Mapper (JIRAM) instrument aboard NASA’s Juno spacecraft was designed to monitor the atmosphere of Jupiter and its aurorae with an unprecedented spatial resolution. In this thesis, JIRAM data measured over the polar regions, have been used to derive quantitative information on the species CH4 and H3+ and on the variability of their spatial distribution. JIRAM spectra have been analysed in the spectral region 3-4 μm, that is particularly favourable for the study of the aurorae. Starting from the data previously analysed for the orbit JM0003, the dataset has been enlarged to include observations outside the auroral ovals with a lower signal and extending the analysis to successive orbits. The first Juno orbits, from JM0003 to JM0091, have been examined to find the most promising for the study of the aurorae. Along with the JM0003, the orbits JM0071 and JM0081 have been analysed for the south aurora. The selected spectra show H3+ and CH4 emissions in the auroral regions and have been analysed using an inversion technique based on a Bayesian approach. Preliminary tests have allowed to optimize for the new dataset the a-priori information vector and the corresponding error and limit the degrees of freedom of the information to just the abundances of the two species and H3+ temperature. The results have confirmed the presence of methane near both poles, within the auroral oval, and comparable abundances of H3+ in the two auroral regions, with values ranging between 2-2.8 10^12 cm^-2 e some peaks larger than 2.8∙10^12 cm^-2. The H3+ temperatures appear lower in the south aurora, where the values do not exceed 825 K, while in the north aurora the temperatures span between 800 K and 950 K. The comparison of these results with the images obtained from the JIRAM’s observations in the L band has also allowed to study the morphology of the Jovian aurorae and to highlight the displacement of a few degrees westward of the south aurora over the time.