Temperature and Composition Disturbances in the Southern Auroral Region of Jupiter Revealed by JWST/MIRI

Jupiter's South Polar Region (SPR) was observed by James Webb Space Telescope/Mid-Infrared Instrument in December 2022. We used the Medium Resolution Spectrometer mode to provide new information about Jupiter's South Polar stratosphere. The southern auroral region was visible and influenced the atmosphere in several ways: (a) In the interior of the southern auroral oval, we retrieved peak temperatures at two distinct pressure levels near 0.01 and 1 mbar, with warmer temperatures with respect to non-auroral regions of 12 ± 2 K and 37 ± 4 K respectively. A cold polar vortex is centered at 65°S at 10 mbar. (b) We found that the homopause is elevated to (Formula presented.) km above the 1-bar pressure level inside the auroral oval compared to (Formula presented.) km at neighboring latitudes and with an upper altitude of 350 km in regions not affected by auroral precipitation. (c) The retrieved abundance of C₂H₂ shows an increase within the auroral oval, and it exhibits high abundances throughout the polar region. The retrieved abundance of C₂H₆ increases toward the pole, without being localized in the auroral oval, in contrast with previous analysis (Sinclair et al., 2018, https://doi.org/10.1016/j.icarus.2017.09.016). We determined that the warming at 0.01 mbar and the elevated homopause might be caused by the flux of charged particles depositing their energy in the SPR. The 1-mbar hotspot may arise from adiabatic heating resulting from auroral-driven downwelling. The cold region at 10 mbar may be caused by radiative cooling by stratospheric aerosols. The differences in spatial distribution seem to indicate that the hydrocarbons analyzed are affected differently by auroral precipitation.