JIRAM/Juno limb observations of H3+ in the mid- and low latitude Jovian atmosphere

Abstract

NASA's Juno mission has been investigating Jupiter since August 2016, providing unprecedented insights into the giant planet's atmosphere. The Jupiter Infrared Auroral Mapper (JIRAM) experiment, on board Juno, performed spectroscopic observations of the H3+ emissions in both auroral regions (Dinelli et al., 2017; Adriani et al., 2017; Mura et al., 2017) and at mid-latitudes. In this work we analyse observations acquired over five orbits by the JIRAM spectrometer during the period from August 2016 to March 2017. In particular, during these observations, the spectrometer slit sampled Jupiter's limb over latitudes ranging from 60∘ equatorward, in both hemispheres. Limb spectra show typical H3+ emission features in the 3-4 μm spectral band, used to retrieve the H3+ densities and temperatures. Spatial resolution of the limb observations ranges between 50 and 130 km and is favourable for investigating the vertical distribution of H3+. Vertical profiles of H3+ limb intensities, in the 3-4 μm spectral band, are presented along with preliminary retrievals of the vertical profiles of H3+ volume mixing ratio (VMR). We compare our results with predictions from various atmospheric models. Acknowledgments The project JIRAM is funded by the Italian Space Agency.