H3+ auroral densities, cooling rate and conductance from Juno FUV and infrared observations

Auroral precipitation significantly enhances the H3+ ion density in the Jovian ionosphere as a result of the creation of H2+ ions followed by charge transfer on ambient H2 molecules. This density enhancement has several important consequences:
- it generates additional cooling through infrared radiation to space (the H3+ thermostat effect) -it increases the ionospheric conductance which is an important component of the current loops connecting the Jovian magnetosphere and ionosphere - it makes it possible to image the auroral structures at high latitude - it provides an excellent remote sensing tool to probe the thermospheric temperature.
During a few perijove passes, simultaneous infrared (JIRAM) and ultraviolet (UVS) quasi-global maps of the Jovian aurora are available. The globally integrated H3+ cooling power is in the range 2-4 terawatts in both hemispheres, close to the particle heating power. We use the FUV H2 brightness and color ratio to derive the characteristics of the electron precipitation and model the H+3 radiance for each UVS map pixel. Comparison of H3+ modeled radiance maps with the JIRAM observations generally shows good agreement, with some localized differences. The spatially integrated H3+ cooling powers from the model are in close agreement with the global JIRAM values. In this presentation, we compare the H+3 column density derived from the UVS images and model with values in the literature based on H+3 ground based spectral measurements. We also illustrate the H+3 density altitude distribution at different locations and investigate its dependence on the methane profile we use. These results will be useful for validation of 3-D models of the global Jovian energy balance in the upper atmosphere.