Abstract/Summary

We present the first pole-to-pole observations of Jupiter's ionosphere, capturing dawn and dusk vertical structure up to 5,000 km altitude using the James Webb Space Telescope (JWST), simultaneous to Juno's radio occultation experiments (ROX) in September 2023. We produce vertical temperature global maps showing largely constant temperatures with altitude. Mean temperatures range from 650 K at low latitudes to 800 K at high latitudes. Auroral emissions were observed at the north and south pole, with northern temperature profiles showing signatures of localized heating (up to 1900 K) at low altitudes. Temperature-latitude gradients exhibit steeper slopes at dusk compared to dawn at all altitudes, particularly between 1,500 and 1,700 km. We also produce the first pole-to-pole vertical volumetric number density map, with auroral densities of up to peaking near 1,500 km altitude. We find a dawn-dusk asymmetry at sub-auroral and equatorial latitudes, with higher densities at dawn ( ) compared to dusk ( ) between 1,500 and 1,700 km. While photochemical equilibrium (PCE) theory predicts higher densities at dusk, the presence of enhanced dawn densities implies that additional processes—such as particle precipitation and plasma transport, particularly at high and mid latitudes—play a significant role in shaping the ionospheric structure.