Abstract/Summary

Global temperatures in Jupiter's upper atmosphere are poorly constrained. Other than an in situ measurement by the Galileo Probe, all temperature data come from remote-sensing methods that primarily rely on emissions from H3+, the dominant molecular ion in giant planet ionospheres. While H3+ temperature serves as a proxy for thermospheric temperature under specific conditions, the available H3+ observations at Jupiter have limited spatial coverage and a wide range of reported temperatures that complicate analysis of atmospheric temperatures. We present high-resolution H3+ temperature maps near local solar noon collected over 3 half-nights in 2022 and 2023. Pole-to-pole temperature structure is consistent across time spans of 1 month to 1 yr. Median equatorial (±25° latitude) temperature across all three nights is 762 ± 43 K, with night-to-night differences of <75 K. Temperatures within the statistical locations of the northern and southern auroral ovals are 1200 ± 96 K and 1143 ± 120 K, respectively. A region ∼30 K cooler than its surroundings is found near 20° N, 90° W System III longitude, roughly coincident with a magnetic field anomaly, providing additional evidence for magnetic influence on Jupiter's upper atmosphere. Temperatures generally decrease smoothly from auroral to equatorial latitudes, consistent with the expected gradient if Jupiter's nonauroral latitudes are heated primarily by dynamical redistribution of auroral energy.