[P-PS01] Outer Solar System Exploration Today, and Tomorrow

[PPS01-11] Jupiter’s First Pole-To-Pole Vertical Ionospheric Profiles From JWST

★Invited Papers

*Paola Tiranti¹、Henrik Melin¹、Luke Moore²、Tom S Stallard¹、James O'Donoghue³、Katie L Knowles¹、Khalid Mohamed²、Kate Roberts²、Emma M Thomas¹ (1.Northumbria Univ.、2.Boston Univ.、3.Univ. of Reading)

キーワード：Jupiter, Upper Atmosphere, JWST

JWST programme #3665 successfully observed ionospheric emissions above Jupiter’s limb in September 2023, December 2023 and January 2024, exploring the tenuous upper atmosphere of Jupiter. Using NIRSpec’s IFU at ~319 km/spaxel resolution, we retrieve the first-ever pole-to-pole vertical profiles of Jupiter’s ionosphere at both dawn and dusk, detecting structures up to 5000 km in altitude. We analyse vertical H₃⁺ temperature and ion density variations to probe the ionosphere as a function of latitude and local-time. We find a dawn-dusk asymmetry at sub-auroral and equatorial latitudes, with surprising higher densities at dawn compared to dusk, particularly in the region between 1500-1700 km. Further, results indicate strong temperature gradients away from the poles, especially at dusk. These results provide crucial observational constraints on ionospheric dynamics, shedding light on where H₃⁺ is produced at dawn and how its morphology evolves planet-wide at dusk and beyond. This work has the potential to impact current 1D and 3D magnetosphere-ionosphere-thermosphere models and provide critical context for the first Juno radio occultation (ROX) occurred on the same date in September 2023, with the additional goal of setting the scene for subsequent ROXs.