Magnetic Silhouettes in Jupiter's Non-Auroral Ionosphere

For decades, the influence of Jupiter's higher order magnetic field on its non-auroral ionosphere has remained enigmatic. NASA's Juno spacecraft has revealed great complexities in the Jovian magnetic field, with significant features in the sub-auroral regions aligning with puzzling structures identified in near-infrared emissions from the ionosphere. Here, we directly compare ground-based measurements of Jupiter's ionosphere with the latest magnetic field models borne in the era of Juno and reveal aspects of global ionosphere-magnetosphere coupling not previously explored. Ionospheric emissions exhibit either enhancements or reductions where the surface field is weakest and are found to correlate with both the strength and geometry of the magnetic field, where the latter is more dominant and with a unique control in each magnetic hemisphere. Therefore, we have illustrated that there may be distinct electrodynamic processes responsible for shaping Jupiter's non-auroral ionosphere in these key regions.