A New Semi-Empirical Model of Ganymede’s Magnetosphere

To prepare for the arrival of the JUICE (JUpiter ICy moons Explorer) mission, developing a comprehensive and physically grounded magnetic field model is essential to understand the interactions with charged particles and the complicated plasma dynamics. Existing models range from simplified representations, such as the model only include dipole field and induced ocean, to computationally intensive magnetohydrodynamic (MHD) or hybrid simulation codes, yet a critical gap remains for a model balancing physical fidelity with computational efficiency. We aim to present the development of a semi-empirical magnetic field model of Ganymede, based on the frameworks used for Mercury and Earth. Our superposition model integrates observational constraints with theoretical insights to accurately represent the Jovian background field and Alfvén wing, Ganymede’s internal field, the ocean-induced field, and the field generated from different currents in Ganymede’s magnetosphere. The model enables rapid, scalable simulations of particle access across the magnetosphere. It will support mission planning, enhance the interpretation of JUICE data, and provide key predictions for particle-driven surface processes on magnetized icy moons. Ultimately, this work enhances our understanding of moon-magnetosphere interactions and the dynamic interplay between internal fields, induced currents, and external plasma environments.