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Inter‐Orbit Variability of Jupiter's Current Sheet Morphology.

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Title: Inter‐Orbit Variability of Jupiter's Current Sheet Morphology.
Authors: Santos, A.1 (AUTHOR) alexandre.santos.21@ucl.ac.uk, Achilleos, N.1 (AUTHOR), Millas, D.1,2 (AUTHOR), Guio, P.1,3 (AUTHOR), Dunn, W.1 (AUTHOR), Provan, G.4 (AUTHOR), Nichols, J. D.4 (AUTHOR), Arridge, C. S.5 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Jun2026, Vol. 131 Issue 6, p1-24. 24p.
Subject Terms: Current sheets, Magnetosphere, Plasma flow, Solar wind, Magnetospheric physics, Magnetopause, Juno (Space probe), Plasma currents
Abstract: The structure of Jupiter's magnetosphere reflects the combined effects of a strong intrinsic field and an extended hinged current sheet whose morphology varies with solar wind forcing. We present a study of Jupiter's magnetodisc that combines the UCL‐AGA magnetodisc code with Khurana's generalized, hinged current sheet models (1992/2022) to fit Juno MAG data from orbits PJ6–PJ12 and PJ34 using a "rolling‐window" approach. Periods of relative stability ("quiescent" magnetosphere) are identified during each pass, reducing the impact of transient solar‐wind and reconfiguration events. The underlying magnetospheric parameters are then determined and current sheet morphology constrained. Estimated magnetopause distances are also obtained and compared to the results obtained by Joy et al. (2002, https://doi.org/10.1029/2001ja009146), showing most probable subsolar standoff distances between 46 and 64 RJ ${R}_{J}$ and results consistent with dawn‐dusk asymmetry and/or a cushion region along the dusk flank. This approach reveals substantial per‐perijove magnetospheric and current sheet geometry variability, as well as capturing changes in hot‐plasma content Kh $\left({K}_{h}\right)$ and effective magnetodisc radius rmax $\left({r}_{\text{max}}\right)$ within a single pass. Correlations between model parameters link extended magnetospheres to larger magnetic field sweepback onset distances, with weaker negative trends linking magnetospheric compression with the Alfvén wave propagation speed and hot plasma content with the distance at which hinging becomes significant. Finally, both MDISC + Khurana model variants are shown to match, and often outperform, the optimized Connerney (2020) baseline current disc model across most perijoves analyzed. Plain Language Summary: Jupiter's magnetosphere is powered by the planet's strong magnetic field, fast rotation, and the field of an extended plasma current sheet, which can dominate at large distances from the planet. The pressure exerted by the solar wind and flow direction impart additional hinging effects to this structure and further shape the global configuration, which is expected to vary substantially between Juno orbits. By coupling the latest UCL‐AGA model with current sheet geometry models, we analyze those variations and devise a framework that identifies periods of relative magnetospheric stability. The performance of the combined models are compared to Connerney2020, a widely used model of current sheet field, and correlations are determined between the current sheet and the structure of Jupiter's magnetosphere. Key Points: "Rolling‐window" approach used to identify periods of quiescent magnetosphere during Juno's PJ6‐PJ12 and PJ34 orbitsMagnetodisc conditions and current sheet morphology determined for each perijove, revealing a dynamic and interconnected relationExtended magnetospheric configurations show correlation with larger magnetic field sweepback onset distances [ABSTRACT FROM AUTHOR]
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Abstract:The structure of Jupiter's magnetosphere reflects the combined effects of a strong intrinsic field and an extended hinged current sheet whose morphology varies with solar wind forcing. We present a study of Jupiter's magnetodisc that combines the UCL‐AGA magnetodisc code with Khurana's generalized, hinged current sheet models (1992/2022) to fit Juno MAG data from orbits PJ6–PJ12 and PJ34 using a "rolling‐window" approach. Periods of relative stability ("quiescent" magnetosphere) are identified during each pass, reducing the impact of transient solar‐wind and reconfiguration events. The underlying magnetospheric parameters are then determined and current sheet morphology constrained. Estimated magnetopause distances are also obtained and compared to the results obtained by Joy et al. (2002, https://doi.org/10.1029/2001ja009146), showing most probable subsolar standoff distances between 46 and 64 RJ ${R}_{J}$ and results consistent with dawn‐dusk asymmetry and/or a cushion region along the dusk flank. This approach reveals substantial per‐perijove magnetospheric and current sheet geometry variability, as well as capturing changes in hot‐plasma content Kh $\left({K}_{h}\right)$ and effective magnetodisc radius rmax $\left({r}_{\text{max}}\right)$ within a single pass. Correlations between model parameters link extended magnetospheres to larger magnetic field sweepback onset distances, with weaker negative trends linking magnetospheric compression with the Alfvén wave propagation speed and hot plasma content with the distance at which hinging becomes significant. Finally, both MDISC + Khurana model variants are shown to match, and often outperform, the optimized Connerney (2020) baseline current disc model across most perijoves analyzed. Plain Language Summary: Jupiter's magnetosphere is powered by the planet's strong magnetic field, fast rotation, and the field of an extended plasma current sheet, which can dominate at large distances from the planet. The pressure exerted by the solar wind and flow direction impart additional hinging effects to this structure and further shape the global configuration, which is expected to vary substantially between Juno orbits. By coupling the latest UCL‐AGA model with current sheet geometry models, we analyze those variations and devise a framework that identifies periods of relative magnetospheric stability. The performance of the combined models are compared to Connerney2020, a widely used model of current sheet field, and correlations are determined between the current sheet and the structure of Jupiter's magnetosphere. Key Points: "Rolling‐window" approach used to identify periods of quiescent magnetosphere during Juno's PJ6‐PJ12 and PJ34 orbitsMagnetodisc conditions and current sheet morphology determined for each perijove, revealing a dynamic and interconnected relationExtended magnetospheric configurations show correlation with larger magnetic field sweepback onset distances [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2025JA034864