Magnetosphere-ionosphere coupling at Jupiter: Expectations for Juno Perijove 1 from a steady state axisymmetric physical model

We evaluate the expected effects of magnetosphere-ionosphere coupling at Jupiter along the Juno Perijove 1 (PJ1) trajectory using an axisymmetric physical model. As found at Saturn, the model predicts distributed downward field-aligned currents over polar regions mapping to the tail and outer magnetosphere, closed principally through a ring of upward current mapping to the middle magnetosphere, which requires downward acceleration of magnetospheric electrons generating Jupiter's main auroral emission. Auroral location, width, intensity, electron energy, and current density are in accord with values derived from previous ultraviolet imaging, such that the model forms an appropriate baseline for comparison with Juno data. We evaluate the azimuthal field perturbations during six anticipated near-planet encounters with middle magnetosphere field lines at radial distances between ~1.6 and ~16 Jovian radii, discuss the expected form of the accelerated electron distributions, and comment briefly on model expectations in relation to first results derived from Juno PJ1 data.

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CC BY 4.0