Magnetosphere-ionosphere coupling at Jupiter during Juno’s Prime mission

Abstract

<p>We study magnetosphere-ionosphere coupling at Jupiter during the Juno prime mission, considering magnetic field observations from Juno’s Perijoves 1-32.  We compare the azimuthal magnetic field and the associated determination of Jupiter’s ionospheric meridional Pedersen current, with predictions from a model of magnetosphere-ionosphere coupling developed at the University of Leicester.  We find that the Leicester model closely predicts the magnitude of the residual azimuthal field component of the field across the middle and outer magnetosphere regions, and across the tail.  However, we highlight two areas of discrepancies between the model and the data. On field lines mapping to the outer magnetosphere region, the model predicts an increase in the magnitude of the Bphi component of the magnetic field with ionospheric colatitude, whilst we observe a decrease.  This could suggest that the community needs an updated ionospheric angular velocity flow model for the Juno era. Furthermore, we do not observe the predicted upward-directed current at the boundary between the outer magnetosphere and field lines mapping to the tail.  Currently the model includes a constant ionospheric conductivity.  We suggest that the model might be improved by considering a variable ionospheric conductivity.  Finally, we produce maps of meridional ionospheric currents and discuss the variation of ionospheric currents with local time.</p><p> </p>