Recent observations from Juno provided a detailed view of Jupiter’s magnetodisk, including its magnetic fields, waves, plasmas and energetic particles. Here, we contribute to Juno results by determining the electric currents threading the magnetodisk and their coupling to field-aligned currents (FAC) in the midnight-to-dawn local time sector. We first derive from Juno magnetic field data the spatial distributions of the height-integrated radial (Ir) and azimuthal (Ia) currents in the magnetodisk, and then calculate the FACs from the divergence of the two current components. The Ir-associated FAC, Jr, flows into and out of the magnetodisk at small and large radial distances, respectively, approximately consistent with the axisymmetric corotation enforcement model. On the other hand, Ia decreases with increasing local time everywhere in the local time sector covered, indicating an additional FAC (Ja) flowing out of the magnetodisk. From Ia and Ja, we conclude that the influence of the solar wind, which compresses the dayside magnetosphere and thus breaks the axisymmetry of currents and fields, reaches deep to a radial distance of at least 20 Jupiter radii. Our results provide observational constraints on Jupiter’s magnetosphere-ionosphere-thermosphere coupling current systems, on their relation to the main auroral emission and on the radial mass transport rate in the magnetodisk, which we estimate to be close to ~1500 kg/s.

We investigate electrostatic waves in a magnetopause reconnection diffusion region event. In the electron diffusion region on the magnetospheric side, an oblique electrostatic wave is observed. The local distribution exhibits fast non-gyrotropic electron beams with drifts comparable to the electron thermal speed, but the wave has a much lower phase speed. Response of ions and possible cold electrons may contribute to wave excitation. Near the current sheet mid-plane, parallel electron beam-mode waves are modulated by whistler waves. In the separatrix region, parallel waves associated with field-aligned electron beams and perpendicular electron cyclotron waves with loss cone distributions exhibit modulation frequencies in the lower-hybrid wave frequency range. We infer that lower-hybrid waves scatter electrons to produce beams and alter loss cones to modulate electrostatic waves. The results advance our understanding about the regimes and mechanisms of electrostatic waves in reconnection and their coupling with lower-frequency waves.