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.

The Jovian magnetodisk plays an essential role in the dynamics of the Jupiter system by coupling its various components. Here, we investigate the Juno (JADE, JEDI and MAG) observations of the magnetodisk within 20-80 Jupiter radii (RJ) in the 0-6 hour local time sector. JADE and JEDI data are combined to generate equatorial plane distributions of density, pressure, temperature, and anisotropy of electrons, protons, and heavy ions. Results show: (1) Heavy ions dominate both the number density and pressure. (2) The number density and pressure of all species decrease with radial distance. (3) The temperature increases for electrons and heavy ions and decreases for protons as radial distance increases. (4) On average, the parallel pressure exceeds the perpendicular pressure for all species. Based on these distributions, we explore the equilibrium and dynamics of the magnetodisk and show that: (1) Radial force balance is primarily achieved between the inward magnetic stress and the outward plasma anisotropy force. (2) An examination of the kappa parameters indicates that electrons, protons, and heavy ions primarily undergo adiabatic motion, magnetic moment diffusion, and stochastic motion, respectively. (3) A radial diffusion coefficient is derived from the radial profile of mass, providing an estimate of the timescale for radial transport from 20 to 80 RJ of  7 hours. (4) The total mass (\(5\times10^7\) kg) and thermal energy(\(3.8\times10^{37}\) eV) of the magnetodisk between 20 and 80 RJ are obtained.

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.