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We present statistical distributions of whistler‐mode chorus and hiss waves at frequencies ranging from the local proton gyrofrequency to the equatorial electron gyrofrequency (fce,eq) in Jupiter's magnetosphere based on Juno measurements. The chorus wave power spectral densities usually follow the fce,eq variation with major wave power concentrated in the 0.05fce,eq–fce,eq frequency range. The hiss wave frequencies are less dependent on fce,eq variation than chorus with major power concentrated below 0.05fce,eq, showing a separation from chorus at M < 10. Our survey indicates that chorus waves are mainly observed at 5.5 < M < 13 from the magnetic equator to 20° latitude, consistent with local wave generation near the equator and damping effects. The hiss wave powers extend to 50° latitude, suggesting longer wave propagation paths without attenuation. Our survey also includes the whistler‐mode waves at high latitudes which may originate from the Io footprint, auroral hiss, or propagating hiss waves reflected to high M shells. Plain Language Summary: Whistler‐mode chorus and hiss waves in Jupiter's magnetosphere are major plasma wave modes, characterized by perturbations in electric and magnetic fields at frequencies from the proton gyrofrequency to the electron gyrofrequency. Chorus waves are typically observed at 0.05fce,eq–fce,eq frequencies (fce,eq is the electron gyrofrequency at the equator) with coherent wave structures. Chorus waves, generated by hot electrons, could cause electron precipitation into the atmosphere and acceleration in the radiation belt. In contrast, hiss waves are usually incoherent with wave frequencies less dependent on fce,eq than chorus. Hiss waves have mixed sources and mainly drive energetic electron loss. Using Juno satellite measurements, we analyze the statistical distribution of chorus and hiss waves in Jupiter's magnetosphere. Our survey reveals different latitudinal coverages and statistical properties of chorus and hiss waves, suggesting their different sources and damping effects. Additionally, our survey includes whistler‐mode waves at high latitudes, potentially originating from various sources such as the Io footprint at the ionosphere, auroral hiss, or reflection of hiss waves at high M shells. The whistler‐mode wave distributions from our study provide valuable insights for future modeling of whistler‐mode wave sources and energetic electron dynamics in Jupiter's magnetosphere. Key Points: Intense chorus waves at 0.05–1 equatorial electron gyrofrequencies (fce,eq) are observed at 5.5 < M < 13 within 20° magnetic latitudesHiss waves from 50 Hz to 0.05 fce,eq have extended latitudinal coverage up to 50° and exhibit propagation effectsHigh latitude (>50°) whistler‐mode waves at 0.05–1 fce,eq are observed in two groups due to different sources [ABSTRACT FROM AUTHOR]

Magnetospheric line radiation (MLR) is a peculiar type of whistler‐mode emissions formed by several similarly spaced spectral lines, whose frequencies may vary with time. These emissions typically occur at frequencies between about 1 and 8 kHz and are observed in both ground‐based and satellite measurements. However, their origin and source locations are not yet understood, as their detection by spacecraft instruments is challenging due to the limited frequency resolution of onboard wave measurements. We use high‐resolution multicomponent wave data obtained by the Van Allen Probes to demonstrate that, in addition to the frequency modulation, MLR events possess a temporal modulation with periods on the order of seconds, which may be related to the wave bouncing between hemispheres. Observed modulation periods are used to estimate a tentative source L‐shell. The modulation periods are shorter for events with larger frequency spacing, and the estimated source L‐shells correlate with model plasmapause locations. Plain Language Summary: Electromagnetic waves with frequencies of a few kHz observed in the near‐Earth space, the magnetosphere, sometimes exhibit distinct frequency modulation. When represented in traditional frequency‐time spectrograms, with wave intensity color‐coded as a function of frequency and time, these waves appear as several nearly equidistant spectral lines. They are called magnetospheric line radiation (MLR). Although they have been observed by both ground‐based and spacecraft instruments, their origin is still not understood. We use high‐resolution data obtained by the Van Allen Probes spacecraft to show that MLR intensity is modulated not only in frequency but also in time, with modulation periods on the order of seconds. The available wave measurements allow us to determine not only wave intensity but also propagation directions. This is used to demonstrate that the observed temporal modulation corresponds, with some uncertainties, to a wave element bouncing back and forth between hemispheres. Using the theory of wave propagation in plasma, the bouncing periods can be used to calculate the distance of the magnetic field line where the wave bounces, that is, the distance of a tentative wave source. Our results help to understand possible generation mechanisms and source locations of these peculiar emissions. Key Points: Magnetospheric line radiation may have a fine temporal structure related to the wave bouncing between hemispheresAnalysis of the corresponding modulation periods allows estimation of the L‐shell of a tentative sourceTentative source locations of analyzed events with the fine temporal structure correlate with the model plasmapause locations [ABSTRACT FROM AUTHOR]

Interchange instability is known to drive fast radial transport of electrons and ions in Jupiter's inner and middle magnetosphere. In this study, we conduct a statistical survey to evaluate the properties of energetic particles and plasma waves during interchange events using Juno data from 2016 to 2023. We present representative examples of interchange events followed by a statistical analysis of the spatial distribution, duration and spatial extent. Our survey indicates that interchange instability is predominant at M‐shells from 6 to 26, peaking near 17 with an average duration of minutes and a corresponding M‐shell width of <∼0.05. During interchange events, the associated plasma waves, such as whistler‐mode, Z‐mode, and electron cyclotron harmonic waves exhibit a distinct preferential location. These findings provide valuable insights into particle transport and the source region of plasma waves in the Jovian magnetosphere, as well as in other magnetized planets within and beyond our solar system. Plain Language Summary: The radial transport of plasma around a magnetized planet is crucial for understanding the underlying magnetospheric dynamics. Jupiter's magnetospheric dynamics are primarily dominated by the rapid rotation and plasma source from Io. This rapid rotation drives the interchange instability, where hot, low‐density plasma is moved toward the inner magnetosphere. During this process, the inward moving flux tube builds up magnetic pressure, potentially leading to the trapping of particles alongside plasma waves. In this study, we present several typical examples of interchange events, and conduct a statistical analysis to explore their spatial distribution, duration and spatial extent, as well as the typical features of the associated plasma waves. This survey provides insights into mass transport, the source of these plasma waves in Jupiter's magnetosphere, with potential implications for other magnetized planets within and beyond our solar system. Key Points: Our statistical survey indicates that interchange events occur over L (or M)‐shells ∼6–26 at Jupiter with a peak occurrence rate at M ∼ 17During interchange events, various types of plasma waves are intensified, each exhibiting a distinct preferential locationThe duration and the corresponding spatial extent of interchange events are analyzed for multiple events [ABSTRACT FROM AUTHOR]

Juno conducted two close Io flybys on 30 December 2023 and 03 February 2024, both at a minimum altitude of 1,500 km. Filamentary structures in the electric and magnetic field spectra indicate Juno crossed the Alfvén wing, the magnetic structure connecting Io to Jupiter's polar ionosphere. We show that the first pass took Juno diametrically through the northern Alfvén wing, while the second pass had Juno graze the southern Alfvén wing boundary, enabling extended measurements of the transition region between Io's vicinity and the Jovian magnetosphere. Of note, evidence of local electron beams is inferred from whistler‐mode emissions. We demonstrate that their energies are sub‐keV, are sourced from Io's ionosphere or local torus, and are part of a distributed current system connecting Io to Jupiter. Finally, upper hybrid resonances indicate electron densities are significantly elevated in Io's polar region (∼28,000 cm−3) compared to the local Io torus (∼2,000 cm−3). Plain Language Summary: Juno conducted two close Io flybys. Signatures in the electromagnetic field indicate that Juno sampled the region dominated by the electrodynamic interaction between Io and Jupiter. Powerful electric currents flow within this region that deliver energetic electrons into Jupiter's polar atmosphere, resulting in the Io auroral footprint. Juno also spent an extended period along the boundary of this region, providing an in situ view of the complexity of this region's structure. Local density measurements indicate significantly elevated densities in Io's poles. Key Points: Juno plasma wave observations are consistent with Alfvén wing crossings during close Io flybysWhistler‐mode radiation indicate the presence of sub‐keV electron beams operating just outside the Alfvén wingElectron densities are significantly elevated in Io's polar region [ABSTRACT FROM AUTHOR]

Over 40 years ago it was suggested that electron loss in the region of the radiation belts that overlaps with the region of high plasma density called the plasmasphere, within four to five Earth radii (1, 2), arises largely from interaction with an electromagnetic plasma wave called plasmaspheric hiss (3-5). This interaction strongly influences the evolution of the radiation belts during a geomagnetic storm, and over the course of many hours to days helps to return the radiation-belt structure to its 'quiet' pre-storm configuration. Observations have shown that the long-term electron-loss rate is consistent with this theory but the temporal and spatial dynamics of the loss process remain to be directly verified. Here we report simultaneous measurements of structured radiation-belt electron losses and the hiss phenomenon that causes the losses. Losses were observed in the form of bremsstrahlung X-rays generated by hiss-scattered electrons colliding with the Earth's atmosphere after removal from the radiation belts. Our results show that changes of up to an order of magnitude in the dynamics of electron loss arising from hiss occur on timescales as short as one to twenty minutes, in association with modulations in plasma density and magnetic field. Furthermore, these loss dynamics are coherent with hiss dynamics on spatial scales comparable to the size of the plasmasphere. This nearly global-scale coherence was not predicted and may affect the short-term evolution of the radiation belts during active times., We analyse in detail the magnetic conjunctions between the Van Allen probes (a NASA Earth-orbiting satellite mission) (6) and the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) balloons [...]