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Short large-amplitude magnetic field structures (SLAMSs) are often seen upstream of quasi-parallel shocks. They play vital roles near the quasi-parallel shock, such as decelerating solar wind ions and contributing to the dissipation and reformation of the shock. The formation process of these structures has attracted great attention and has long been realized in simulation. However, their formation mechanism is still full of mysteries. Here, using magnetospheric multiscale mission (MMS) observation, we provide direct observations of the SLAMS formation and destruction processes. SLAMS growth is powered by solar wind ions and shock-reflected ions through the ion-ion non-resonant mode. Reconnection occurs between and inside SLAMSs during their growth; however, these cumulative changes in magnetic field topology and the dissipation of the magnetic field energy contribute to the destruction of the SLAMS. These observations shed new light on the dissipation and reformation of the shock both in space physics and astrophysics. [ABSTRACT FROM AUTHOR]

Magnetic reconnection, an essential mechanism in plasma physics that changes magnetic topology and energizes charged particles, plays a vital role in the dynamic processes of the Jovian magnetosphere. The traditional Vasyliūnas cycle only considers the effect of magnetic reconnection at the nightside magnetodisk. Recently, magnetic reconnection has been identified at the dayside magnetodisk in Saturn's magnetosphere and can impact dayside auroral processes. In this study, we provide the first evidence that the dayside magnetodisk reconnection can also occur at Jupiter. Using data from the Galileo and Voyager 2 spacecraft, we have identified 18 dayside reconnection events with radial distances in the range of 30–60 Jupiter radii (RJ). We analyzed the particle (electron and ion) flux, energy spectra, and characteristic energy of these dayside events and compared them to the nightside events. The statistical results show that the energy spectra and characteristic energy of electrons/ions in dayside and nightside magnetic reconnection events are comparable. On average, the characteristic energy of ions on the dayside is higher than that on the nightside. Based on the limited data set, we speculate that the occurrence rate of dayside magnetodisk reconnection should be significant. The dayside Jovian magnetodisk reconnection seems to have a comparable effect on providing energetic particles as that at nightside and to be one of the key processes driving dynamics within the Jovian magnetosphere. Plain Language Summary: Jupiter has the strongest magnetic field among the planets in our solar system. Particles in the space around Jupiter are affected by its magnetic field. Changes in the strength and structure of the local magnetic field, known as magnetic reconnection, cause those particles to undergo rapid acceleration leading to their energization. In the past, magnetic reconnection was thought to be difficult to occur on Jupiter's dayside magnetodisk. In contrast, the recent observation of reconnection at Saturn's dayside magnetodisk strongly implied the possibility of a similar process at Jupiter. In this paper, taking advantage of the archived data from the Galileo and Voyager 2 spacecraft, we provide the first evidence that the dayside magnetodisk reconnection can occur at Jupiter and have an important effect on the energization of particles. Key Points: Dayside magnetodisk reconnection events at 30–60 RJ are identified in the Jovian magnetosphere for the first time18 dayside events are analyzed to compare with nightside events regarding particle flux, energy spectra, and characteristic energyMagnetodisk reconnection at the dayside is as effective as that at the nightside in providing energetic particles to the magnetosphere [ABSTRACT FROM AUTHOR]

Ultra‐low‐frequency (ULF) waves emerge as pivotal factors in elucidating the mechanisms that drive the intricate dynamics of radiation belt electrons within the plasmasphere and plasmaspheric plumes. Utilizing THEMIS data from September 2012 to September 2017, we conducted a comprehensive statistical analysis of Pc4‐5 ULF waves within and outside the plasmaspheric plume. Our findings reveal a distinctive dawn‐dusk asymmetry in occurrence rate and wave power of poloidal mode waves in the absence of the plume, resembling the toroidal mode asymmetry observed. Poloidal mode waves exhibit a higher likelihood of formation within the plume, while the toroidal mode waves show the opposite trend, contributing to the elevated dusk‐side occurrence rate of poloidal mode waves. Moreover, both wave modes within the plume demonstrate lower peak frequencies compared to waves outside the plume. The global distribution of wave power within the plume suggests higher power at noon than on the dusk side. Plain Language Summary: In this work, we report the statistical analysis of Pc4‐5 ULF waves both within and outside the plasmaspheric plume. We discovered a noticeable difference between the dawn and dusk sides in how often and how strongly poloidal and toroidal mode waves occur when the plasmaspheric plume is absent. Intriguingly, poloidal mode waves are more likely to form within the plume, while toroidal mode waves tend to do the opposite. This leads to a higher occurrence of poloidal mode waves on the dusk side. Additionally, both wave types within the plume have lower peak frequencies than those outside the plume. The power of both types of waves within the plasmaspheric plume, the toroidal and poloidal modes, is higher around noon compared to the dusk side. This indicates that the solar wind dynamic pressure and the plasmaspheric plume's connection with the flanks play a crucial role in creating and spreading ULF waves. Key Points: The Pc4‐5 ULF waves in the presence and absence of plasmaspheric plume at L ∼ 6–12 are statistically studied by THEMIS satellitesThe majority of waves within the plasmaspheric plume are poloidal waves, and the majority of waves outside the plasmaspheric plume are toroidal wavesThe plasmaspheric plume has a significant effect on the wave properties of poloidal mode waves and toroidal mode waves [ABSTRACT FROM AUTHOR]

The effects of plasma density on the plasmaspheric hiss amplitude and its spatial and temporal scale sizes are investigated using data from Van Allen Probes A and B. The plasmaspheric hiss amplitude and scale sizes are found to be more affected by the small‐scale density variations than the overall density profile of the plasmasphere. In detail, our results suggest that both the hiss wave amplitude and its scale sizes are (a) related to the total electron density when the density is less than ∼1,000 cm−3; (b) independent of the total electron density when the density is greater than ∼1,000 cm−3; and (c) better correlated with the detrended density (removing the background plasmasphere density profile from the total electron density) regardless of the density value. Key Points: Effects of plasma density on the spatial and temporal scale sizes of plasmaspheric hiss amplitude is statistically investigatedThe plasmaspheric hiss amplitude is better correlated with the detrended electron density than the total electron densityThe spatial and temporal scale sizes of plasmaspheric hiss are mainly related to that of the relatively small‐scale density variations [ABSTRACT FROM AUTHOR]