[1] A three-dimensional global-scale hybrid simulation is carried out, for the first time, for dynamics of the dayside bow shock-magnetosphere system associated with the quasi-parallel bow shock. A case with IMF along the Sun-Earth line is examined in detail. First, the foreshock waves and the associated shock reformation process are investigated. In particular, the generation and structure of diamagnetic cavities, with a decrease in the magnetic field and density, in the foreshock of the quasi-parallel shock are discussed. Second, the interaction of the foreshock-originated pressure pulses with the dayside magnetosphere is simulated. The diamagnetic cavities that are generated in the turbulent foreshock due to the ion beam plasma interaction are found to lead to strong surface perturbations at the magnetopause. Third, the coupling between the pressure pulses and the magnetosphere is studied. The compressional waves are found to mode convert to shear Alfvén waves and kinetic Alfvén waves through the Alfvén resonance process in nonuniform plasmas. The shear Alfvén waves lead to field line resonance, which corresponds to the fundamental odd resonance wave number, and produce field-aligned currents in the dipole magnetospheric field.Citation: Lin, Y., and X. Wang (2005), Three-dimensional global hybrid simulation of dayside dynamics associated with the quasiparallel bow shock,

2014), Investigation of storm time magnetotail and ion injection using three-dimensional global hybrid simulation, Abstract Dynamics of the near-Earth magnetotail associated with substorms during a period of extended southward interplanetary magnetic field is studied using a three-dimensional (3-D) global hybrid simulation model that includes both the dayside and nightside magnetosphere, for the first time, with physics from the ion kinetic to the global Alfvénic convection scales. It is found that the dayside reconnection leads to the penetration of the dawn-dusk electric field through the magnetopause and thus a thinning of the plasma sheet, followed by the magnetotail reconnection with 3-D, multiple flux ropes. Ion kinetic physics is found to play important roles in the magnetotail dynamics, which leads to the following results: (1) Hall electric fields in the thin current layer cause a systematic dawnward ion drift motion and thus a dawn-dusk asymmetry of the plasma sheet with a higher (lower) density on the dawnside (duskside). Correspondingly, more reconnection occurs on the duskside. Bidirectional fast ions are generated due to acceleration in reconnection, and more high-speed earthward flow injections are found on the duskside than the dawnside. Such finding of the dawn-dusk asymmetry is consistent with recent satellite observations. (2) The injected ions undergo the magnetic gradient and curvature drift in the dipole-like field, forming a ring current. (3) Ion particle distributions reveal multiple populations/beams at various distances in the tail. (4) Dipolarization of the tail magnetic field takes place due to the pileup of the injected magnetic fluxes and thermal pressure of injected ions, where the fast earthward flow is stopped. Oscillation of the dipolarization front is developed at the fast-flow braking, predominantly on the dawnside. (5) Kinetic compressional wave turbulence is present around the dipolarization front. The cross-tail currents break into small-scale structures with k ⟂ i ∼ 1, where k ⟂ is the perpendicular wave number. A sharp dip of magnetic field strength is seen just in front of the sharp rise of the magnetic field at the dipolarization front, mainly on the duskside. (6) A shear flow-type instability is found on the duskside flank of the ring current plasma, whereas a kinetic ballooning instability appears on the dawnside. (7) Shear Alfvén waves and compressional waves are generated from the tail reconnection, and they evolve into kinetic Alfvén waves in the dipole-like field region. Correspondingly, multiple field-aligned current filaments are generated above the auroral ionosphere.Geomagnetic substorms are one of the most important global-scale dynamic processes in the magnetosphere. Through the substorm, solar wind energy transmitted from the dayside magnetopause can be released from the magnetotail and injected into the high-latitude ionosphere. Since storms/substorms are conducive to strong particle injections from the tail plasma sheet and variations in the electromagneti...

Magnetotail reconnection and related phenomena (e.g., flux ropes, dipolarizing flux bundles, flow bursts, and particle injections) occur more frequently on the duskside than on the dawnside. Because this asymmetry can directly result in dawn‐dusk asymmetric space weather effects, uncovering its physical origin is important for better understanding, modeling, and prediction of the space weather phenomena. However, the cause of this pervasive asymmetry is unclear. Using three‐dimensional global hybrid simulations, we demonstrate that the Hall physics in the magnetotail current sheet is responsible for the asymmetry. The current sheet thins progressively under enhanced global convection; when its thickness reaches ion kinetic scales, some ions are decoupled from the magnetized electrons (the Hall effect). The resultant Hall electric field Ez is directed toward the neutral plane. The Hall effect is stronger (grows faster) on the duskside; i.e., more ions become unmagnetized there and do not comove with the magnetized dawnward Ez × Bx drifting electrons, thus creating a larger additional cross‐tail current intensity jy (in addition to the diamagnetic current) on the duskside, compared to the dawnside. The stronger Hall effect strength on the duskside is controlled by the higher ion temperature, thinner current sheet, and smaller normal magnetic field Bz there. These asymmetric current sheet properties are in turn controlled by two competing processes that correspond to the Hall effect: (1) the dawnward E × B drift of the magnetic flux and magnetized ions and electrons and (2) the transient motion of the unmagnetized ions which do not execute E × B drift.

[1] Magnetopause reconnection is investigated with our 3-D self-consistent global hybrid simulation model. The magnetic configuration and evolution of Flux Transfer Events (FTEs) and the associated ion density and ion velocity distribution at various locations on the magnetopause are investigated. The results reveal the following. (1) Multiple X lines are formed during the magnetopause reconnection, which lead to both FTEs and quasi-steady-type reconnection under a steady solar wind condition. The resulting bipolar signature of local normal magnetic field of FTEs is consistent with satellite observations. (2) A greater-than-20% plasma temperature rise is seen at the center of a FTE, compared to that of the upstream plasma in the magnetosheath. The temperature enhancement is mainly in the direction parallel to the magnetic field because of the mixing of ion beams. (3) Flux ropes that lead to FTEs form between X lines of finite lengths and evolve relatively independently. The ion density is enhanced within FTE flux ropes because of the trapped particles, leading to a filamentary global density. (4) Different from the previous understanding based on the asymmetric density across the magnetopause, a quadrupole magnetic field signature associated with the Hall effects is found to be present around FTEs.

[1] Two-dimensional hybrid simulations are used to investigate how fast-mode compressional waves incident on a magnetopause current layer mode convert both linearly and nonlinearly to short wavelength (k ? r i ∼ 1) kinetic Alfvén waves near the Alfvén resonance surface. The background magnetic fields on both sides of the current layer are parallel to each other and perpendicular to the magnetopause normal, corresponding to a northward interplanetary magnetic field. The simulations are performed in a 2-D plane (xz), where x is normal to the magnetopause and z is tilted by an angle, , relative to the magnetic field. We examine how the mode conversion depends on wave frequency w 0 , wave vector, Alfvén velocity profile (particularly the magnetopause width, D 0 ), ion b in the magnetosheath, electron-to-ion temperature ratio, and incident wave amplitude. Kinetic effects resolve the resonance, and KAWs radiate back to the magnetosheath side of the current layer. The compressional wave absorption rate is estimated and compared with linear theory. Unlike the prediction from low-frequency theory of the Alfvén resonance, KAWs are also generated in cases with = 0°, provided w 0 > 0.1W 0 , with W 0 being the ion cyclotron frequency in the magnetosheath. As the incident wave amplitude is increased, several nonlinear wave properties are manifested in the mode conversion process. Harmonics of the driver frequency are generated. As a result of nonlinear wave interaction, the mode conversion region and its spectral width are broadened. The nonlinear waves provide a significant transport of momentum across the magnetopause and are associated with significant ion heating in the resonant region.