Origin of Electron Boomerang Stripes: Localized ULF Wave‐Particle Interactions

Geophysical Research Letters

et al. 2021

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Section: Case On September 17 2013supporting

confidence: 80%

Section: Discussion and Summarymentioning

confidence: 99%

Origin of Electron Boomerang Stripes: Statistical Study

Zhao

Hao

Geophysical Research Letters

et al. 2021

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“…Keeping these in mind, the generalized drift resonance theory of particles' interaction with localized ULF waves are applicable for the event mentioned in and for the pitch angle evolution of "Boomerang-shaped" by Hao et al MagEIS-A [Zhao et al, 2020].…”

Section: Generalized Drift Resonance With Localized Ulf Waves: "Boomerang" Pitch Angle Distributionmentioning

confidence: 99%

Magnetospheric Response to Solar Wind Forcing: ULF Wave – Particle Interaction Perspective

2021

Preprint

Abstract. Solar wind forcing, e.g. interplanetary shock and/or solar wind dynamic pressure pulses impact on the Earth’s magnetosphere manifests many fundamental important space physics phenomena including producing electromagnetic waves, plasma heating and energetic particle acceleration. This paper summarizes our present understanding of the magnetospheric response to solar wind forcing in the aspects of radiation belt electrons, ring current ions and plasmaspheric plasma physics based on in situ spacecraft measurements, ground-based magnetometer data, MHD and kinetic simulations. Magnetosphere response to solar wind forcing, is not just a “one-kick” scenario. It is found that after the impact of solar wind forcing on the Earth’s magnetosphere, plasma heating and energetic particle acceleration started nearly immediately and could last for a few hours. Even a small dynamic pressure change of interplanetary shock or solar wind pressure pulse can play a non-negligible role in magnetospheric physics. The impact leads to generate series kind of waves including poloidal mode ultra-low frequency (ULF) waves. The fast acceleration of energetic electrons in the radiation belt and energetic ions in the ring current region response to the impact usually contains two contributing steps: (1) the initial adiabatic acceleration due to the magnetospheric compression; (2) followed by the wave-particle resonant acceleration dominated by global or localized poloidal ULF waves excited at various L-shells. Generalized theory of drift and drift-bounce resonance with growth or decay localized ULF waves has been developed to explain in situ spacecraft observations. The wave related observational features like distorted energy spectrum, boomerang and fishbone pitch angle distributions of radiation belt electrons, ring current ions and plasmaspheric plasma can be explained in the frame work of this generalized theory. It is worthy to point out here that poloidal ULF waves are much more efficient to accelerate and modulate electrons (fundamental mode) in the radiation belt and charged ions (second harmonic) in the ring current region. The results presented in this paper can be widely used in solar wind interacting with other planets such as Mercury, Jupiter, Saturn, Uranus and Neptune, and other astrophysical objects with magnetic fields.

“…Angular distance between the satellite and the origin of boomerang stripes could also be derived from the drifting time t(α)−t 0 . Please check our companion paper (Zhao et al, 2020) for technical details and validations from both simulations and multisatellite observations of PA-TOF method. Figure 4 (left) gives the origins of boomerang stripes in R1 estimated by PA-TOF method.…”

Section: Boomerang Stripes At the Lower Resonant Bandmentioning

confidence: 99%

“…Similar formulas have been utilized to model the impact of spatial distribution (Li et al, 2017) and time evolution (Zhou et al, 2016) on the electrons' drift resonance with ULF waves. Spatial envelope in the form of von Mise function does not lead to significant difference in electron flux patterns in comparison with a boxcar envelope (e.g., Hao et al, 2017;Zhao et al, 2020). With such a set of equations, wave form composed by a global low m wave and a localized moderate m wave has been defined.…”

Section: Appendix A: Electrons' Energy Gain From Ulf Wave Field Alongmentioning

confidence: 99%

Simultaneous Observations of Localized and Global Drift Resonance

Hao

Zhao

Geophysical Research Letters

et al. 2020

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In this study, we present Van Allen Probe observations showing that seed (hundreds of keV) and core ( ≳ 1 MeV) electrons can resonate with ultra‐low‐frequency (ULF) wave modes with distinctive m values simultaneously. An unusual electron energy spectrogram with double‐banded resonant structure was recorded by energetic particle, composition, and thermal plasma (ECT)‐magnetic electron ion spectrometer (MagEIS) and, meanwhile, boomerang stripes in pitch angle spectrogram appeared at the lower energy band. A localized drift resonance with m = 10 wave component was responsible for the resonant band peaked at ∼200 keV while a global drift resonance with m = 3 component gave rise to the upper band resonance peaked at ∼1 MeV. Time‐Of‐Flight on boomerang stripes suggested that the localized drift resonance with ∼200 keV electrons was confined within the plasmaspheric plume. Electron flux modulations were reproduced by numerical simulations in good consistency with the observations, supporting the scenario that localized and global drift resonance could coexist in the outer belt electron dynamics simultaneously.