We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Prompt Appearance of Large‐Amplitude EMIC Waves Induced by Solar Wind Dynamic Pressure Enhancement and the Subsequent Relativistic Electron Precipitation.
- Authors
Yan, Yun; Yue, Chao; Ma, Qianli; Zhou, Xu‐Zhi; Zong, Qiu‐Gang; Fu, Haobo; Xie, Zi‐Kang; Yin, Ze‐Fan; Li, Yu‐Xuan
- Abstract
Electromagnetic ion cyclotron (EMIC) waves play an important role in relativistic electron dynamics. In this study, we find a large‐amplitude EMIC wave event induced by the prompt enhancement of solar wind dynamic pressure on 6 November 2015. These large‐amplitude EMIC waves are simultaneously observed by multiple satellites over 13 hr in magnetic local time (MLT) with a peak amplitude of ∼4 nT. Satellites at different locations observed different bands of EMIC waves, implying the importance of background plasma density in EMIC wave generation. Electron pitch angle distributions show obvious responses to EMIC wave activities. During EMIC wave appearance, the fluxes of relativistic electrons with pitch angles around 90° increase, while the fluxes of field‐aligned relativistic electrons decrease, showing distinct "bite‐out" signatures, indicating pitch angle scattering by EMIC waves, and the scattering efficiency depends on the amplitude and polarization of EMIC waves. Combined with phase space density profiles of electrons that are nearly constant at energies below the minimum resonant energy of electrons (Emin) but show dropout at energies above the Emin after EMIC wave activities, we conclude that large‐amplitude EMIC waves can cause rapid electron loss down to several hundred keV. In addition, simultaneous observations of hundreds of keV electron precipitation and tens of keV proton precipitation by Polar Operational Environmental Satellites near the region where EMIC waves are observed, provide direct evidence of relativistic electron precipitation caused by the large‐amplitude EMIC waves, ultimately driven by solar wind structures. Plain Language Summary: Solar wind dynamic pressure enhancement leads to the compression of the magnetopause, which could induce various plasma waves. Our study shows the prompt appearance of large‐amplitude EMIC waves after the impact of solar wind dynamic pressure enhancement. The excited EMIC waves are observed simultaneously by multiple satellites over 13 hr in magnetic local time. Different bands of EMIC waves are observed by satellites at different locations, which may be related to the background plasma density. During EMIC wave appearance, the fluxes of relativistic electrons with pitch angles around 90° increase, while the fluxes of field‐aligned relativistic electrons decrease, showing distinct "bite‐out" signatures, and the scattering efficiency depends on the amplitude and polarization of EMIC waves. Besides, phase space density profiles of electrons show that PSDs are nearly constant at energies below the Emin but show evident dropout at energies above the Emin, demonstrating that large‐amplitude EMIC waves can cause a rapid loss of electrons down to several hundred keV. In addition, solid evidence of strong relativistic electron precipitation driven by EMIC waves is provided by the low‐altitude Polar Operational Environmental Satellites near the region where EMIC waves are observed, which shows the simultaneous observations of hundreds of keV electron precipitation and tens of keV proton precipitation. Key Points: Multi‐point spacecraft observations indicate a close correlation between solar wind dynamic pressure enhancement and Electromagnetic ion cyclotron (EMIC) wave appearanceEMIC waves have a broad magnetic local time (MLT) coverage (∼13 hr) and are associated with anisotropic electron fluxesCompression‐induced EMIC waves cause phase space density dropout of sub‐MeV to MeV electrons and subsequent precipitation to the atmosphere
- Subjects
SOLAR wind; DYNAMIC pressure; RELATIVISTIC electrons; WIND pressure; ELECTRON density; PLASMA waves
- Publication
Journal of Geophysical Research. Space Physics, 2023, Vol 128, Issue 7, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2023JA031399