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- Title
Whistler‐Mode Waves Inside Short Large‐Amplitude Magnetic Field Structures: Characteristics and Generation Mechanisms.
- Authors
Bai, Shi‐Chen; Shi, Quanqi; Shen, Xiao‐Chen; Tian, Anmin; Zhang, Hui; Guo, Ruilong; Wang, Mengmeng; Degeling, Alexander W.; Bu, Yude; Zhang, Shuai; Ma, Xiao
- Abstract
Short large‐amplitude magnetic structures (SLAMS) frequently appear near the bow shock. Inside steepening SLAMS, whistler‐mode waves are coherently generated at their leading edges. These waves are crucial for electron dynamics, energy conversion and magnetic reconnection near the shock. Nevertheless, the characteristics and generation of the whistler‐mode waves inside SLAMS are still unclear. In this study, we conducted a statistical analysis of whistler‐mode waves within SLAMS near the Earth's bow shock to investigate their properties and generation mechanisms. We found that these waves are mainly excited by electron temperature anisotropy with 99% of them falling below the nonlinear resonant threshold. The combination of a low background magnetic field and intense steepening at SLAMS' leading edge makes it the main source region of whistler‐mode waves and may induce the nonlinear resonance of whistler‐mode waves. Plain Language Summary: On the quasi‐parallel side of the bow shock, ultra‐low frequency waves and nonlinear structures such as shocklets and SLAMS are commonly observed, which are crucial for the particle dynamics and energy conversion near the shock. Whistler‐mode waves are coherently generated at the leading edge or Earthward side of these nonlinear structures and may subsequently evolve into the shocklets. These waves are crucial for electron dynamics, energy dissipation and energy cascade near the shock. In addition, recent studies have discovered that the propagation of whistler‐mode waves can trigger magnetic reconnection processes inside SLAMS. Nevertheless, the characteristics and generation of the whistler‐mode waves inside SLAMS are still unclear. A comprehensive understanding of whistler‐mode waves inside SLAMS is still missing. In this paper, based on statistical results, we found that most of the whistler‐mode waves are locally generated and trapped inside the SLAMS. The nonlinear resonance condition of whistler‐mode waves is only satisfied at the leading edge of SLAMS with significant steepening. Key Points: Whistler‐mode waves are locally excited and trapped inside the SLAMSMost of the whistler‐mode are excited by electron temperature anisotropy resulting from SLAMS steepeningThe significant steepening seems essential for the nonlinear resonance of whistler‐mode waves at the leading edge of SLAMS
- Subjects
MAGNETIC structure; MAGNETIC fields; MAGNETIC reconnection; PARTICLE dynamics; ELECTRON temperature
- Publication
Journal of Geophysical Research. Space Physics, 2024, Vol 129, Issue 3, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2023JA032392