Whistler-Mode Waves Inside Short Large-Amplitude Magnetic Field Structures: Characteristics and Generation Mechanisms

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.