Observational Properties of Harmonic EMIC waves: Statistical Study

2024/12/20 by Shujie Gu, Gu, Shujie, Xu Liu +9
Engineering · #Acoustic Wave Resonator Technologies #FOS: Physical sciences #Machine Fault Diagnosis Techniques #Space Physics (physics.space-ph) #Structural Health Monitoring Techniques

paper · pdf · doi:10.48550/arxiv.2412.16124

openalex publication_date 2024/12/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Electromagnetic ion cyclotron (EMIC) waves are discrete electromagnetic emissions separated by multiple ion gyrofrequencies. Harmonic EMIC waves are defined as waves with a strong electric or magnetic field (or both) at the harmonics of the fundamental EMIC mode. In this paper, for the first time, we present a statistical study on harmonic EMIC waves by the Van Allen Probes. The EMIC waves are categorized into three types based on their harmonics: (1) fundamental mode only (without higher harmonics), (2) electrostatic (ES) harmonics, and (3) electromagnetic (EM) harmonics. Our statistical study shows that ES and EM harmonic EMIC waves predominantly occur on the dayside, outside the plasmasphere with L >5 and are associated with a low f_pe/f_ce, a high proton β_H, and a strong fundamental EMIC mode. The results will advance our understanding of harmonic EMIC waves and their generation mechanisms.

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