Multipoint Measurement of Fine‐Structured EMIC Waves by Arase, Van Allen Probe A, and Ground Stations

We examined the growth and propagation of fine-structured electromagnetic ion cyclotron (EMIC) waves related to time-varying density irregularities using multipoint measurement data observed by Arase, Van Allen Probe A, two ground-based induction magnetometers (Gakona Dawson) during a field line conjunction event on April 18, 2019. analyzed wave obtained aforementioned spacecraft stations, found that appearance fine structures in EMIC clearly coincided with ambient electron magnetosphere, which can cause periodic waveguiding their propagation. Furthermore, we latitudinal widths activity region duct were ∼185 km less than 80 at an auroral altitude 100 km, respectively. also thermal heating ( eV/q) activity.