Formation of Banded Chorus Waves by Propagation From Multiple Sources

Abstract

AbstractChorus waves are electromagnetic emissions in the magnetosphere and play a crucial role in energetic electron dynamics. Observations show that these waves often exhibit a two‐band structure with a power gap near half the electron cyclotron frequency. However, the mechanism behind this gap remains an open question, despite the existence of multiple theories. Here we propose a model to explain the banded structure by the different propagation properties of the lower and upper band waves within a density crest. This requires independent sources for lower and upper band waves, and unducted propagation of upper band waves to the observing location. The model naturally generates a gap near half the electron cyclotron frequency and can be extended to explain lower‐band‐only, upper‐band‐only, and no‐gap whistler waves. The model calls for further research on density irregularities in the magnetosphere and their effects on shaping wave properties.