Frequency-Dependent Modulation of Whistler-mode Waves By Density Irregularities During the Recovery Phase of a Geomagnetic Storm

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Abstract
Abstract Density irregularities near the plasmapause are commonly observed and play an important role in whistler-mode wave excitation and propagation. In this study, we report a frequency-dependent modulation event of whistler-mode waves by background density irregularities during a geomagnetic storm. Higher-frequency whistler waves (near 0.5 fce, where fce is the equatorial electron cyclotron frequency) are trapped in the density trough regions due to the small refractive index near the parallel direction, while lower-frequency whistler waves (below 0.02 fce) are trapped in the density crest regions due to the refractive index maximum along the parallel direction. In addition to the modulation, we also find that, quantitatively, the wave amplitude of the higher- (lower-) frequency whistler-mode waves is anti-correlated (correlated) with the relative plasma density variation. Our study suggests the importance of density irregularity dynamics in controlling whistler-mode wave intensity, and thus radiation belt dynamics.
Notes
Year of Publication
2021
Journal
Geophysical Research Letters
Volume
n/a
Number
Number of Pages
e2021GL093095
Date Published
07/2021
URL
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021GL093095
DOI
https://doi.org/10.1029/2021GL093095