Frequency-dependent modulation of whistler-mode waves by density irregularities during the recovery phase of a geomagnetic storm

Liu, Xu; Gu, Wenyao; Xia, Zhiyang; Chen, Lunjin; Horne, Richard ORCID: https://orcid.org/0000-0002-0412-6407. 2021 Frequency-dependent modulation of whistler-mode waves by density irregularities during the recovery phase of a geomagnetic storm. Geophysical Research Letters, 48 (16), e2021GL093095. 10, pp. 10.1029/2021GL093095

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Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1029/2021GL093095
ISSN:	0094-8276
Date made live:	30 Jul 2021 12:47 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/529717

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