Global Survey and Empirical Model of Fast Magnetosonic Waves Over Their Full Frequency Range in Earth's Inner Magnetosphere

TitleGlobal Survey and Empirical Model of Fast Magnetosonic Waves Over Their Full Frequency Range in Earth's Inner Magnetosphere
Publication TypeJournal Article
Year of Publication2019
AuthorsMa, Q, Li, W, Bortnik, J, Kletzing, CA, Kurth, WS, Hospodarsky, GB, Wygant, JR
JournalJournal of Geophysical Research: Space Physics
Volume124
Issue12
Pagination10270 - 10282
Date Published12/2019
ISSN2169-9380
KeywordsEmpirical Fitting; Global Survey; magnetosonic waves; Van Allen Probes; Van Allen Probes observation
AbstractWe investigate the global distribution and provide empirical models of fast magnetosonic waves using the combined observations by the magnetometer and waveform receiver on board Van Allen Probes. The magnetometer measurements of magnetosonic waves indicate a significant wave power within the frequency range from the helium gyrofrequency to 20 Hz at L ≥ 4 in the afternoon sector, both inside and outside the plasmapause. The waveform receiver measurements indicate a significant wave power from 20 Hz to the lower hybrid resonance frequency at L ≤ 5.5 near the dayside outside the plasmapause or in the afternoon sector inside the plasmapause. The sum of the wave powers from the two instruments provides the wave power distribution over the complete frequency range. The most significant root‐mean‐square wave amplitude of magnetosonic waves is typically 100–200 pT inside or outside the plasmapause with a magnetic local time coverage of 30–50% during geomagnetically active times when AE* > 500 nT. The magnetosonic wave frequency increases with decreasing L shell following the trend of the proton gyrofrequency outside the plasmapause, indicating a close relation with the local wave generation. Inside the plasmapause, the dependence of wave frequency on L shell is weaker, and the wave frequency is more stable across L shells, indicating the wave propagation effects from the source located at higher L shells. We have performed polynomial fits of the global magnetosonic wave distribution and wave frequency spectra, which are useful in future radiation belt simulations.
URLhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027407
DOI10.1029/2019JA027407
Short TitleJ. Geophys. Res. Space Physics


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