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Externally driven plasmaspheric ULF waves observed by the Van Allen Probes


Metadata FieldValueLanguage
dc.contributorKyungguk Min, kmin@auburn.eduen_US
dc.creatorTakashashi, Kazue
dc.creatorMin, Kyungguk
dc.creatorMacDowall, Robert
dc.date.accessioned2020-06-05T19:29:10Z
dc.date.available2020-06-05T19:29:10Z
dc.date.created2015-01
dc.identifier10.1002/2014JA020373en_US
dc.identifier.urihttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014JA020373@10.1002/(ISSN)2169-9402.VANALLEN1en_US
dc.identifier.urihttp://hdl.handle.net/11200/49857
dc.description.abstractWe analyze data acquired by the Van Allen Probes on 8 November 2012, during a period of extended low geomagnetic activity, to gain new insight into plasmaspheric ultralow frequency (ULF) waves. The waves exhibited strong spectral power in the 5-40 mHz band and included multiharmonic toroidal waves visible up to the eleventh harmonic, unprecedented in the plasmasphere. During this wave activity, the interplanetary magnetic field cone angle was small, suggesting that the waves were driven by broadband compressional ULF waves originating in the foreshock region. This source mechanism is supported by the tailward propagation of the compressional magnetic field perturbations at a phase velocity of a few hundred kilometers per second that is determined by the cross-phase analysis of data from the two spacecraft. We also find that the coherence and phase delay of the azimuthal components of the magnetic field from the two spacecraft strongly depend on the radial separation of the spacecraft and attribute this feature to field line resonance effects. Finally, using the observed toroidal wave frequencies, we estimate the plasma mass density for L = 2.6-5.8. By comparing the mass density with the electron number density that is estimated from the spectrum of plasma waves, we infer that the plasma was dominated by H+ ions and was distributed uniformly along the magnetic field lines. The electron density is higher than the prediction of saturated plasmasphere models, and this super saturated plasmasphere and the uniform ion distribution are consistent with the low geomagnetic activity that prevailed.en_US
dc.formatPDFen_US
dc.publisherAMER GEOPHYSICAL UNIONen_US
dc.relation.ispartofJOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICSen_US
dc.relation.ispartofseries2169-9380en_US
dc.subjectULF waves; plasmasphere; multispacecraft observationen_US
dc.subjectGEOMAGNETIC-FIELD LINES; PC 3-4 PULSATIONS; ELECTRON-DENSITY; BOW SHOCK; STATISTICAL-ANALYSIS; INNER MAGNETOSPHERE; MAGNETIC PULSATIONS; HARMONIC STRUCTURE; RADIAL DIFFUSION; MASS DENSITYen_US
dc.titleExternally driven plasmaspheric ULF waves observed by the Van Allen Probesen_US
dc.typeTexten_US
dc.type.genreJournal Article, Academic Journalen_US
dc.citation.volume120en_US
dc.citation.issue1en_US
dc.citation.spage526en_US
dc.citation.epage552en_US
dc.description.statusPublisheden_US
dc.creator.orcid0000-0002-2095-8529en_US

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