Van Allen Probes, THEMIS, GOES, and Cluster Observations of EMIC waves, ULF pulsations, and an electron flux dropout

TitleVan Allen Probes, THEMIS, GOES, and Cluster Observations of EMIC waves, ULF pulsations, and an electron flux dropout
Publication TypeJournal Article
Year of Publication2016
AuthorsSigsbee, K, Kletzing, CA, Smith, CW, MacDowall, R, Spence, H, Reeves, G, Blake, JB, Baker, DN, Green, JC, Singer, HJ, Carr, C, ík, O
JournalJournal of Geophysical Research: Space Physics
Date Published01/2016
KeywordsDst Effect; Electron Flux Dropouts; EMIC waves; magnetopause shadowing; ULF Pulsations; Van Allen Probes
AbstractWe examined an electron flux dropout during the 12–14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, THEMIS-A (P5), Cluster 2, and Geostationary Operational Environmental Satellite (GOES) 13, 14, and 15. The electron fluxes for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 hours from 12–14 November. For energies of 0.8 MeV, the GOES satellites observed two shorter intervals of reduced electron fluxes. The first interval of reduced 0.8 MeV electron fluxes on 12–13 November was associated with an interplanetary shock and a sudden impulse. Cluster, THEMIS, and GOES observed intense He+ EMIC waves from just inside geosynchronous orbit out to the magnetopause across the dayside to the dusk flank. The second interval of reduced 0.8 MeV electron fluxes on 13–14 November was associated with a solar sector boundary crossing and development of a geomagnetic storm with Dst < −100 nT. At the start of the recovery phase, both the 0.8 and 2.0 MeV electron fluxes finally returned to near pre-storm values, possibly in response to strong ultra-low frequency (ULF) waves observed by the Van Allen Probes near dawn. A combination of adiabatic effects, losses to the magnetopause, scattering by EMIC waves, and acceleration by ULF waves can explain the observed electron behavior.
URLhttp://doi.wiley.com/10.1002/2014JA020877
DOI10.1002/2014JA020877
Short TitleJ. Geophys. Res. Space Physics


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