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EMIC wave spatial and coherence scales as determined from multipoint Van Allen Probe measurements
Author(s) -
Blum L. W.,
Agapitov O.,
Bonnell J. W.,
Kletzing C.,
Wygant J.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl068799
Subject(s) - amplitude , physics , coherence (philosophical gambling strategy) , computational physics , scattering , spacecraft , phase (matter) , emic and etic , van allen probes , optics , van allen radiation belt , astronomy , plasma , magnetosphere , nuclear physics , quantum mechanics , sociology , anthropology
Electromagnetic ion cyclotron (EMIC) waves can provide a strong source of energetic electron pitch angle scattering. These waves are often quite localized, thus their spatial extent can have a large effect on their overall scattering efficiency. Using measurements from the dual Van Allen Probes, we examine four EMIC wave events observed simultaneously on the two probes at varying spacecraft separations. Correlation of both the wave amplitude and phase observed at both spacecraft is examined to estimate the active region and coherence scales of the waves. We find well‐correlated wave amplitude and amplitude modulation across distances spanning hundreds to thousands of kilometers. Phase coherence persisting 30–60 s is observable during close conjunction events but is lost as spacecraft separations exceed ~1 Earth Radii.