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Spatial localization and ducting of EMIC waves: Van Allen Probes and ground‐based observations
Author(s) -
Mann I. R.,
Usanova M. E.,
Murphy K.,
Robertson M. T.,
Milling D. K.,
Kale A.,
Kletzing C.,
Wygant J.,
Thaller S.,
Raita T.
Publication year - 2014
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 - 10.1002/2013gl058581
Subject(s) - van allen probes , plasmasphere , physics , geophysics , van allen radiation belt , elliptical polarization , magnetometer , polarization (electrochemistry) , earth's magnetic field , computational physics , ionosphere , magnetosphere , geology , geodesy , astrophysics , magnetic field , optics , linear polarization , laser , chemistry , quantum mechanics
On 11 October 2012, during the recovery phase of a moderate geomagnetic storm, an extended interval (> 18 h) of continuous electromagnetic ion cyclotron (EMIC) waves was observed by Canadian Array for Real‐time Investigations of Magnetic Activity and Solar‐Terrestrial Environment Program induction coil magnetometers in North America. At around 14:15 UT, both Van Allen Probes B and A (65° magnetic longitude apart) in conjunction with the ground array observed very narrow (ΔL ~ 0.1–0.4) left‐hand polarized EMIC emission confined to regions of mass density gradients at the outer edge of the plasmasphere at L ~ 4. EMIC waves were seen with complex polarization patterns on the ground, in good agreement with model results from Woodroffe and Lysak (2012) and consistent with Earth's rotation sweeping magnetometer stations across multiple polarization reversals in the fields in the Earth‐ionosphere duct. The narrow L‐widths explain the relative rarity of space‐based EMIC occurrence, ground‐based measurements providing better estimates of global EMIC wave occurrence for input into radiation belt dynamical models.