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Effect of parallel refraction on magnetospheric upper hybrid waves
Author(s) -
Engel John,
Kennel Charles F.
Publication year - 1984
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 - 10.1029/gl011i009p00865
Subject(s) - physics , lower hybrid oscillation , amplitude , geophysics , equator , earth's magnetic field , magnetic dip , computational physics , magnetosphere , refraction , ionosphere , ray tracing (physics) , magnetic field , plasma , electron density , wave propagation , optics , latitude , electromagnetic electron wave , quantum mechanics , astronomy
Large amplitude (⩾10 mV/m) electrostatic plasma waves near the upper hybrid (UH) frequency have been observed from 0° to 50° magnetic latitude (MLAT) during satellite plasma‐pause crossings. A three‐dimensional numerical ray tracing calculation, based on an electron distribution measured during a GEOS 1 dayside intense upper hybrid wave event, suggests how UH waves might achieve such large amplitudes away from the geomagnetic equator. Refractive effects largely control the wave amplification and, in particular, the unavoidable refraction due to parallel geomagnetic field gradients restricts growth to levels below those observed. However, a cold electron density gradient parallel to the field can lead to upper hybrid wave growth that can account for the observed emission levels.