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Equatorial electromagnetic emission with discrete spectra near harmonics of oxygen gyrofrequency during magnetic storm
Author(s) -
Liu H.,
Kokubun S.,
Hayashi K.
Publication year - 1994
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 - 10.1029/93gl02836
Subject(s) - ring current , plasmasphere , physics , magnetic field , ion , spectral line , ionosphere , geomagnetic storm , extremely low frequency , magnetosphere , satellite , harmonics , atomic physics , atmospheric sciences , electric field , geophysics , computational physics , solar wind , astronomy , voltage , quantum mechanics
Equatorial electromagnetic ELF emissions at a frequency range around the oxygen ion gyrofrequency were observed in the low altitude plasmasphere (L = 1.5∼2.5) during magnetic storms with high activity of the ring current by triaxial search coil and single component electric field instruments on board the Akebono satellite. We find that a particular type of the ELF emissions occur with a multi‐band spectral structure around the local gyrofrequency ( F o + ) of the oxygen ion ( O + ) during the main phase of magnetic storm. Our finding includes the following; The multi‐band emissions are localized in the morning sector and often consist of several spaced frequency bands closely related the local gyro‐harmonics of oxygen ion ( O + ) with a fundamental frequency of F o + or 2 F o + . The frequency of each band is dependent on the local magnetic field variation along the satellite orbit and the spacing between the bands is almost equal to F o + or 2 F o + . It is suggested that emissions are generated by terrestrial oxygen ion composing the ring current area during the main phase of magnetic storm.