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Wave emissions at half electron gyroharmonics in the equatorial plasmasphere region: CLUSTER observations and statistics

dc.contributor.authorEl-Lemdani Mazouz, F.
dc.contributor.authorRauch, J.L.
dc.contributor.authorDécréau, P.M.E.
dc.contributor.authorTrotignon, J.G.
dc.contributor.authorVallières, X.
dc.contributor.authorDarrouzet, F.
dc.contributor.authorCanu, P.
dc.contributor.authorSuraud, X.
dc.date2009
dc.date.accessioned2016-04-05T10:30:19Z
dc.date.available2016-04-05T10:30:19Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/3245
dc.descriptionIntense (n + 1/2) fce emissions are a common phenomenon observed in the terrestrial inner magnetosphere. One of their interests is their possible effect in the pitch angle scattering of plasmasheet keV-electron, leading to diffuse auroras. In this paper, we present CLUSTER's point of view about this topic, in the equatorial region of the plasmasphere, via a statistical study using 3 years of data. Spectral characteristics of these waves, which represent an important clue concerning their generation mechanism, are obtained using WHISPER data near perigee. Details on the wave spectral signature are shown in an event study, in particular their splitting in fine frequency bands. The orbit configuration of the four spacecraft offers a complete sampling on all MLT sectors. A higher occurrence rate of the emissions in the dawn sector and their confinement to the geomagnetic equator, pointed out in previous studies, are confirmed and described with additional details. The proximity of emission sites, both to the plasmapause layer and to the geomagnetic equator surface, seems to be of great importance in the behaviour of the (n + 1/2) fce wave characteristics. Our study indicates for the first time, that both the intensity of (n + 1/2) fce emissions, and the number of harmonic bands they cover, are increasing as the observation point is located further away outside from the plasmapause layer. Moreover, a study of the wave intensity in the first harmonic band (near 3/2 fce) shows higher amplitude for these emissions than previous published values, these emissions can play a role in the scattering of hot electrons. Finally, geomagnetic activity influence, studied via time series of the Dst index preceding observations, indicates that (n + 1/2) fce emission events are observed at CLUSTER position under moderate geomagnetic activity conditions, no specific Dst time variation being required. © 2008 COSPAR.
dc.languageeng
dc.titleWave emissions at half electron gyroharmonics in the equatorial plasmasphere region: CLUSTER observations and statistics
dc.typeArticle
dc.subject.frascatiPhysical sciences
dc.audienceScientific
dc.subject.freeCyclotrons
dc.subject.freeFrequency bands
dc.subject.freeGeomagnetism
dc.subject.freeHarmonic analysis
dc.subject.freeHot electrons
dc.subject.freeMagnetosphere
dc.subject.freeRockets
dc.subject.freeDiffuse aurora
dc.subject.freeElectron cyclotron harmonic waves
dc.subject.freeEmission sites
dc.subject.freeEquatorial regions
dc.subject.freeEvent studies
dc.subject.freeFirst harmonics
dc.subject.freeGeneration mechanisms
dc.subject.freeGeomagnetic activities
dc.subject.freeGeomagnetic equators
dc.subject.freeInner magnetospheres
dc.subject.freeObservation points
dc.subject.freePitch angles
dc.subject.freePlasma pauses
dc.subject.freePlasmasphere
dc.subject.freeSpectral characteristics
dc.subject.freeSpectral signatures
dc.subject.freeStatistical studies
dc.subject.freeTime series
dc.subject.freeTime variations
dc.subject.freeWave characteristics
dc.subject.freeWave emissions
dc.subject.freeWave intensities
dc.subject.freeElectrons
dc.source.titleAdvances in Space Research
dc.source.volume43
dc.source.issue2
dc.source.page253-264
Orfeo.peerreviewedYes
dc.identifier.doi10.1016/j.asr.2008.06.007
dc.identifier.scopus2-s2.0-58149234041


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