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

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    ElLemdani(2009).pdf (735.4Kb)
    Authors
    El-Lemdani Mazouz, F.
    Rauch, J.L.
    Décréau, P.M.E.
    Trotignon, J.G.
    Vallières, X.
    Darrouzet, F.
    Canu, P.
    Suraud, X.
    Show allShow less
    Discipline
    Physical sciences
    Subject
    Cyclotrons
    Frequency bands
    Geomagnetism
    Harmonic analysis
    Hot electrons
    Magnetosphere
    Rockets
    Diffuse aurora
    Electron cyclotron harmonic waves
    Emission sites
    Equatorial regions
    Event studies
    First harmonics
    Generation mechanisms
    Geomagnetic activities
    Geomagnetic equators
    Inner magnetospheres
    Observation points
    Pitch angles
    Plasma pauses
    Plasmasphere
    Spectral characteristics
    Spectral signatures
    Statistical studies
    Time series
    Time variations
    Wave characteristics
    Wave emissions
    Wave intensities
    Electrons
    Audience
    Scientific
    Date
    2009
    Metadata
    Show full item record
    Description
    Intense (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.
    Citation
    El-Lemdani Mazouz, F.; Rauch, J.L.; Décréau, P.M.E.; Trotignon, J.G.; Vallières, X.; Darrouzet, F.; Canu, P.; Suraud, X. (2009). Wave emissions at half electron gyroharmonics in the equatorial plasmasphere region: CLUSTER observations and statistics. , Advances in Space Research, Vol. 43, Issue 2, 253-264, DOI: 10.1016/j.asr.2008.06.007.
    Identifiers
    uri: https://orfeo.belnet.be/handle/internal/3245
    doi: http://dx.doi.org/10.1016/j.asr.2008.06.007
    scopus: 2-s2.0-58149234041
    Type
    Article
    Peer-Review
    Yes
    Language
    eng
    Links
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