Can EMIC triggered emissions be generated off the magnetic equatorial plane?

0473468 - ÚFA 2017 FR eng A - Abstrakt
Grison, Benjamin - Breuillard, H. - Santolík, Ondřej - Cornilleau-Wehrlin, N. - Hanzelka, Miroslav
Can EMIC triggered emissions be generated off the magnetic equatorial plane?
4th Cluster and THEMIS workshop: Book of abstracts. Paris: European Space Agency (ESA), 2017. s. 30.
[Cluster-THEMIS Workshop /4./. 07.11.2016-12.11.2016, Palm Springs]
Institucionální podpora: RVO:68378289
Klíčová slova: EMIC triggered emissions * EMIC waves * inner magnetosphere * cluster * THEMIS
Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech
http://themis.igpp.ucla.edu/events/CLUSTER_THEMIS_2016/Workshop_abstracts_v3.pdf

ElectroMagnetic Ion Cyclotron (EMIC) triggered emissions (TEs) result from
interaction between energetic protons (>1keV) and EMIC waves in the inner
magnetosphere and in the dayside regions. The frequency with time dispersion and
the high coherence level of the waves are characteristics of these emissions. They
play a role in proton precipitations and their influence can be stronger in larger
magnetospheres (at Saturn or Jupiter, for examples).
EMIC triggered emissions have been recently observed in situ by Cluster and
THEMIS spacecraft. Up to our knowledge all events are observed close to magnetic
equatorial plane, at magnetic latitudes (MLAT) lower than 15deg. The source region
has been found in the vicinity of the equatorial plane for all these events.
In the present study we focus on three distinct Cluster events. In each of this event
one or more EMIC triggered emissions are observed by one or more Cluster
spacecraft off the magnetic equatorial plane (> 20deg MLAT). One of these events is
of particular interest because many TEs occur at periodic time interval.
We first present a detailed polarization analysis of these waves. The magnetic
waveform (STAFF instrument data) is transformed into the Fourier space for a
study based on singular value decomposition (SVD) analysis. Unfortunately, the
Poynting flux orientation could not be established. Then we compare our results to
the observation of previous cases. In order to identify the source region we study
two possibilities: a source region at higher latitudes than the observations (and
particles orbiting in 'Shabansky' orbits) and a source region close to the magnetic
equatorial plane, as reported in previous studies. The results are completed with a
preliminary ray-tracing analysis.
Trvalý link: http://hdl.handle.net/11104/0270583