Fine structure embedded in whistler mode chorus wave packets: observations of Cluster and Van Allen Probes in the inner magnetosphere

0473466 - ÚFA 2017 FR eng A - Abstrakt
Santolík, Ondřej - Kolmašová, Ivana - Pickett, J. - Kurth, W. - Hospodarsky, G. B. - Gurnett, D. A. - Kletzing, C. A. - Bounds, S. R.
Fine structure embedded in whistler mode chorus wave packets: observations of Cluster and Van Allen Probes in the inner magnetosphere.
4th Cluster and THEMIS workshop: Book of abstracts. Paris: European Space Agency (ESA), 2017. s. 31.
[Cluster-THEMIS Workshop /4./. 07.11.2016-12.11.2016, Palm Springs]
Institucionální podpora: RVO:68378289
Klíčová slova: whistler mode chorus waves * Van Allen radiation belt * inner magnetosphere * cluster
Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech
http://themis.igpp.ucla.edu/events/CLUSTER_THEMIS_2016/Workshop_abstracts_v3.pdf

Electromagnetic whistler-mode chorus waves are among the most intense naturally
occurring emissions in the inner magnetosphere. Their amplitudes at hundreds of
Hz to several kHz frequencies can reach 1% of
the background magnetic field. These waves can play a significant role in the
process of local acceleration of relativistic electrons and they can therefore strongly
influence the dynamics of the outer Van Allen radiation belt.
Investigation of the nonlinear generation process of chorus is a subject of a
significant effort in theoretical studies and numerical simulations, aiming at
microphysics of wave-particle interactions. Assumptions of these studies need to be
constrained by in situ observations. We use measurements of the Wide Band Data
(WBD) instrument onboard Cluster spacecraft as well as measurements of the
Waves instrument of the Electric and Magnetic Field Instrument Suite and
Integrated Science (EMFISIS) onboard the Van Allen Probes to analyze intense
chorus A large data base of multicomponent and multipoint waveform data has been
collected by these instruments.
We use selected intervals of chorus and we determine the instantaneous
amplitudes, phases, frequencies, and wave vector directions of chorus waveforms.
Fine structure embedded in the chorus elements mainly reflects the simultaneous
presence of waves at different frequencies (sidebands) although separate wave
packets are also observed. The observed frequency differences (time scales of
subpackets) do not seem to scale with amplitude as does the theoretical trapping
frequency. Our results further show that peak values of the instantaneous amplitude
decrease with the distance fro
m the magnetic equator and with the time interval between peaks.
Trvalý link: http://hdl.handle.net/11104/0270581