HR: 0830h
AN: SM51C-0552 [PDF]
TI: A microscopic and nanoscopic view of storm-time chorus
AU: * Santolik, O
EM: ondrej.santolik@mff.cuni.cz
AF: Charles University, Faculty of Mathematics and Physics,
V Holesovickach 2, Prague, CZ-18000
Czech Republic
AU: * Santolik, O
EM: ondrej.santolik@mff.cuni.cz
AF: University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Gurnett, D A
EM: gurnett@space.physics.uiowa.edu
AF: University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Pickett, J S
EM: jsp@space.physics.uiowa.edu
AF: University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Parrot, M
EM: mparrot@cnrs-orleans.fr
AF: LPCE/CNRS, 3A, Av. de la Recherche Scientifique, Orleans, F-45071
France
AU: Cornilleau-Wehrlin, N
EM: nicole.cornilleau@cetp.ipsl.fr
AF: CETP, 10/12 Av. de l'Europe, Velizy, F-78140
France
AB:
We use multipoint measurements obtained by the Cluster
spacecraft to investigate intense whistler-mode chorus
emissions during the geomagnetic storms. The observations
were recorded close to the equatorial plane at a radial
distance of 4 Earth radii. We first show a ``microscopic view''
of spatio-temporal variations of the direction of the Poynting
flux. We investigate the central position of the chorus
source which fluctuates at time scales of minutes within
a few thousands km of the geomagnetic equator. We demonstrate
that estimates of the electromagnetic planarity can be used
to characterize the extent of the source region parallel to the
ambient magnetic field. We also show a ``nanoscopic view''
of discrete wave packets of chorus rising in frequency
between 1 and 4 kHz at a rate up to 20 kHz/s, and having
peak amplitudes above 20 mV/m. We study the fine structure
of subpackets embedded in the chorus wave packets.
This fine structure has a typical delay of a few milliseconds
between the two neighboring maxima of the wave amplitude,
while longer delays occur with a decreasing probability density.
UR: http://terezka.ufa.cas.cz/santolik/papers/agu2003
DE: 2730 Magnetosphere--inner
DE: 2772 Plasma waves and instabilities
DE: 7871 Waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting