HR: 0830h
AN: SM41B-0567    [PDF]
TI: Widespread Electrostatic ion Cyclotron/ ion Acoustic Turbulence Above Auroral Acceleration Region; CLUSTER Observations
AU: * Backrud, M
EM: marie@irfu.se
AF: Swedish Institute of Space Physics, Box 537, Uppsala, 75121 Sweden
AU: Wahlund, J
EM: jwe@irfu.se
AF: Swedish Institute of Space Physics, Box 537, Uppsala, 75121 Sweden
AU: Andr\'{e}, M
EM: ma@irfu.se
AF: Swedish Institute of Space Physics, Box 537, Uppsala, 75121 Sweden
AU: Balogh, A
EM: a.balogh@ic.ac.uk
AF: The Blackett Laboratory, Imperial College, Prince Consort Road, London, SW7 2BW United Kingdom
AU: Buchert, S
EM: sb@irfu.se
AF: Swedish Institute of Space Physics, Box 537, Uppsala, 75121 Sweden
AU: Cornilleau, N
EM: Nicole.cornilleau@cetp.ipsl.fr
AF: CETP/CNRS, University of Versailles Saint Quentin, 10-12 Av. De l Europe, V\'{e}lizy, 78140
AU: Vaivads, A
EM: andris@irfu.se
AF: Swedish Institute of Space Physics, Box 537, Uppsala, 75121 Sweden
AB: We present CLUSTER observations based on a study of broadband ELF emissions above the auroral oval at altitudes around $\sim$ 4.5 $R_E$. The study focuses on the parallel electric field with the aim to identify the different emissions involved. We have found different emissions sorted by the ratio $\delta E_{\parallel}/\delta E_{\perp}$. No associated magnetic field component has been detected indicating electrostatic emissions. The numerical package WHAMP, solving the dispersion relation, shows that all emissions exist on the so-called ion acoustic dispersion surface, but with different wave vectors. For the event presented here, we have also identified dispersive Alfv\'{e}n waves at lower frequencies with a period well correlated with the most intensive emissions in the broadband region, which indicate that dispersive Alfv\'{e}n waves can trigger the electrostatic emissions at frequencies above the proton gyrofrequency.
DE: 2471 Plasma waves and instabilities
DE: 2483 Wave/particle interactions
DE: 2487 Wave propagation (6934)
DE: 2704 Auroral phenomena (2407)
DE: 2772 Plasma waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting