HR: 0800h
AN: SM11A-0309    [Abstracts]
TI: Evidence of quasi perpendicular shock front nonstationarity from CLUSTER data: comparative approach with numerical simulation results
AU: * Mazelle, C
EM: christian.mazelle@cesr.fr
AF: CESR / UPS-CNRS, 9, Avenue du Colonel Roche, Toulouse, 31400, France
AU: Lembege, B
EM: bertrand.lembege@cetp.ipsl.fr
AF: CETP UVSQ, 10/12, Avenue de l'Europe, Velizy, 78140, France
AU: Morgenthaler, A
EM: morgenthaler@cesr.fr
AF: CESR / UPS-CNRS, 9, Avenue du Colonel Roche, Toulouse, 31400, France
AU: Meziane, K
EM: karim@unb.ca
AF: Physics Department, University of New Brunswick, Fredericton, NB E3B5A3, Canada
AU: Horbury, T S
EM: t.horbury@imperial.ac.uk
AF: The Blackett Laboratory, Imperial College London, London, SW72BZ, United Kingdom
AU: Lucek, E A
EM: e.lucek@imperial.ac.uk
AF: The Blackett Laboratory, Imperial College London, London, SW72BZ, United Kingdom
AU: Dandouras, I
EM: dandouras@cesr.fr
AF: CESR / UPS-CNRS, 9, Avenue du Colonel Roche, Toulouse, 31400, France
AB: Both numerical simulations and experimental observations (CLUSTER) have evidenced that the front of quasi perpendicular shocks may be strongly stationary or nonstationary. Simulations have evidenced several different mechanisms responsible for this nonstationarity both on macro- (ion) and micro- scales and but no detailed comparison has been performed with experimental data until now. The fact that several mechanisms can coexist together make a clear diagnosis quite difficult. On the other hand, multi satellites CLUSTER mission reveals to be helpful for clarifying the situation. The present work focuses on experimental CLUSTER data where macroscale nonstationarity is evidenced and identified as being due to the shock front self reformation driven by the accumulation of reflected ions. Detailed analysis is performed based on many criteria accumulated from a collection of previous 1D and 2D PIC simulation (changes both in ramp-foot scales and typical changes in the local ion distribution function). In particular, it accounts the surprising experimental results where the shock ramp can be very thin and access to a few inertial electron lengths only. Present detailed results are also completed by an additional statistical analysis. These experimental data confirm that the shock front can be nonstationary and that the identified responsible process strongly competes with another self reformation process driven by nonlinear dispersive waves activity.
DE: 2154 Planetary bow shocks
DE: 2784 Solar wind/magnetosphere interactions
DE: 7846 Plasma energization
DE: 7851 Shock waves (4455)
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting