HR: 1340h
AN: SH53A-1256    [Abstracts]
TI: Microscale Physics at Earth's Bow Shock: Cluster Observations of Electrostatic Solitary Waves
AU: * Pickett, J S
EM: pickett@uiowa.edu
AF: The University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Chen, L
SH53A-1256 AF: The University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Santolik, O
SH53A-1256 AF: The University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Santolik, O
SH53A-1256 AF: Charles University, Faculty of Mathematics and Physics, Prague, 18000 Czech Republic
AU: Swanner, J M
SH53A-1256 AF: The University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Lakhina, G S
SH53A-1256 AF: Indian Institute of Geomagnetism, Dr. Nanabhai Moos Marg, Colaba, Mumbai, 400 005 India
AU: Tsurutani, B
SH53A-1256 AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Gurnett, D A
SH53A-1256 AF: The University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Lucek, E
SH53A-1256 AF: The Blackett Laboratory, Imperial College, London, SWZ 2BZ United Kingdom
AB: A survey of the Electrostatic Solitary Waves (ESW) observed by the Cluster Wideband (WBD) Plasma Wave Receiver during several crossings of Earth's bow shock has resulted in some unexpected new results. Depending on various factors, including the bow shock normal angle and the upstream beta and Mach numbers, ESW are observed with differing characteristics across the transition region from upstream to downstream and under some circumstances are nearly totally absent across this region. In addition, in some cases the amplitudes of the solitary waves are directly related to the magnetic field strength. One of the most surprising results of the Cluster WBD survey is that there are distinctly two different populations of ESW at bow shock crossings which have been revealed through analyzing nearly 6,000 detections of ESW observed at Earth's bow shock. One population, which is the most numerous, has pulse time durations greater than 0.2 ms and an occurrence probability that peaks when the electric field antenna making the measurement is at 90 degrees to the magnetic field. The other lesser population has pulse durations less than 0.2 ms and a double-peaked, highest occurrence probability at antenna angles of 15-85 and 95-165 degrees to the magnetic field (with angles of 0-15 and 165-180 degrees probably being under sampled). By contrast, the magnetosheath favors almost exclusively the latter population. We conclude that the major population is most likely associated with ion dynamics due to the longer time duration of the ESW pulses and their detection perpendicular to the magnetic field, whereas the lesser population is related to electron dynamics due to the shorter time durations and detection at angles other than 90 degrees. Some possible generation mechanisms for the ESW observed at the bow shock are explored, as well as the possible role of ESW in bow shock processes.
DE: 4455 Nonlinear waves, shock waves, solitons (0689, 2487, 3280, 3285, 4275, 6934, 7851, DE: 7815 Electrostatic structures
DE: 7839 Nonlinear phenomena (4400, 6944)
DE: 7851 Shock waves (4455)
DE: 7852 Solitons and solitary waves (4455)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005