HR: 0800h
AN: SH51B-1203    [Abstracts]
TI: Structure of ion holes in the solar wind upstream of the bow shock
AU: * Lee, E
EM: eslee@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720 United States
AU: Parks, G K
EM: parks@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720 United States
AU: Wilber, M
EM: wilber@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720 United States
AU: Mozer, F
EM: fmozer@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720 United States
AU: Lucek, E A
EM: e.lucek@imperial.ac.uk
AF: Blackett Laboratory, Imperial College, London, SW7 2BW United Kingdom
AU: Dandouras, I
EM: iannis.dandouras@cesr.fr
AF: CESR, BP 4346, Toulouse, 31028 France
AU: Reme, H
EM: reme@cesr.fr
AF: CESR, BP 4346, Toulouse, 31028 France
AU: Cao, J B
EM: jbcao@center.cssar.ac.cn
AF: Center of Space Science and Applied Research, Chinese Academy of Sciences, Beijing, 100080 China
AB: Cluster has observed ion holes in the solar wind upstream of the bow shock. We will present detailed structure of the ion holes and their relation with the bow shock. The ion holes are characterized by the thermalized plasmas with the density lower than that of the surrounding plasmas. They are accompanied by magnetic holes. We have determined the boundary normal orientation and speed using the timing analysis of the 4 Cluster spacecrafts. The boundary normal orientations relative to the bow shock vary largely for different events. In some cases the boundary is quasi-parallel to the bow shock, so they intersect with each other. However, there are also the cases with the boundary quasi-perpendicular to the bow shock. This implies that the ion holes can be generated by different mechanisms, some of which are closely related with the bow shock, but the others not. At the edges of the ion holes the density and magnetic field strength are enhanced simultaneously showing shock-like features. For some events the enhanced magnetic field is almost purely compressional, but for the others it has rotation as well as compression. The speeds of the upstream and downstream edges are not same, which represents the ion hole is not a stationary structure. We will compare the properties of several different processes like hot flow anomalies, foreshock cavities, and other nonlinear processes with those of the ion holes. This may provide better insight on the generation mechanism of the ion holes.
DE: 2109 Discontinuities (7811)
DE: 2154 Planetary bow shocks
DE: 2164 Solar wind plasma
DE: 7852 Solitons and solitary waves (4455)
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005