HR: 13:45h
AN: SM23C-01 INVITED     [Abstracts]
TI: Cluster and Double Star Observations of Earth's Bow Shock and Upstream Region
AU: * Parks, G K
EM: parks@ssl.berkeley.edu
AF: Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 United States
AU: Lee, E
EM: eslee@ssl.berkeley.edu
AF: Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 United States
AU: Mozer, F
EM: fmozer@ssl.berkeley.edu
AF: Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 United States
AU: Wilber, M
EM: wilber@ssl.berkeley.edu
AF: Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 United States
AU: Lucek, E
EM: e.lucek@ic.ac.uk
AF: The Blackett Laboratory, Imperial College, London, xxxxx United Kingdom
AU: Dandouras, I
EM: dandouras@cesr.fr
AF: CESR, Paul Sabatier University, Toulouse, yyyyy France
AU: Reme, H
EM: reme@cesr.fr
AF: CESR, Paul Sabatier University, Toulouse, yyyyy France
AU: Cao, J B
EM: jbcao@center.cssar.ac.cn
AF: CSSAR, Academy of Sciences, Peking, zzzzz China
AB: The bow shock and upstream solar wind are extremely dynamic. A portion of the solar wind is reflected off the bow shock and travel back upstream. Magnetosheath particles also travel upstream on interplanetary magnetic field that connects to the bow shock. These backstreaming particles disturb the solar wind, excite instabilities and produce complex structures. We report novel observations of a class of ion density depletions that have durations of ~20s but as short as 8s. They are ubiquitous and seen out to Cluster apogee distance of ~19 RE. The temperature in the ion holes is a few million oK and the density can fall below the instrument detection threshold (~0.01/cc). The shapes are symmetric with both edges slightly elevated or highly asymmetric with only one edge elevated. The ion holes are accompanied by similarly shaped magnetic holes whose interior intensity is considerably reduced and fluctuating but at the edges highly enhanced and shock-like as in short, large-amplitude magnetic structures (SLAMS). 3D analysis shows the ion holes have dimensions of about a gyroradius of 4 keV protons and convecting with the solar wind. The electric fields at the edges are bipolar and the accompanying magnetic field undergoes either rotation or compression. These ion holes may be a previously unresolvable, early-development stage of the much more rare hot diamagnetic cavity structures or hot flow anomalies. The most likely theoretical explanations for these ion holes is that they are solitary Alfvenic structures produced by the nonlinear steepening of Alfven waves and evolving into coherent structures.
DE: 2109 Discontinuities (7811)
DE: 4455 Nonlinear waves, shock waves, solitons (0689, 2487, 3280, 3285, 4275, 6934, 7851, DE: 7851 Shock waves (4455)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005