HR: 1400h
AN: SM33A-03    [Abstracts]
TI: A Model for Bipolar Electric Field Structures Parallel to the Magnetic Field Observed in Polar Ionosphere
AU: * Shi, J
EM: jkshi@center.cssar.ac.cn
AF: State Key Laboratory for Space Weather, CSSAR, Chinese Academy of Sciences, Beijing 100080, China
AU: Qureshi, N
EM: nouman@spaceweather.ac.cn
AF: State Key Laboratory for Space Weather, CSSAR, Chinese Academy of Sciences, Beijing 100080, China
AU: Torkar, K
EM: Klaustorkar@aoew.a.at
AF: Space Research Institute, Austrian Academy of Sciences, A-8042, Graz, Austria
AU: Dunlop, M
EM: mwdunlop@rl.ac.uk
AF: SSTD, Rutherford Appleton Laboratory, Chilton, Didcot, United Kingdom
AU: Liu, Z
EM: Liu@cssar.ac.cn
AF: State Key Laboratory for Space Weather, CSSAR, Chinese Academy of Sciences, Beijing 100080, China
AB: The bipolar electric field structures were observed in many space plasmas, such as the solar wind, magnetosheath, magnetotail, and the auroral zone. In this study, a physical model for the existence of the bipolar electric field structures propagating along the magnetic field line is established by deriving the "Sagdeev potential" from the magnetohydrodynamic (MHD) equations in a cylindrical coordinate system. The model shows that the bipolar electric field structure can develop not only from an ion acoustic wave, but also from an ion cyclotron wave when the Mach number and the initial electric field satisfy certain conditions. The polarity of the bipolar electric field structure can be oriented either negative to positive or the reverse polarity. According to the conditions in the auroral region, amplitude of the BEF structure can be varied from 35 to 330 mV/m, and its duration can be 7 ms to 23 ms. These predictions are in agreement with observation in the auroral region.
DE: 2149 MHD waves and turbulence (2752, 6050, 7836)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly