HR: 0800h
AN: SH31A-1166    [Abstracts]
TI: On the Generation of Rotational Discontinuities in the Solar Wind
AU: * Lyu, L
EM: lyu@jupiter.ss.ncu.edu.tw
AF: National Central University, Institute of Space Science, National Central University, Chung-Li, 320-01 Taiwan
AU: Chen, C
EM: ccchen@jupiter.ss.ncu.edu.tw
AF: National Central University, Institute of Space Science, National Central University, Chung-Li, 320-01 Taiwan
AU: Tsai, W
EM: tomo@jupiter.ss.ncu.edu.tw
AF: National Central University, Institute of Space Science, National Central University, Chung-Li, 320-01 Taiwan
AU: Lai, S
EM: lucky@jupiter.ss.ncu.edu.tw
AF: National Central University, Institute of Space Science, National Central University, Chung-Li, 320-01 Taiwan
AB: Magnetic hodogram of rotational discontinuities (RDs) observed in the solar wind are characterized by mixed magnetic polarity (Neugebauer, 1989). This type of magnetic hodogram is part of the nonlinear wave solutions obtained in our previous theoretical study. Unfortunately, previous simulation studies fail to reproduce this type of RDs from a circularized nonlinear Alfven wave. Our recent MHD simulation study of velocity-shear instability indicates that no vortex but nonlinear plane waves can be formed if the velocity shear is greater than twice of the fast-mode speed. Phase-steepened nonlinear Alfven waves with mixed magnetic polarity can be found on both sides of the velocity-shear layer. Wave normal of these nonlinear Alfven waves is nearly anti-sunward in the slow solar wind region but sunward in the fast solar wind region. Our hybrid simulation study shows that RDs with mixed magnetic polarity can be developed from this type of nonlinear Alfven waves. Thus, we propose that RDs can be generated by velocity-shear instability in the solar wind. Comparison between our simulation results and previous solar-wind observations of RDs (Neugebauer, 1989) and nonlinear Alfven waves (Mavromichalaki et al., 1988) will be discussed.
DE: 7811 Discontinuities
DE: 7843 Numerical simulation studies
DE: 2109 Discontinuities
DE: 2134 Interplanetary magnetic fields
DE: 2149 MHD waves and turbulence
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting