A possible generation mechanism of interplanetary rotational discontinuities

NCUIR > College of Earth Sciences > Graduate Institute of Space Science > journal & Dissertation > Item 987654321/27368

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/27368

Title:	A possible generation mechanism of interplanetary rotational discontinuities
Authors:	Lin,CC;Tsai,CL;Chen,HJ;Weng,CJ;Chao,JK;Lee,LC
Contributors:	太空科學研究所
Keywords:	FIELD DIRECTIONAL DISCONTINUITIES;LARGE MAGNETIC SHEAR;ALFVEN WAVES;INTERMEDIATE SHOCKS;SOLAR-WIND;AMPTE/IRM OBSERVATIONS;MAGNETOPAUSE;RECONNECTION;ULYSSES;STABILITY
Date:	2009
Issue Date:	2010-06-29 18:37:06 (UTC+8)
Publisher:	中央大學
Abstract:	In the present paper, we first examine some interplanetary directional discontinuities with very small B-n/B (<0.1) using intraspacecraft timing method. It is found that the velocity and magnetic field fluctuations of these directional discontinuities satisfy the Walen relation. We suggest that these directional discontinuities are rotational discontinuities. In addition, we investigate the stability of interplanetary rotational discontinuities using one-dimensional hybrid simulations and found that rotational discontinuities with all values of B-n/B can stably exist in the solar wind. In one simulation run, we find that the rotational discontinuity (RD) is still stable when the ratio, B-n/B, equals 0.0001. Finally, from one-dimensional hybrid simulation, we further find that the ratio is significantly reduced after interaction with interplanetary fast shocks. There are a few mechanisms for generation of RDs. Among them, two mechanisms are well accepted. One is nonlinear evolution of Alfven waves in the solar wind, and another is magnetic reconnection near the solar surface. For magnetic reconnection, the reconnection rate, V-1n/V-A1(= B-n/B), in the magnetosphere and solar wind, is usually <0.2. Therefore the generated RDs also have v <0.2. On the other hand, the nonlinear evolution of Alfven waves in the solar wind can generate RDs at all values of v, which contradicts to the Cluster results. We suggest that interplanetary RDs with small B-n/B are likely been generated through magnetic reconnection.
Relation:	JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
Appears in Collections:	[Graduate Institute of Space Science] journal & Dissertation

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