Inferring of flux rope orientation with the minimum variance analysis technique
Inferring of flux rope orientation with the minimum variance analysis technique
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DOI：
10.1029/2004ja010594
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发表时间：
2004-11
影响因子：
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通讯作者：
C. Xiao;Z. Pu;Zhiwei Ma;S. Fu;Z. Y. Huang;Q. Zong
中科院分区：
文献类型：
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作者：
C. Xiao;Z. Pu;Zhiwei Ma;S. Fu;Z. Y. Huang;Q. Zong
[1]传统的基于磁场的最小方差分析（BMVA）技术和基于电流的MVA（CMVA）方法的磁绳方向推断的准确性进行了检查。MVA测试中使用了四种不同的磁绳模型。研究发现，MVA特征向量的方向与航天器相对于磁绳轴的路径和所遇到的磁绳结构密切相关。对于无力磁绳，BMVA的M方向最适合轴向取向，而对于非无力磁绳，BMVA可能无法作为取向推断工具。来自通过非无力磁通绳的单个卫星路径的磁场数据通常不足以确定绳的方向。可能出现不确定性，因为N和M特征向量都不接近轴向方向。另一方面，基于多个航天器测量的CMVA可能有助于消除这种不确定性，并显示出很大的有效性，用于研究观测到的磁通绳的结构和几何形状。
[1] The accuracy in flux rope orientation inference from both the traditional magnetic-field-based minimum variance analysis (BMVA) technique and the current-based MVA (CMVA) approach is examined. Four different flux rope models are used in the MVA test. It is found that the directions of eigenvectors of MVA are critically dependent on the spacecraft path relative to the flux rope axis and structure of the flux rope encountered. For force-free flux ropes, the M direction of BMVA best fits the axial orientation, while for non-force-free flux ropes the BMVA may fail as the orientation inference tool. Magnetic field data from a single satellite path through non-force-free flux ropes are often insufficient to determine the rope orientation. Uncertainty may appear, as neither the N nor the M eigenvector is close to the axial direction. On the other hand, the CMVA based on multiple spacecraft measurements may help to eliminate such an uncertainty and shows great effectiveness for study of structures and geometries of the observed flux ropes.