Preprocessing of Vector Magnetograph Data for a Nonlinear Force-Free Magnetic Field Reconstruction
Preprocessing of Vector Magnetograph Data for a Nonlinear Force-Free Magnetic Field Reconstruction
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DOI：
10.1007/s11207-006-2092-z
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发表时间：
2006-12
期刊：
影响因子：
2.8
通讯作者：
T. Wiegelmann;B. Inhester;T. Sakurai
中科院分区：
文献类型：
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作者：
T. Wiegelmann;B. Inhester;T. Sakurai
关于日冕磁场的知识对于理解许多现象很重要，如耀斑和日冕物质抛射。由于低等离子体β在太阳日冕，日冕磁场通常被认为是无力的，我们使用光球矢量磁像仪数据外推到日冕的磁场与非线性无力的优化代码的帮助下。不幸的是，光球磁场的测量包含不一致性和噪声。特别是，电流矢量磁象仪的横向分量（如Bx和By）有其不确定性。此外，光球层中的磁场不一定是无力的，并且通常与磁迹图上方的无力场假设不一致。我们开发了一个预处理程序，以驱动所观察到的非力自由的数据对合适的边界条件的力自由外推。结果，我们得到了一个数据集，这是尽可能接近的测量数据和一致的无力假设。
Knowledge regarding the coronal magnetic field is important for the understanding of many phenomena, like flares and coronal mass ejections. Because of the low plasma beta in the solar corona, the coronal magnetic field is often assumed to be force-free and we use photospheric vector magnetograph data to extrapolate the magnetic field into the corona with the help of a nonlinear force-free optimization code. Unfortunately, the measurements of the photospheric magnetic field contain inconsistencies and noise. In particular, the transversal components (sayBxandBy) of current vector magnetographs have their uncertainties. Furthermore, the magnetic field in the photosphere is not necessarily force free and often not consistent with the assumption of a force-free field above the magnetogram. We develop a preprocessing procedure to drive the observed non–force-free data towards suitable boundary conditions for a force-free extrapolation. As a result, we get a data set which is as close as possible to the measured data and consistent with the force-free assumption.