论文标题
从地下水平磁场检测旅行时间各向异性
Detection of Travel Time Anisotropy from Subsurface Horizontal Magnetic Fields
论文作者
论文摘要
得出了一种时间距离测量技术，以分离由地下水平磁场引起的相位旅行时间各向异性，并且一种使用测得的各向异性来估计该场方向的方法。在具有太阳背景结构的均匀，倾斜磁场中传播的声波的模拟用于验证衍生技术。然后，将过程应用于对黑子的数值模拟，为此，已知地下状态为其提供背景，以提供从Heliose震（Helioseissic and Magicle Imager）观察到的几个黑子的研究中获得的结果。在一分钟的时间内检测到明显的各向异性，并且估计地下场的方位角并与表面磁场的方位角进行了比较。在所有情况下，都发现地下方位角与表面的地下方位角很好，并且数值模拟的结果用于解释检测到的旅行时间各向异性中的特征。
A time-distance measurement technique is derived to isolate phase travel time anisotropy caused by subsurface horizontal magnetic fields, and a method which uses the measured anisotropy to estimate the field's orientation is also derived. A simulation of acoustic waves propagating in a uniform, inclined magnetic field with solar background structure is used to verify the derived technique. Then, the procedure is applied to a numerical simulation of a sunspot, for which the subsurface state is known, to provide context for the results obtained from the study of several sunspots observed by the Helioseismic and Magnetic Imager. Significant anisotropies are detected, on the order of one minute, and the subsurface field's azimuth is estimated and compared with the azimuth of the surface magnetic field. In all cases, the subsurface azimuth is found to be well-aligned with that of the surface, and the results from the numerical simulation are used to interpret features in the detected travel time anisotropy.
