Objective Lagrangian Vortex Detection in the Solar Photosphere
Objective Lagrangian Vortex Detection in the Solar Photosphere
复制标题
太阳光球层中的客观拉格朗日涡旋探测
作者：
S. Silva;E. Rempel;Tiago F. P. Gomes;I. S. Requerey;A. Chian
太阳光球层中的涡旋可以与许多事件联系在一起，例如小规模的太阳爆发、波激发和太阳大气层上部的加热。尽管它们在太阳物理学中的重要性，但目前对光球涡旋的大多数研究都是基于在参考系的随时间变化的平移和旋转下不是不变的方法，并且是欧拉方法;即，它们基于速度场的单个快照，因此，不传递关于流体粒子在时变场中的真实长期运动的信息。涡流检测方法的另一个问题是，通常它们在高度可压缩流中提供错误的识别。这封信提出了一种新的标准，有效地消除了错误的检测的基础上的流体元素的位移矢量的流线的几何形状，可以很容易地应用到其他天体物理流。新的标准适用于拉格朗日平均涡度偏差（LAVD），这是最近发展起来的框架不变的涡检测方法。LAVD的优点是它通过跟踪流体元素在空间和时间上的轨迹来精确地界定旋涡的外边界。所提出的方法进行了比较，与其他两种技术，使用水平速度场提取的Hinode卫星数据。
Vortices in the solar photosphere can be linked to a wide range of events, such as small-scale solar eruptions, wave excitation, and heating of the upper part of the solar atmosphere. Despite their importance in solar physics, most of the current studies on photospheric vortices are based on methods that are not invariant under time-dependent translations and rotations of the reference frame and are Eulerian; i.e., they are based on single snapshots of a velocity field and, therefore, do not convey information on the true long-term motion of fluid particles on a time-varying field. Another issue with methods for vortex detection is that typically they provide false identifications in highly compressible flows. This Letter presents a novel criterion that effectively removes wrong detections based on the geometry of the streamlines of the displacement vector of fluid elements and can be readily applied to other astrophysical flows. The new criterion is applied to the Lagrangian-averaged vorticity deviation (LAVD), which is a recently developed frame invariant vortex detection method. The advantage of LAVD is that it delimits the vortices’ outer boundaries precisely by following up the trajectories of fluid elements in space and time. The proposed method is compared with two other techniques using horizontal velocity fields extracted from Hinode satellite data.
影响因子：
6.5
作者：
Attie, R.;Innes, D. E.;Potts, H. E.
通讯作者：
Potts, H. E.