A new reconstruction method incorporated with pressure anisotropy parameter, , has recently been developed for magnetohydrostatic equilibria and successfully applied to recovering a two‐dimensional (2‐D) magnetic field map of mirror structures observed in the Earth's magnetosheath. Here, is assumed to be a function of magnetic field strength, , alone. The fundamental reconstruction theory assumes that the magnetic field and plasma configurations are time‐independent and 2‐D, which may not be fulfilled in the real applications to satellite observations. When the 2‐D structure is time‐dependent, the intrinsic field‐line invariant is violated so that the quantity is not constant for the same field line. This paper aims to examine the performance of the reconstruction of a time‐dependent mirror structure, using data from a 2‐D, double‐polytropic Magnetohydrodynamics (MHD) simulation. With a single‐branched fitting function for the field‐line invariant, results show that the geometry of time‐dependent mirror structure can be reasonably reconstructed, including the distribution maps of gyrotropic pressures and . As expected, the assumption of is well satisfied for the mirror structure. Additionally, another two reconstruction methods are also tested, namely, the Grad‐Shafranov reconstruction and the reconstruction. The former is considered isotropic pressure, while the latter assumes that is function of vector potential alone. As expected, these two reconstruction methods fail to recover the geometry of the mirror structure. We suggest that use of a single‐branched fitting function is more appropriate for reconstruction of a time‐dependent, wave‐like structure, regardless of which magnetohydrostatic reconstruction method is applied.

中文翻译：

---

基于双多变MHD模拟的时变镜结构的二维重构

最近，已开发出一种结合压力各向异性参数的新的重建方法来实现静磁静力平衡，并成功地应用于恢复在地球磁石中观察到的镜面结构的二维（2-D）磁场图。在此，假定仅是磁场强度的函数。基本的重建理论假设磁场和等离子体的配置与时间无关且为二维，这在卫星观测的实际应用中可能无法实现。当二维结构是时间相关的时，内在的场线不变性被破坏，因此同一场线的数量不是恒定的。本文旨在考察该产品的性能使用二维双多向磁磁流体动力学（MHD）模拟中的数据重建时间相关的镜像结构。通过对场线不变性的单分支拟合函数，结果表明，可以合理地重建时变镜结构的几何形状，包括回旋压力和的分布图。如预期的那样，对于镜面结构的假设已经很好地满足了。此外，还测试了另外两种重建方法，即Grad-Shafranov重建和重建。前者被认为是各向同性压力，而后者则假定是矢量势的函数单独。不出所料，这两种重建方法无法恢复镜面结构的几何形状。我们建议，无论采用哪种静磁静力重建方法，使用单分支拟合函数更适合于时间相关的波状结构的重建。