Mirror mode waves with anticorrelated density and magnetic field are widely observed in the heliosphere. This paper presents the first evidence of mirror mode waves occurring in the vicinity of a magnetic reconnection site (X-line) at the interface between the solar wind and Earth’s magnetosphere based on the analyses of two Magnetospheric Multiscale (MMS) crossing events along with the Grad–Shafranov (GS) reconstruction model with temperature anisotropy. The GS scheme solves the steady two-dimensional MHD equations in the frame of references moving with the plasma by using the spacecraft measurements. Both events have mirror type of pressure anisotropy and correspond, respectively, to the symmetric and asymmetric Harris type current sheets with the total thermal and magnetic field pressures being approximately constant. The GS reconstruction results show the magnetic reconnection with X line geometry associated with the mirror mode structures on the spatial lengths of 170∼370 km or 1.3∼3 ion gyroradius. The coexistence of mirror waves and magnetic reconnection provides the first observational evidence for the prior theoretical prediction of mixed tearing and mirror instabilities in plasma current sheets with temperature anisotropy.

具有反相关密度和磁场的镜像模式波在日光层中被广泛观察到。本文基于对两个磁层多尺度 (MMS) 交叉事件的分析以及在太阳风和地球磁层之间的界面处的磁重联位点 (X 线) 附近出现镜像模式波的第一个证据。具有温度各向异性的 Grad-Shafranov (GS) 重建模型。GS 方案通过使用航天器测量在随等离子体运动的参考系中求解稳态二维 MHD 方程。这两个事件都具有压力各向异性的镜像类型，并且分别对应于对称和非对称哈里斯型电流片，总热和磁场压力近似恒定。GS 重建结果显示磁重联与 X 线几何形状与 170∼370 km 或 1.3∼3 离子回旋半径的空间长度上的镜模结构相关。镜像波和磁重联的共存为具有温度各向异性的等离子体电流片中混合撕裂和镜像不稳定性的先前理论预测提供了第一个观测证据。