The largest moon in the solar system, Ganymede, is the only moon known to possess a strong intrinsic magnetic field and a corresponding magnetosphere. Using the latest version of Space Weather Modeling Framework (SWMF), we study the upstream plasma interactions and dynamics in this sub‐Alfvénic system. Results from the Hall magnetohydrodynamics (MHD) and the coupled MHD with embedded particle‐in‐cell (MHD‐EPIC) models are compared. We find that under steady upstream conditions, magnetopause reconnection occurs in a nonsteady manner, and the energy partition between electrons and ions is different in the two models. Flux ropes of Ganymede's radius in length form on the magnetopause at a rate about 3 min and create spatiotemporal variations in plasma and field properties. Upon reaching proper grid resolutions, the MHD‐EPIC model can resolve both electron and ion kinetics at the magnetopause and show localized nongyrotropic behavior inside the diffusion region. The estimated global reconnection rate from the models is about 80 kV with 60% efficiency, and there is weak evidence of ∼1 min periodicity in the temporal variations due to the dynamic reconnection process.

中文翻译：

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木卫三上游磁层的重新连接驱动动力学：3D全球展厅MHD和MHD-EPIC仿真

太阳系中最大的卫星，即木卫三，是已知唯一具有强内在磁场和相应磁层的卫星。使用最新版本的空间天气建模框架（SWMF），我们研究了该次Alfvénic系统中的上游等离子体相互作用和动力学。比较了霍尔磁流体动力学（MHD）和耦合的MHD与嵌入式粒子内单元（MHD-EPIC）模型的结果。我们发现，在稳定的上游条件下，磁层顶重新连接以不稳定的方式发生，并且两个模型中电子和离子之间的能量分配不同。盖尼迈德的半径长度的助熔剂以约3分钟的速度形成在磁层顶上，并在等离子体和磁场特性中产生时空变化。达到适当的网格分辨率后，MHD-EPIC模型可以解析磁停顶的电子和离子动力学，并在扩散区域内显示局部非回旋行为。这些模型估计的全球重新连接率约为80 kV，效率为60％，并且证据不充分〜 1周分钟的周期中的时间变化，由于动态再连接处理。