Stormtime Energetics: Energy Transport Across the Magnetopause in a Global MHD Simulation
Stormtime Energetics: Energy Transport Across the Magnetopause in a Global MHD Simulation
复制标题
DOI：
10.3389/fspas.2021.756732
复制
发表时间：
2021-10
期刊：
影响因子：
--
通讯作者：
A. Brenner;T. Pulkkinen;Q. Al Shidi;G. Tóth
中科院分区：
文献类型：
--
作者：
A. Brenner;T. Pulkkinen;Q. Al Shidi;G. Tóth
太阳风和磁层之间的耦合可以用通过被称为磁层顶的分离边界的能量转移来表示。地球空间模拟使用空间天气模拟框架（SWMF）的多ICME的影响事件在2014年2月18日至20日，为了研究在风暴条件下通过磁层顶的能量传输。使用修正的等离子体β和完全闭合的磁力线标准，在下游距离为− 20 Re时，识别磁层顶边界。利用Geotail、Themis和Cluster的观测数据以及Shue 1998模型对模拟结果和磁层顶边界位置进行了验证。一旦识别出边界，就根据总能量通量K、坡印廷通量S和流体动力学通量H计算能量传递。考虑了地面运动的影响，探讨了磁层顶表面能量传输在向阳面X > 0，侧面X < 0，尾部截面X = Xmin区域的区域分布。研究发现，边界上的总积分能流在注入和逃逸之间几乎是平衡的，侧面贡献占主导地位的坡印亭通量注入。坡印廷通量主导净能量输入，而流体动力通量主导能量输出。表面波动有助于显着的净能量转移和比较与舒模型揭示了不同程度的圆柱形的不对称性在整个事件的磁层顶侧翼。最后，将现有的能量耦合代理如Akasofu参数和纽韦尔耦合函数与能量传递结果进行了比较。
Coupling between the solar wind and magnetosphere can be expressed in terms of energy transfer through the separating boundary known as the magnetopause. Geospace simulation is performed using the Space Weather Modeling Framework (SWMF) of a multi-ICME impact event on February 18–20, 2014 in order to study the energy transfer through the magnetopause during storm conditions. The magnetopause boundary is identified using a modified plasma β and fully closed field line criteria to a downstream distance of −20R e . Observations from Geotail, Themis, and Cluster are used as well as the Shue 1998 model to verify the simulation field data results and magnetopause boundary location. Once the boundary is identified, energy transfer is calculated in terms of total energy flux K, Poynting flux S, and hydrodynamic flux H. Surface motion effects are considered and the regional distribution of energy transfer on the magnetopause surface is explored in terms of dayside X > 0 , flank X < 0 , and tail cross section X = X m i n regions. It is found that total integrated energy flux over the boundary is nearly balanced between injection and escape, and flank contributions dominate the Poynting flux injection. Poynting flux dominates net energy input, while hydrodynamic flux dominates energy output. Surface fluctuations contribute significantly to net energy transfer and comparison with the Shue model reveals varying levels of cylindrical asymmetry in the magnetopause flank throughout the event. Finally existing energy coupling proxies such as the Akasofu ϵ parameter and Newell coupling function are compared with the energy transfer results.