Data Mining Inspired Localized Resistivity in Global MHD Simulations of the Magnetosphere
Data Mining Inspired Localized Resistivity in Global MHD Simulations of the Magnetosphere
复制标题
DOI：
10.1029/2022ja030990
复制
发表时间：
2023-01
期刊：
影响因子：
--
通讯作者：
Harry Arnold;K. Sorathia;G. Stephens;M. Sitnov;G. Viacheslav;Merkin;J. Birn
中科院分区：
文献类型：
--
作者：
Harry Arnold;K. Sorathia;G. Stephens;M. Sitnov;G. Viacheslav;Merkin;J. Birn
通过利用基于地磁指数和太阳风参数的磁层中原位磁力计观测数据挖掘来重建地球磁场和相关电流的最新进展已被证明在再现观测到的离子扩散区域方面非常准确。受到 2017 年 7 月 6 日发生的亚暴数据挖掘结果的启发，我们研究了在磁层全球模拟中将局部电阻率区域放置在特定位置的效果。当包含显式电阻率时，模拟在当天 15:35 UT 离子扩散区域的磁层多尺度任务观测的同一时间和位置形成一条 x 线。如果没有这种明确的电阻率，重新连接会在亚暴后期形成，并且距离地球太近（≳−15RE），这是地球磁层全球模拟的常见问题。由于局部电阻率，重联发生在尾部更远的地方，其结果是重联流出将磁通量向地球传输，从而防止电流片变薄到足以在更靠近地球的地方发生重联。当这些流从内部磁层向后反弹时，它们可以暂时局部（在黎明-黄昏方向）拉伸磁场，从而在近地区域形成小尺度的 x 线。由于这些 x 线 (≲5RE) 的交叉尾部范围窄且寿命短 (≲5 分钟)，因此很难通过原位测量进行观察。未来的工作将使用 5 分钟节奏数据挖掘重建来探索随时间变化的电阻率。
Recent advances in reconstructing Earth's magnetic field and associated currents by utilizing data mining of in situ magnetometer observations in the magnetosphere based on geomagnetic indices and solar wind parameters have proven remarkably accurate at reproducing observed ion diffusion regions. We investigate the effect of placing regions of localized resistivity in global simulations of the magnetosphere at specific locations inspired by the data mining results for the substorm occurring on 6 July 2017. When explicit resistivity is included, the simulation forms an x‐line at the same time and location as the Magnetospheric Multiscale Mission observation of an ion diffusion region at 15:35 UT on that day. Without this explicit resistivity, reconnection forms later in the substorm and far too close to Earth (≳−15RE), a common problem with global simulations of Earth's magnetosphere. A consequence of reconnection taking place farther down the tail due to localized resistivity is that the reconnection outflows transport magnetic flux Earthward and thus prevent the current sheet from thinning enough for reconnection to take place nearer Earth. As these flows rebound tailward from the inner magnetosphere, they can temporarily and locally (in the dawn‐dusk direction) stretch the magnetic field allowing for small scale x‐lines to form in the near Earth region. Due to the narrow cross‐tail extent of these x‐lines (≲5RE) and their short lifespan (≲5 min), they would be difficult to observe with in situ measurements. Future work will explore time‐dependent resistivity using 5 min cadence data mining reconstructions.