Cosgrove Russell B
Center for Geospace Studies, SRI International, Menlo Park, CA, USA.
Sci Rep. 2024 Apr 2;14(1):7701. doi: 10.1038/s41598-024-58512-x.
The ionospheric conductance is the major quantity that determines the interaction of the magnetosphere with the ionosphere, where the magnetosphere is the large region of space affected by Earth's geomagnetic field, and the ionosphere is its electrically conducting inner boundary, lying right on the edge of the atmosphere. Storms and substorms in space dissipate their energy through ionospheric currents, which heat the atmosphere and disrupt satellite orbits. The ionospheric conductance has, heretofore, been estimated using the staticized physics known as electrostatic theory, which finds that it can be computed by integrating the zero-frequency conductivity along the lines of Earth's geomagnetic field. In this work we test this supposition by deriving an electromagnetic solution for collisional plasma, and applying it to obtain a first-ever fully-electromagnetic calculation of ionospheric conductance. We compare the results to the field line integrated conductivity, and find significant differences on all scales investigated. We find short-wavelength, mode-mixing, and wave-admittance effects that were completely unexpected. When this theoretical result is matched with recent observational findings for the scale of the magnetosphere-ionosphere coupling-interaction, there results a situation where small- to intermediate-scale effects really may contribute to global modeling of the Sun-Earth system.
电离层电导率是决定磁层与电离层相互作用的主要因素，其中磁层是受地球地磁场影响的广大空间区域，而电离层是其导电的内边界，恰好位于大气层边缘。空间中的风暴和亚暴通过电离层电流耗散能量，这会加热大气层并扰乱卫星轨道。迄今为止，电离层电导率一直是使用称为静电理论的静态物理学来估算的，该理论发现它可以通过沿着地球地磁场线积分零频率电导率来计算。在这项工作中，我们通过推导碰撞等离子体的电磁解并将其应用于首次获得电离层电导率的全电磁计算来检验这一假设。我们将结果与场线积分电导率进行比较，发现在所有研究尺度上都存在显著差异。我们发现了完全出乎意料的短波、模式混合和波导纳效应。当这一理论结果与最近关于磁层 - 电离层耦合相互作用尺度的观测结果相匹配时，就会出现一种情况，即小到中等尺度的效应可能真的有助于太阳 - 地球系统的全球建模。
