The Magnetohydrodynamic Response of the Magnetospheric Cavity to Changes in Solar Wind Pressure
The Magnetohydrodynamic Response of the Magnetospheric Cavity to Changes in Solar Wind Pressure
复制标题
DOI：
10.1029/ja095ia03p02301
复制
发表时间：
1990-03
影响因子：
--
通讯作者：
D. Southwood;M. Kivelson
中科院分区：
文献类型：
--
作者：
D. Southwood;M. Kivelson
本文利用各种简单模型研究了腔体中磁化冷等离子体在外加压力扰动下的磁流体动力学激发。目的是概述地球磁层因太阳风动压或磁层顶其他压力扰动源的变化而可能产生的反应。虽然源是压缩的，均匀的等离子体在一个腔的脉冲响应被发现包含快速和横模振荡。当模型中引入非均匀性时，快速和横向信号耦合，响应中出现场线共振和阻尼全局本征模。场向电流是电离层对压缩扰动的任何响应的必要组成部分，但仅出现在允许系统不均匀性的模型中。场向电流驱动的电离层运动类似于磁层顶上通量转移事件的特征。该模型与最近空间、地基和电离层雷达测量磁层对太阳风变化的响应定性吻合。
The magnetohydrodynamic excitation of a cold magnetized plasma in a cavity by externally imposed pressure perturbations is examined through use of various simple models. The purpose is to outline the possible responses triggered in the terrestrial magnetosphere by the changes in the solar wind dynamic pressure or other sources of pressure perturbation at the magnetopause. Although the source is compressional, the impulse response of a uniform plasma in a cavity is found to contain both fast and transverse mode oscillations. When nonuniformity is introduced in the model, the fast and transverse signals couple and field line resonances and damped global eigenmodes appear in the response. Field aligned currents are a necessary component of any ionospheric response to compressional perturbations but arise only in models that allow for the nonuniformity of the system. The field-aligned currents drive ionospheric motions similar to those predicted as signatures of flux transfer events on the magnetopause. The models qualitatively fit with the recent space, ground-based and ionospheric radar measurements of magnetospheric response to solar wind changes.