Magnetospheric processes preceding the onset of an isolated substorm: A Case study of the March 31, 1978, substorm
Magnetospheric processes preceding the onset of an isolated substorm: A Case study of the March 31, 1978, substorm
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孤立亚暴爆发前的磁层过程：1978 年 3 月 31 日亚暴的案例研究
DOI：
10.1029/ja088ia09p07005
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发表时间：
1983
影响因子：
--
通讯作者：
Y. Kamide
中科院分区：
文献类型：
--
作者：
A. Nishida;Y. Kamide
我们利用 IMS 磁力计子午线链和多个航天器提供的数据，详细研究了行星际磁场 (IMF) 南转对磁层状态的影响。 1978 年 3 月 31 日发生了一次明显的亚暴，当时磁力计站位于午夜至早晨区域，航天器位于夜侧磁层的赤道面附近。亚暴扩展阶段的开始时间可以根据地基磁信号和极光信号明确确定，并且在 IMF 向南转向和该开始之间有持续约 1 小时的间隔。在此间隔期间，DP 2 类型的电离层电流系统发展起来。电离层电流的增强是由太阳风-磁层耦合直接驱动的。膨胀阶段的开始与尾部磁场能量密度的降低相关，这提供了亚暴能量是由尾部释放（卸载）能量提供的证据。在整个相对孤立和简单的事件中，极光电离层中消散的亚暴能量很可能是由“直接驱动”和“加载-卸载”两个组成部分提供的，其相对重要性根据不同的亚暴阶段而变化。
We examined in detail the effect of a southward turning of the interplanetary magnetic field (IMF) on the state of the magnetosphere, taking advantage of the availability of the data from IMS magnetometer meridian chains and from several spacecraft. A clear onset substorm occurred on March 31, 1978, when the magnetometer stations were located in the midnight to morning sector and the spacecraft were near the equatorial plane of the nightside magnetosphere. The onset time of the substorm expansion phase could be determined unambiguously in terms of both ground-based magnetic and auroral signatures, and there was an interval lasting about 1 hour between the IMF southward turning and this onset. In this intervening interval the ionospheric current system of the DP 2 type developed. This enhancement of the ionospheric current was driven directly by the solar wind-magnetosphere coupling. The onset of the expansion phase was then associated with the decrease in the magnetic field energy density in the tail, providing evidence that the substorm energy was supplied by the release (unloading) of energy from the tail. It is most likely that substorm energy dissipated in the auroral ionosphere throughout this relatively isolated and simple event was supplied by two components, ‘directly driven’ and ‘loading-unloading’, the relative importance of which varied depending on the different substorm phases.