Case studies on the dynamics of Pi3 geomagnetic and riometer pulsations during auroral activations
Case studies on the dynamics of Pi3 geomagnetic and riometer pulsations during auroral activations
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极光激活过程中 Pi3 地磁和测力计脉动动力学的案例研究
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
A. Ranta
中科院分区：
文献类型：
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作者：
N. Kleimenova;O. Kozyreva;K. Kauristie;J. Manninen;A. Ranta
抽象的。本文分析了1997年2月9日连续三次极光激活（18：10、19：48和20：00 UT）的序列。光学极光的增亮与纬度上的脉动riometer吸收和Pi 3地磁脉动的局部爆发相搭配。在两种情况下，最强的向西向电喷流和脚点的向上定向场对准电流相关的极光增亮观察在同一地区的脉动和它们的极化变化的最大幅度。在第三种情况下，存在磁场对准的电流特征，但不是如此明显，以至于无法定义其准确位置。在所有情况下，地磁和吸收脉动的频谱是相似的。仅根据地面观测，很难说高能粒子沉淀（riometer吸收）是否受到地磁脉动的调制，或者地磁脉动是否由沉淀粒子强度控制的电离层电流变化引起。然而，两种不同现象的脉动的局部性质及其相互之间的紧密耦合似乎支持后一种选择。关键词。电离层（粒子沉淀）-磁层物理学（极光现象; MHD波和不稳定性）
Abstract. A sequence of three subsequent auroral activations (at 18:10, 19:48 and 20:00 UT) on 9 February 1997 is analysed. The brightenings of optical auroras were collocated with latitudinally localized bursts of pulsating riometer absorption and Pi3 geomagnetic pulsations. In two of the cases, the strongest westward directed electrojet currents and the footpoint of the upward directed field-aligned currents related to the auroral brightening were observed in the same region as the largest amplitude of the pulsations and their polarization changed. In the third case, field-aligned current signatures were present, but not so pronounced that their accurate location could not be defined. In all cases, the spectra of geomagnetic and absorption pulsations were similar. Based on ground-based observations alone, it is difficult to say whether the energetic particle precipitation (riometer absorption) was modulated by the geomagnetic pulsations or whether the geomagnetic pulsations were caused by varying ionospheric currents controlled by the precipitating particle intensity. However, the localized nature of both pulsations of the two different phenomena and their tight coupling with each other seem to support the latter option. Key words. Ionosphere (Particle precipitation) – Magnetospheric physics (auroral phenomena; MHD waves and instabilities)