共查询到17条相似文献，搜索用时 218 毫秒
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本文试图建立一个产生低纬Pi2 脉动的亚暴三维电流体系模型.用这个模型可以模拟地球表面不同纬度和经度上记录的Pi2脉动的波形和偏振图,与低纬Pi2脉动的多台观测结果基本相符.从而定量地解释了Pi2脉动和亚暴电流体系的关系. 相似文献
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地震期间的地磁脉动效应 总被引：2，自引：1，他引：1
１９９６年１１月１７日至１１月２９日在新疆喀仁地区８次地震期间观测到的震前发生的高频地磁脉动现象,文中对每次地震前的Ｐｃｌ－２脉动的形态,以及脉动的起动时刻,持续时间,Ｈ分量和Ｄ分量的平均振幅随北京地方时的分布进行了详细研究分析,对这种震前观测到的高频地磁脉动的激发机制也做了深入的讨论,事实表明,这种震前发生的高频地磁脉动的地震的短期预报上可能有广泛的应用前景。 相似文献
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对北京十三陵地磁台站2005年全年的地磁数据进行了统计分析,总结了该地区Pc6脉动的周期分布和发生率等特征.对Pc6脉动与TID的关系也做了一些尝试性探讨.我们选择北京大学多普勒雷达观测到TID事件同十三陵台站观测到Pc6脉动进行比较研究,在2004年12月23日至2006年3月11日这段时间内,共有42个事件满足要求.经过分析发现TID事件与Pc 6脉动在波动频率和波形上有比较好的相关性,讨论了Pc6脉动与TID可能的诱发源. 相似文献
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低纬Pc3脉动空间传播特性的研究 总被引：2，自引：1，他引：1
本文分析了从地球弓激波前的低纬磁流体波到低纬地面台站观测到Ｐｃ３脉动的整个传播过程,总结了国内外对低纬Ｐｃ３脉动传播特性在观测和理论上的主要研究成果,并对今后研究提出一些看法。 相似文献
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工程场地条件评定中的地脉动研究 总被引：13，自引：2，他引：13
为了研究开发更经济，更简便的场地动务特性探测方法，本文简要地回顾了工程场地条件评定中地脉动研究的演进，概述了地脉动观测技术的发展，循着地脉动分析方法的演进历程，叙述了谱和谱比分析方法，利用地脉动频散曲线反演场地速度构造的研究，讨论了各种分析方法的依据和适用条件，指出了目前存在的问题，并探讨了可能的改进途径。 相似文献
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The characteristics of substorm-associated Pi2 pulsations observed by the SABRE coherent radar system during three separate case studies are presented. The SABRE field of view is well positioned to observe the differences between the auroral zone pulsation signature and that observed at mid-latitudes. During the first case study the SABRE field of view is initially in the eastward electrojet, equatorward and to the west of the substorm-enhanced electrojet current. As the interval progresses, the western, upward field-aligned current of the substorm current wedge moves westward across the longitudes of the radar field of view. The westward motion of the wedge is apparent in the spatial and temporal signatures of the associated Pi2 pulsation spectra and polarisation sense. During the second case study, the complex field-aligned and ionospheric currents associated with the pulsation generation region move equatorward into the SABRE field of view and then poleward out of it again after the third pulsation in the series. The spectral content of the four pulsations during the interval indicate different auroral zone and mid-latitude signatures. The final case study is from a period of low magnetic activity when SABRE observes a Pi2 pulsation signature from regions equatorward of the enhanced substorm currents. There is an apparent mode change between the signature observed by SABRE in the ionosphere and that on the ground by magnetometers at latitudes slightly equatorward of the radar field of view. The observations are discussed in terms of published theories of the generation mechanisms for this type of pulsation. Different signatures are observed by SABRE depending on the level of magnetic activity and the position of the SABRE field of view relative to the pulsation generation region. A twin source model for Pi2 pulsation generation provides the clearest explanation of the signatures observed. 相似文献
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IntroductionThere are many kinds of fluctuations in magnetosphere plasma, frequencies concerned are ofa broad range (10--3~106 Hi). Except for electro-magnetic waves (whistled, hydromagnetic wave Alven wave), there is static electric wave mode (plasma wave -- election acoustic wave, ionacoustic wave). Among them, a main fluctuation of hydromagnetic wave phenomena is geomagnetic pulsation. Dungey (1954) believed at first in 1954 that this kind of pulsations can be attributed to hydromagnetic w… 相似文献
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本文分析了1988年12月和1989年1月在长春、北京、兰州3个台站上观测的地磁脉动资料,研究了3个台站同时记录到的Pi2地磁脉动的频谱特征和偏振特性,进而对低纬Pi2地磁脉动的产生和传播机制做了理论研究. 相似文献
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V. I. Degtyarev I. P. Kharchenko A. S. Potapov B. Tsegmed S. E. Chudnenko 《Geomagnetism and Aeronomy》2010,50(7):885-893
The dynamics of the Pc5 and Pi1 pulsation characteristics and relativistic electron fluxes at geostationary orbit were comparatively
analyzed for three nine-day intervals, including quiet periods and periods of geomagnetic storms. It was shown that relativistic
electron fluxes increase considerably when the power of global Pc5 pulsations and the index of midlatitude irregular Pi1 pulsations
increase simultaneously. The correlation between the characteristics of Pi1 and Pc5 geomagnetic pulsations and the level of
the relativistic electron flux at geostationary orbit during the magnetic storm recovery phase were studied. It was shown
that the correlation coefficient of the relativistic electron maximal fluxes during the magnetic storm recovery phase with
the parameter of midlatitude Pi1 pulsations is slightly higher than such a correlation coefficient with the solar wind velocity. 相似文献
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本文利用低纬地磁台站的Pi1、Pi2地磁脉动（Pi1-2）资料和地球同步轨道的Pc5地磁脉动资料,对2004年1月到2006年12月38个磁暴事件的地磁脉动参数进行了统计分析.在此基础上,考虑相对论电子的局部加速机制,并加入损失机制,建立了一个初步的磁暴期间地球同步轨道相对论电子通量对数值的预报模型.利用该模型,我们对上述38个磁暴事件进行预报试验,最优化结果是：相对论电子通量对数值的预测值和观测值之间的线性相关系数为0.82,预报效率为0.67.这说明该模式具有较好的预报效果,也表明利用地磁脉动参数进行相对论电子通量预报是可行的. 相似文献
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P. R. Sutcliffe 《Annales Geophysicae》1997,15(10):1257-1264
The pattern recognition capabilities of artificial neural networks (ANNs) have for the first time been used to identify Pi2 pulsations in magnetometer data, which in turn serve as indicators of substorm onsets and intensifications. The pulsation spectrum was used as input to the ANN and the network was trained to give an output of +1 for Pi2 signatures and –1 for non-Pi2 signatures. In order to evaluate the degree of success of the neural-network procedure for identifying Pi2 pulsations, the ANN was used to scan a number of data sets and the results compared with visual identification of Pi2 signatures. The ANN performed extremely well with a success rate of approximately 90% for Pi2 identification and a timing accuracy generally within 1 min compared to visual identification. A number of potential applications of the neural-network Pi2 scanning procedure are discussed. 相似文献