Observed geomagnetic induction effect on Dst-related magnetic observations under different disturbance intensities of the magnetospheric ring current
Observed geomagnetic induction effect on Dst-related magnetic observations under different disturbance intensities of the magnetospheric ring current
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不同磁层环流扰动强度下地磁感应对Dst相关磁观测的影响
DOI：
10.1186/s40623-015-0189-z
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发表时间：
2015-01
影响因子：
3
通讯作者：
Mengtan Gao
中科院分区：
文献类型：
--
作者：
Dan Xu;Huaran Chen;Mengtan Gao
根据在地球中纬度表面观测到的地磁扰动的球谐展开，进行了内外场分离，其中外分量为磁层环电流引起的磁扰动，内分量为地球内部相应的感应电流引起的磁扰动。目的是评价感应内场对地表磁观测的影响，揭示内部地磁感应在不同强度磁层环电流波动下的响应性能，从而更好地理解扰动风暴时间（Dst）指数的变化。结果表明，在风暴时间内，内部分量与地面观测的比值并不是恒定的。在风暴主期，该比值随风暴演变呈对数增长趋势，直至最小风量最大值；然后，该比率在长恢复阶段缓慢下降。在内部比值的轨迹上叠加了多个小的对数增长，对应于风暴主阶段临时的环电流强化，并放大了这种强化对地表磁观测的影响。随着磁层风暴从（- 200 nT, - 100 nT）到（- 300 nT, - 200 nT）和（- 500 nT, - 300 nT）的强度，叠加历元分析方法中各风暴组平均比值的最大值分别从0.295±0.014增加到0.300±0.016和0.308±0.015。结果表明，地磁感应强度随外加磁场强度的增大超过线性关系，这在物理上是合理的，并且符合法拉第感应定律。由于海洋的高感应和地球上地幔电导率分布的横向非均质性的影响，地磁感应及其对地表地磁扰动的贡献在各观测站之间存在显著差异。在磁层电流系统的研究中应考虑到这一因素。
Based on the spherical harmonic expansion of geomagnetic disturbance observed on the mid-latitude surface of the Earth, external and internal field separation is conducted in which the external component is magnetic disturbance caused by the magnetospheric ring current and the internal component is that raised by the correspondingly induced currents within the Earth. The objectives are to evaluate the influences of the induced internal field on the surface magnetic observations and to reveal the response performance of internal geomagnetic induction under different strengths of magnetospheric ring current fluctuations for better understanding of the disturbance storm time (Dst) index variations. The results show that the ratio of the internal component to surface observation does not remain constant in storm time. During the main phase of the storm, the ratio variation follows the pattern of logarithmic growth with storm evolution up to the top value at the Dst-minimum; then, the ratio slowly decreases in the long recovery phase. Multiple small logarithmic growths are superimposed on the traces of internal ratios, corresponding to temporary ring current intensification during the storm main phase and amplifying the effect of this intensification on surface magnetic observations. With the intensification of magnetospheric storms from the level of (−200 nT, − 100 nT) to (−300 nT, − 200 nT) and (−500 nT, − 300 nT) classified with the Dst-minimum, the top value of the ratio averaged for each storm group in the superposed epoch analysis method increases from the value of 0.295 ± 0.014 to 0.300 ± 0.016 and 0.308 ± 0.015, respectively. It is demonstrated that the geomagnetic induction exceeds the linear relation with the intensification of the external field, which is physically reasonable and coincident with the Faraday’s law of induction. Due to the effects of high induction of the oceans and lateral heterogeneity of electric conductivity distribution in the upper mantle of the Earth, the geomagnetic induction and its contribution to surface geomagnetic disturbance vary significantly among observatories. This factor should be considered in the research of magnetospheric current systems.
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影响因子：
2.8
作者：
N. Olsen
通讯作者：
N. Olsen
影响因子：
--
作者：
M. Liemohn;M. Jazowski
通讯作者：
M. Liemohn;M. Jazowski
影响因子：
2.8
作者：
Temerin, M;Li, XL
通讯作者：
Li, XL
DOI：
--
发表时间：
1963-06
期刊：
--
影响因子：
--
作者：
M. Sugiura
通讯作者：
M. Sugiura
DOI：
10.1002/0471653764.ch4
发表时间：
2004-08
期刊：
--
影响因子：
--
作者：
D. Misra
通讯作者：
D. Misra