Variations of low‐latitude geomagnetic fields and Dst index caused by magnetospheric substorms
Variations of low‐latitude geomagnetic fields and Dst index caused by magnetospheric substorms
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DOI：
10.1029/2003ja010334
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发表时间：
2004-05
影响因子：
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通讯作者：
Chaosong Huang;J. Foster;L. Goncharenko;G. Reeves;J. Chau;K. Yumoto;K. Kitamura
中科院分区：
文献类型：
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作者：
Chaosong Huang;J. Foster;L. Goncharenko;G. Reeves;J. Chau;K. Yumoto;K. Kitamura
[1]我们目前的观测周期性磁层亚暴和相应的电离层扰动。由于周期性的亚暴发生在稳定的行星际磁场中，我们能够确定哪些电离层特征仅由亚暴引起。结果表明，亚暴爆发后低纬电离层电场的扰动是昼向东、夜向西的，中、低纬地区地面磁力仪的北向（H）偏差在每次亚暴爆发后都有增大（正偏差）的趋势，无论磁力仪是位于昼侧还是夜侧。在偶极过程中，夜侧磁强计H偏差与磁层内磁场Bz分量密切相关。Dst指数在每次亚暴爆发后显著增加20-40 nT。我们建议，在磁强计H场和Dst指数的增加，在响应亚暴爆发是有关的领域的偶极化。在这种情况下，近地中性线向地的夜侧磁层在偶极期间被高度压缩，并且内磁层内的磁通量密度大大增强，导致地面磁力计H分量和Dst的增加。
[1] We present observations of periodic magnetospheric substorms and corresponding ionospheric disturbances. Since the periodic substorms occur during a stable interplanetary magnetic field, we are able to identify which ionospheric signatures are caused solely by substorms. We find that the low-latitude ionospheric electric field perturbation after substorm onsets is eastward on the dayside and westward on the nightside and that the ground magnetometer northward (H) deviations at middle and low latitudes show an increase (a positive bay) after each substorm onset, no matter whether the magnetometers are located on the dayside or on the nightside. The nightside magnetometer H deviations are closely correlated with the inner magnetospheric magnetic field Bz component during the dipolarization process. The Dst index shows a significant increase of 20–40 nT after each substorm onset. We propose that the increase in the magnetometer H field and Dst index in response to substorm onsets is related to the field dipolarization. In this scenario the nightside magnetosphere earthward of the near-Earth neutral line is highly compressed during the dipolarization, and the magnetic flux density within the inner magnetosphere is greatly enhanced, resulting in an increase in the ground magnetometer H component and in Dst.