Minimum Point Shift of the Geomagnetic Vertical Component in Diurnal Variation and the Internal-external Equivalent Current System S_q before the 2008 Wenchuan M_S8.0 Earthquake
Minimum Point Shift of the Geomagnetic Vertical Component in Diurnal Variation and the Internal-external Equivalent Current System S_q before the 2008 Wenchuan M_S8.0 Earthquake
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发表时间：
2015
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通讯作者：
Yuan Gui-pin
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作者：
Yuan Gui-pin
利用球谐分析方法建立了一个分离内外等效电流系Sq的模型，并在汶川8.0级地震前的2008年4月24日和5月9日两个最小位移日前后进行了10天的逐日反演。结合地磁风暴指数，分析了日变化中地磁垂直分量的最小点位移与电流系统的关系。结果表明，在地磁垂直分量日变最小点位移日变化的天数上，南北半球内、外等效电流系的涡心强度都有减小的趋势。在垂直分量地磁日变化中，垂直分量地磁的最小点位移日内，涡旋中心发生了较大的移动。
We built an inversion model for separating internal and external equivalent current systemSqby the spherical harmonic analysis method,which was used to inverse daily for Sq10 days around two minimum shift dates of April 24 and May 9,2008 before the Wenchuan 8.0earthquake.Combining with the index of geomagnetic storms(Dst),we analyzed the relationship between minimum point shift of the geomagnetic vertical component in diurnal variation and current system.We found that,on the days of minimum point shift of the geomagnetic vertical component in diurnal variation,the strength on the center of vortex has a tendency to decrease in internal and external equivalent current system for both the north and the south hemisphere,and the size of the internal field decreased bigger.Further,the center of vortex shifted on the days of minimum point shift of vertical component geomagnetic in diurnal variation.