基于多台站观测的中国区域地磁指数

New Regional Geomagnetic Activity Index Based on Multi-station Observation

利用中国14个地磁台站和全球23个地磁台站的H分量分钟值数据,分析单台站小时幅度指数r_H的时空分布特征,在此基础上结合台站之间r_H指数的相似度度量(残差指数Ra),采用K均值聚类算法将中国14个地磁台站划分为7个区域,根据加权法计算各区域的区域指数Rr.结果表明,r_H指数具有27天太阳自转周变化,季节变化不显著,但仍存在春秋季大而冬夏季小的特征;在空间变化上,r_H随纬度的增高而增大,并且在磁暴期间r_H指数的幅值和形态均表现出明显的经度差异,随地方时呈现晨-昏不对称现象;与Dst指数、SYM-H指数、Kp指数及各区域内台站的H分量观测数据对比分析发现,区域指数Rr能有效反映区域地磁扰动.

With the data of 14 geomagnetic observatories in China and 23 geomagnetic observatories abroad,both temporal and spatial variation characteristics of r_H index are analyzed.And the 14 geomagnetic observatories in China are divided into 7 regions by using K-means clustering algorithm based on the similarity measurement,and the residual index(Ra) of r_H index between each two observatories.Then the regional r_H index(Rr) of each region is calculated by linear weighted sum method.The results show that r_H has a periodic change in 27 days,which is the solar rotation cycle.Although no significant seasonal variation is found in r_H,it is also shown that the average of r_H in spring and autumn is greater than in summer and winter.For spatial variations,r_H increases with the latitude.There are some obvious difference in amplitude and morphology of r_H during geomagnetic storms,and the feature of dusk-dawn asymmetry is found.Comparison with the observational data of H component and other Global geomagnetic activity indices,such as Dst,SYM-H and Kp,indicate that Rr can reflect the regional geomagnetic disturbance effectively.