中国大陆地区地磁场Z分量日变化相位的空间分布特征研究

利用全国52个地磁台站近20年的观测数据，分析我国大陆地磁Z分量日变化相位变化的空间分布特征，得到如下结论：（1）所有台站Z分量低点时间均服从正态分布；（2）Z分量低点时间期望值与经度之间具有很强的负相关关系，反映出显著的地方时依赖性；（3）低点时间标准差与纬度之间具有一定的正相关关系；（4）中国大陆存在两个Z分量低点时间的异常区域，均表现为低点时间比周围地区明显提前，且低点时间的离散度大于周边地区；（5）去除异常区观测点数据之后，低点时间标准差呈现出在30°N（和地磁纬度20°）附近为极小值而向低纬和高纬分别增大的特点，用二次或三次曲线可以在一定程度上描述这种相关关系.

Spatial distribution characteristics of geomagnetic Z component phase variation in Chinese mainland

In order to study the spatial distribution of phase variation of geomagnetic Z component, we analyzed the geomagnetic Z component data from 52 Chinese stations from 1986 to 2007. We found that：(1) low point time of the Z component daily variation obeys the normal distribution; (2) expected values of low point time distinctly depend on the local time; (3) there was a moderate correlation between standard deviation and geographic (or geomagnetic) latitude; (4) there were two regions of low point time abnormity in Chinese mainland，both of them have low expected values and high standard deviations. (5) When the data of abnormal regions are deleted, there is minimum standard deviation at 30°N (or 20° of geomagnetic latitude), and higher values at both lower and higher latitude. The relation between standard deviation and latitude can be fitted by quadratic or cubic to some extent.