磁静日期间中国大陆地区外源弱磁场研究

利用第四代地磁场综合模型CM4, 研究了中国大陆地区1960-2000年磁静日期间地磁外源弱磁场的变化情况, 计算并分析了外源场中的电离层感应场、环形场以及磁层感应场的分布和变化. 结果显示, 北向分量X的磁层感应场强度总体呈先增加后减少的趋势, 共减少了约7.3nT; 东向分量Y的磁层感应场强度呈先减少后增加的趋势, 共增加了约0.8nT; 垂直分量Z的磁层感应场强度呈先增加后减少的趋势, 共增加了约5.5nT. 三个分量的电离层感应场以及环形场变化幅度很小, 其分布在1960-1970和1970-1980年, 1980-1990 和1990-2000年呈现正负互相变换的现象, 认为该现象可能与太阳11年活动周期有关. 最后对弱磁场随时间变化的结果进行了分析说明.

Study on External Weak Magnetic Field During Magnetic Quiet Periods Over Chinese Mainland

The fourth generation comprehensive model of magnetic field CM4 was used to research the variation of external weak field in magnetically quiet periods over Chinese mainland during 1960—2000.The distribution and variation of ionospheric induced field,toroidal field and magnetospheric induced field separated from the external field were also calculated and analyzed.Results show that in terms of lithospheric induced field,component X’s trend of variation was increased firstly,then decreased with time,the amplitude is about 7.3 nT;Component Y’s trend of variation was initially decreased,and increased with time,the amplitude is about 0.8nT;Component Z’s trend of variation was increased and then decreased with time,the amplitude is about 5.5 nT.The variation amplitude of toroidal field and magnetospheric induced field of three components are relative small.Their distribution during 1960-1970 and 1970-1980,1980-1990 and 1990-2000 show an interesting phenomenon that areas of positive and negative values exchanged each other,which may has something related with solar 11 years’ activities.Finally,analysis and explaination of these results were given.