近300年来的地磁场总能量在地球内部的分布及长期变化

 采用Bloxham J. &; Jackson A.模型(BJ)和国际地磁参考场模型(IGRF)从理论上计算并分析了1690年以来地磁场能量在地球内部的分布及长期变化.结果表明,BJ模型和IGRF模型在相同时段内的总能量变化趋势是基本吻合的.近300a来,地核以外和地表以外地磁场总能量变化的总趋势是持续衰减的,但是地表以外的能量衰减速度比地核以外要快约2.5倍.地磁场总能量随谐波阶数n的变化关系中,各年代n=1～8阶的能量变化相对稳定.磁能密度在地球内部的分布是不均匀的.

Distribution of the total energy of geomagnetic field in the Earth's interior and it's secular variation in recent 300 years

Based on the models of J.Bloxham & A.Jackson(BJ) and the International Geomagnetic Reference Field(IGRF),the distribution of geomagnetic field and its secular variation going back to 1690 year are calculated and analyzed theoretically.The results show that the changing tendencies of the total energy of the two models are basically coincident during the same periods in recent 300 years,the total energy of geomagnetic field is kept decreasing both beyond the Earth's core and the surface,however,the energy decreasing speed beyond the ground is 2.5 times quicker than that beyond the core.The geomagnetic field energy changes with degrees n,of which the changing relationship shows that the energy changes with degrees n=1-8 every year are relatively stable.The geomagnetic energy density is not well-distributed in the earth's interior.