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通过最新的全球地磁模型——CALS10K.1b,结合CALS3K.4与IGRF11模型,计算并分析了10000BC~1990AD期间中国大陆及邻近地区非偶极子(ND)磁场Z分量的时空变化。为了深入了解ND场的变化,从场源的角度,对2n(n=2-10)极子ND场及其对应的能量进行了分析。结果显示在研究期间ND场的变化可分为3个阶段。在10000BC-2500BC期间,ND场以正值为主并持续了近7500a,在2500BC-1500AD期间强度转弱为以负值为主并持续至1500AD,自此快速增强为以正值为主。东亚地区ND场异常基本在截断阶数(n)为3时即形成,且该异常区已在大陆地区内形成了封闭的圆形区域,这意味着前3阶的ND场占据了总ND场强度的大部分。ND场在核幔边界(CMB)处衰减较快,在地表处则趋于稳定。
Based on the latest global geomagnetic model CALS10K.1b and CALS3K.4 and IGRF11 models, the spatio-temporal variations of the Z-component of the non-dipole (ND) magnetic field in the Chinese mainland and its adjacent areas from 10000BC to 1990AD were calculated and analyzed. In order to gain a better understanding of the changes of the ND field, the ND field of 2n (n = 2-10) and its corresponding energy are analyzed from the field source. The results show that the ND field changes during the study can be divided into three phases. During the 10000BC-2500BC period, the ND field is dominated by positives and lasted nearly 7500a. During 2500BC-1500AD, the intensity weakened to a negative value and continued to 1500AD, rapidly increasing from positive to positive. The ND anomalies in East Asia basically form when the truncation order (n) is 3, and the anomalous region has formed a closed circular region in the mainland region, which means that the first 3 orders of ND fields occupy the total ND field Most of the intensity. The ND field decays rapidly at the CMB and stabilizes at the surface.