Electric currents in the ocean induced by the geomagnetic Sq field and their effects on the estimation of mantle conductivity
Electric currents in the ocean induced by the geomagnetic Sq field and their effects on the estimation of mantle conductivity
复制标题
地磁Sq场引起的海洋电流及其对地幔电导率估算的影响
DOI：
10.1111/j.1365-246x.1991.tb02518.x
复制
发表时间：
1991
影响因子：
2.8
通讯作者：
M. Takeda
中科院分区：
文献类型：
--
作者：
M. Takeda
总结
本文模拟了一个由有限电导率的均匀地心球和一个代表海陆分布的非均匀导电薄壳球组成的系统中地磁场Sq在海洋中感应的电流。模拟结果表明，在UT 22小时，感应流在北方太平洋有最大强度，使总感应场增强约60%，即使外部流涡位于欧亚大陆上方，由于海洋的存在，内部流涡也增强约10%。接下来，我们检查了海洋中的电流对地幔电导率估计的影响，发现忽略壳层中感应的电流会导致对地幔导体的传导性和浅度的估计。此外，一个明显的依赖于深度的电导率出现，因为在壳感应电流的影响，即使地幔是一个均匀的导体。根据对P12型1天周期变化场的资料分析，如果忽略壳层电流的影响，则电导率和深度分别为0.1Sm ~（-1）和500 km，如果考虑壳层电流的影响，则电导率和深度应为1 Sm ~（-1）和780 km。
SUMMARY
Electric currents induced in the ocean by the geomagnetic Sq field are simulated for a system which consists of a uniform geocentric sphere of finite conductivity and a non-uniformly conductive thin-shell sphere representing the sea-land distribution. the simulation results show that the induced currents have maximum intensity in the northern Pacific Ocean at 22 hr UT and enhance the total induced fields by about 60 per cent. Even when the external current vortex is located above the Eurasian continent, the internal current vortex is enhanced by about 10 per cent by the existence of the ocean. Next we have checked the effects of the electric currents in the ocean on the estimation of the mantle conductivity and found that ignoring the currents induced in the shell gives a less conductive and shallower estimation of the mantle conductor. Furthermore, an apparent dependence of the conductivity on the depth appears because of the effects of the currents induced in the shell even if the mantle is a uniform conductor. the conductivity and depth are estimated to be 0.1 Sm-1 and 500km respectively from the data analysis for the 1 day period variation field of the P12 mode if the effects of the currents in the shell are ignored, but it should be 1S m-1 and 780 km if the effects are considered.
地磁日变化分析推断地幔电导率的区域性
DOI：
--
发表时间：
2022
期刊：
影响因子：
--
作者：
Koyama;T.;S. Fujita;I. Fujii;K. Baba;and H. Shimizu
通讯作者：
and H. Shimizu