基于地磁台站的电离层场源研究
Study of Ionospheric Sources Based on Geomagnetic Stations

自90年代以来，随着地磁观测卫星的不断增加，地磁测深方法迎来了快速发展的阶段。地磁测深的激发场源为磁层环电流和电离层日变(Sq)电流。其中，磁层环电流产生的感应磁场变化周期为几天到几个月，能够提供地幔转换带下部到下地幔(500~1600 km)深度的电导率信息；电离层Sq电流产生的感应磁场变化周期主要为4小时到1天，能够提供上地幔到转换带上部(100~500 km)的电性结构。为了研究电离层电流产生的电磁响应，本文根据球谐分析方法，通过已有的分钟采样的地磁台站数据还原电离层Sq电流，然后根据不同的地球模型，通过积分方程法模拟其在地表产生的电磁场。
Since the 1990s, with the continuous increase of geomagnetic observation satellites, the method of geomagnetic sounding has entered a stage of rapid development. The excitation sources for geomagnetic sounding are the magnetic layer ring currents and the ionospheric daily variation (Sq) currents. Among them, the induced magnetic field changes caused by the magnetic layer ring currents have a period of several days to several months, providing information about the conductivity of the lower part to the lower mantle (500~1600 km) in the mantle transition zone. The induced magnetic field changes caused by the ionospheric Sq currents have a period mainly ranging from 4 hours to 1 day, providing information about the electrical structure from the upper mantle to the upper part of the transition zone (100~500 km). In order to study the electromagnetic response generated by ionospheric currents, this paper, based on the spherical harmonic analysis method, reconstructs the ionospheric Sq currents using existing minute-sampled geomagnetic station data. Subsequently, based on different Earth models, it simulates the electromagnetic field generated by these currents on the Earth’s surface using the integral equation method.