顶部电离层ELF/VLF电磁波动产生机理及传播特征研究

顶部电离层是地震电磁监测试验卫星“张衡一号”CSES的轨道空间，这个空间由于圈层耦合作用下产生了各种ELF/VLF频段的电磁波动，但目前对这些波动的产生及传播机制尚未得到清晰的解释，这对从CSES观测提取地震空间电磁前兆信号带来困难。本项目利用我国最新发射的CSES和美国DMSP卫星联合研究顶部电离层不同类型、不同来源的ELF/VLF电磁波动的产生及传播机理；结合从地表到顶部电离层不同高度观测数据，研究强震引起的ELF/VLF电磁辐射在不同高度上的传播特征；利用时域有限差分方法模拟震源区的ELF/VLF电磁辐射从地表到顶部电离层的传播过程。本项目的实施不仅为提取地震空间电磁前兆信息提供重要的依据，而且还有助于更加深入地了解顶部电离层的空间物理过程。

The upper ionosphere is the orbital region of earthquake-monitoring satellite CSES, and it is a complicated perturbation system due to coupling effects of different spheres of geo-space, generating different types of electromagnetic waves at ELF/VLF frequency band. However, the generation and propagation mechanism of these ELF/VLF electromagnetic waves in the upper ionosphere is still not fully understood, bringing difficulties to extract seismic electromagnetic precursor from electromagnetic satellite data. In this project, firstly, we will combine observations from the newly launched China’s first earthquake-monitoring satellite CSES and USA’s DMSP satellite, to systematically study the ELF/VLF electromagnetic waves with different sources and types in the upper ionosphere, to explore the generation and propagation mechanism of waves. Secondly, we will carry out the comparative study between observations from ground to the upper ionosphere, to investigate propagation characteristics of seismic ELF/VLF waves at different altitudes from ground to the upper ionosphere, aimed to improve the method of extracting seismic precursor from space observations. Thirdly, based on the results of observations, we will simulate how ELF/VLF waves which are induced by earthquakes propagate from ground to the upper ionosphere, by using the finite-difference time domain method. The expected results will lay a good foundation for extracting earthquake precursors from satellite observations, and also contribute to a better understanding about the physical process of the upper ionosphere.