摘要
基于考虑电离层离子的电磁波传播方程,对ELF(Extremely Low Frequency,3~30 Hz)/SLF(Super Low Frequency,30~300 Hz)/ULF(Ultra Low Frequency,300~3000 Hz)/VLF(Very Low Frequency,3 kHz~30 kHz)频段的电磁波从大气层向电离层传播的过程进行了数值模拟,重点研究了电离层离子对该传播过程的影响.数值模拟结果表明,离子对ULF/VLF频段电磁波从大气层到电离层的传播影响较小,可忽略不计,而对ELF/SLF频段电磁波的传播影响较大.ELF/SLF频段电磁波多被限制在岩石圈-电离层波导中,只有少部分可穿透电离层,且与水平极化(Transverse Electric,TE)波相比,垂直极化(Transverse Magnetic,TM)波更易穿透电离层.无论是TE波还是TM波,其穿透电离层后更容易转变为寻常波,从而在电离层中快速衰减.而电离层离子的存在会同时削弱电磁波的反射和透射作用,阻碍电磁波向电离层传播,并加速非寻常波的幅度衰减.电离层离子密度越大,对电磁波的吸收作用越明显,而离子的快速运动则有助于电磁波穿透电离层.本文数值模拟结果为开展地基人工源发射实验及地震电离层电磁异常圈层耦合机理研究奠定了基础.
Based on the electromagnetic equation considering the ionosphere ions,the modeling of the propagation characteristic from the atmosphere into the ionosphere for the ELF(3~30 Hz)/SLF(30~300 Hz)/ULF(300~3000 Hz)/VLF(3 kHz~30 kHz)electromagnetic wave is implemented in this paper,focusing on the influence of the ions on the propagation process.The results show that the ions could be ignored for ULF/VLF electromagnetic waves penetrating from the atmosphere into the ionosphere,but have a great impact on the ELF/SLF waves.The ELF/SLF electromagnetic waves are mostly restricted to lithosphere-ionosphere waveguide.It's easier for the TM(Traverse Magnetic)wave to penetrate into the ionosphere than the TE(Traverse Electric)wave.The electromagnetic wave is more likely to be transformed into the ordinary wave after penetrating the sharp boundary,which will decay rapidly in the ionosphere.The presence of ionosphere ions will weaken the reflection and transmission of the electromagnetic wave at the same time,hindering the penetration into the ionosphere,and may accelerate the attenuation of the extraordinary wave.The greater the density of ions in the ionosphere are,the severer the absorption of electromagnetic waves is,while the rapid movement of ions helps the electromagnetic wave penetrating the ionosphere.The work provides a fundamental basis for the ground-based artificial experiment and the further study of seismo-ionosphere coupling mechanism.
作者
王亚璐
张学民
泽仁志玛
王晓
WANG Ya-lu;ZHANG Xue-min;ZEREN Zhi-ma;WANG Xiao(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;Space Observation Research Center,National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;China Earthquake Networks Center,Beijing 100045,China)
出处
《地震》
CSCD
北大核心
2022年第4期111-126,共16页
Earthquake
基金
中国地震局地震预测研究所基本科研业务费项目(2019IEF0503)
国家重点研发计划项目(2018YFC1503506)
中国地震科学实验场项目(2018CSES0203)
关键词
电离层离子
ELF/SLF电磁波
低电离层锐边界
反射系数
透射系数
复折射系数
Ionosphere ion
ELF/SLF electromagnetic wave
Sharp boundary of the low ionosphere
Reflection coefficient
Transmission coefficient
Refractive index
