首都圈及邻区极低频天然电磁场时空分布特征研究

A Control Source Extremely Low Frequency electromagnetic technology (CSELF) is produced by combining of geophysics with radio physics. The space and time specific pattern of natural electromagnetic field may affect the measurement result of signal from powerful artificial ELF transmitter. It may also effect the application of EM geophysics, monitoring on EM anomaly. The distributed feature of natural EM field is significantly to the position and time, but it has not been systematically studied in ELF band. The continuous observation of natural EM field in ELF band and the vicinity will be carried out at the network composed of many stations. The typical original data measured in the past using MT method will be collected. Then the characterized distribution of ELF natural EM field in special and temporal domains will be studied and the statistic map of noise distribution will be established. In addition, the EM anomalies and the cause producing these anomalies will also be studied. This study will provide basic information and technical support for Seismic monitoring and the construction of the EM observation network and for the EM data processing and analysis in ELF frequency band.

人工源极低频电磁技术（CSELF）是地球物理和无线电物理原理相结合的产物。天然电磁场（即通信领域称谓的大气噪声）的时空分布可影响到人工源极低频电磁信号的发射和接收效果，影响到利用天然电磁场进行资源勘探等固体地球探测、地震电磁异常监测和环境电磁监测、电磁通信等领域的应用效果。天然电磁场的分布与地理位置和季节等有关，但我国尚未系统进行极低频频段的天然电磁场测量。本研究将在首都圈及其邻区开展台网式的极低频及邻近频段的电磁场连续观测，同时也收集我国不同地区已进行的电磁探测的有代表性的可用的原始资料，研究首都圈及邻区的极低频天然电磁场的时空分布特点,建立大气噪声分布图象，研究电磁场异常的分布及其产生的原因。研究结果不仅为极低频电磁地震监测提供了背景资料，又可用于CSELF技术的信号发射、观测和数据处理方法等方面的研究和应用，也可用于无线电通信、环境电磁监测和国家安全等领域。

人工源极低频电磁技术（CSELF）是地球物理和无线电物理原理相结合的产物。天然电磁场（即通信领域称谓的大气噪声）的时空分布可影响到人工源极低频电磁信号的发射和接收效果，也会影响到利用天然电磁场进行资源勘探等固体地球探测、地震电磁异常监测和环境电磁监测、电磁通信等领域的应用效果。天然电磁场的分布与地理位置和季节等有关，但我国尚未系统进行极低频频段的天然电磁场测量。.本研究在首都圈及其邻区开展台网式的极低频及邻近频段的电磁场连续观测，台网由五个流动台站、极低频探地工程地震预测分系统首都圈六个极低频固定台站以及一个 “十五”期间中国地震局的极低频台站组成，对2014年夏季和冬季至少各一个月的数据进行分析研究，结果显示：夏季电磁场谱密度通常约是冬季的1.5倍，且夏季的变化要剧烈一些，推测是由于夏季雷电活动较多的缘故。对比每天不同时段的电磁场谱分布特点，2:00~8:00时间段的电磁场谱变化最稳定，可能由于该时段电磁干扰小的缘故；哪个时段电磁场谱值最大因台站而异，而且与频率以及季节有关，夏季低频、中频白天谱值通常大于黑天谱值，但大多数台站冬季中频黑天的谱值较大。针对多手段台站，对比其它观测手段发现，电磁场谱值与温度、气压、降水量以及钻孔水位变化之间的相关性较差；电磁场谱与磁暴扰动强度指数kp相关性也不强。