极低频电磁观测数据噪声处理方法研究

“十五”期间,在全国各地震台站共安装了约12套ELF极低频电磁观测仪器,从记录到的观测资料来看,所有台站均不同程度地受到工频50 Hz及其谐波的干扰,同时还有一些不必要的信息存在,因此,对ELF观测数据进行滤波处理显得尤其重要。该文用MATLAB编程软件设计了FIR数字滤波器,运用理论数据和ELF实测数据对滤波器的性能进行了验证,分析了ELF时间序列经过带通滤波和陷波处理后的效果,发现其对台站ELF观测数据的处理有一定的应用价值。     

利用大地电磁站间阻抗估算磁暴引起的大地电场

由磁暴引起的地下感应电场(geomagnetic induction electric field,GIE)会影响电网的安全稳定运行,GIE的大小取决于磁暴时磁场的变化率和周围地下介质的电性结构.本文利用在地表观测的磁场与电场数据,首先求得频率域实际地下三维大地电磁站间阻抗,再结合磁暴时段的磁场数据,计算GIE的频谱,最后通过傅里叶反变换,得到GIE时间序列.本文以日本地区三个长期观测的电磁电台站为例,讨论了站间阻抗的长期稳定性,并选取一次典型的磁暴事件,对本文方法进行了验证.结果表明,合成的GIE与实测数据基本一致,说明利用大地电磁站间阻抗,结合地磁台站数据,可以高精度合成GIE.本文方法有助于定量评价磁暴发生时产生的GIE对电网可能造成的破坏作用.     

"张衡一号"卫星电场数据存储实验

"张衡一号"卫星搭载的空间电场探测仪,可采集全球范围的电场数据,为空间科学研究及实验提供原位观测数据.该载荷产出的波形和功率谱数据都是以H5格式的文件方式存储,但由于电场观测数据量巨大,文件方式储存导致数据应用效率极低.因此,本文提出了一种基于关系性数据库的数据存储方法,可以显著提高数据访问时间.试验结果表明本文存储方法可应用到张衡一号卫星其他载荷数据,为电磁卫星海量观测数据的高效应用提供了有效的技术支撑.     

GM4磁通门磁力仪秒数据转换及断记报警软件的开发与应用

使用Java编程语言,编写GM4磁通门磁力仪秒数据转换分数据和断记监视软件.秒数据转分数据的方法是,取整分前后45个数据进行高斯滤波,计算得到分钟值,生成的分钟值文件符合geomag软件要求的数据格式.断记监视的方法是,监视实时生成的数据文件字节数是否持续增加,监视H分量观测值是否恒值,避免仪器走直线而不能及时发现,如果事件发生,触发报警.     

利用地磁台站数据和站间传递函数估算长周期大地电磁测深的本地阻抗

大地电磁测深的有效信号为天然电磁场,容易受到人文电磁噪声干扰,如何提高大地电磁资料的信噪比,已经成为制约大地电磁应用和发展的一个重要因素.本文利用地磁台站数据,首先将地磁台站数据转化为长周期大地电磁测深所采集的磁场数据格式,利用远参考方法估算长周期大地电磁测点与地磁台站之间的站间传递函数,包括长周期大地电磁测点电场与地磁台站水平磁场之间的拟阻抗,以及长周期大地电磁测点水平磁场与地磁台站水平磁场之间的水平磁场传递函数,将拟阻抗与水平磁场传递函数相乘便可以得到长周期大地电磁测点本地阻抗的无偏估计.实测数据处理结果表明,该方法可以提高本地阻抗估算的数据质量,减小阻抗估算误差.     

红山台ELF电磁场功率谱密度的时间分布特征

利用红山地震台ELF极低频观测数据处理得到不同观测分量、不同频率功率谱数据的时间序列,并通过对数据进行作图分析,得出红山台电磁场功率谱密度的时间分布具有如下特征:(1)电磁场功率谱密度均具有夏强冬弱的季节分布,呈正弦波形态,夏季变化幅度是冬季的1~10倍不等;(2)不同频率上,各测项功率谱密度无多年趋势性变化特征,年际变化幅度小于年内1~3个数量级。     

电离层人工调制在水平分层电离层中所激发的ELF波辐射

通过大功率ELF/VLF调幅高频波能有效地扰动低电离层,形成等效的ELF/VLF电离层虚拟天线,用来辐射ELF/VLF波,所辐射出的低频信号可以进入中性大气层形成地球-电离层波导.本文基于调制加热模型,采用全波有限元算法计算由人工调制电离层所形成的电偶极矩所辐射出的ELF波在水平分层电离层中的波场,计算结果将与地面观测结果进行比较.模拟结果表明,所辐射出的ELF波在电离层中形成一个窄的准直波束,海面所能接收到的ELF信号强度为pT量级,并且频率越低,海面所接收到的场强就越小,与HAARP实验数据一致.结果还表明,低纬电离层对低频信号的传播衰减较大,并且所能透射出电离层的角度小,因此高纬地区更适合地球-电离层波导的激发.     

崇明地震台ELF观测数据受地铁干扰情况分析

简要介绍崇明地震台ELF电磁观测系统,对观测数据在干扰时段与无干扰时段功率谱值进行对比分析,发现城市轨道交通对崇明台ELF观测的磁场数据存在干扰,且对磁场低频段干扰较大;对电场数据未见明显干扰;磁场与干扰源方向存在相关性。     

全国地震前兆台网观测系统整合

我国前兆台网先后经历了模拟和人工、“九五”数字化、“十五”网络化等多个阶段,导致并行运转着模拟和人工、“九五”、“十五”三套观测系统,它们在通信协议、软件系统、数据库系统、数据格式、数据汇集和管理流程等等各个方面均存在着较大的差异.因此,自2010年起,中国地震局决定实施前兆观测系统并网,主要目标是将“九五”仪器通过接入改造为网络化仪器接入到“十五”系统中,通过软件方式将模拟和人工仪器接入到“十五”系统中,实现与“九五”、模拟和人工仪器与“十五”网络化仪器的并网运行,同时对相关的软件系统、数据库系统、数据格式、数据汇集和管理流程等进行升级完善和统一.     

地震前兆仪器实时数据动态与异常报警

利用后台多线程与事件触发技术,实现对地震前兆仪器实时数据的动态展示;通过对实时数据进行长短窗比值与4倍均方差、时均值、日均值等计算,实现实时数据的异常报警功能,并将该功能模块封装成独立控件供用户使用。该控件可实现对全国所有支持实时采集的前兆仪器进行实时数据采集与动态曲线绘制,可实现对各仪器测项实时曲线的浏览观测,具有自动连接、断网重连、网络状态显示、数据异常报警等功能,同时起到仪器监控的目的。     

Establishment of the ELF Network in Yunnan and Electromagnetic Precursory Monitoring Results of the Yangbi MS5.1 Earthquake on March 27, 2017

This paper summarizes the layout of the Yunnan seismic ELF electromagnetic observation network, site selection, ELF electromagnetic instrument system, data processing and other construction. The principle and method of using the ELF electromagnetic wave technique to monitor and predict earthquakes are expounded. The long term monitoring of ELF electromagnetic fields is carried out in the Yunnan earthquake prone area, and at the same time, the changes in electrical parameters and spatial electromagnetic fields of the regional crustal medium structure are monitored. The functions such as automatic, quasi real time, remote monitoring, network monitoring, data processing specialization, data service, data sharing and industrialization of the ELF electromagnetic observation data have been realized. In order to capture the deep electromagnetic precursory information of the earthquakes, service for earthquake prediction research, which has broad application prospects and development potential. Through the research of the seismicity of Yunnan in the trial run period of the project, the preliminary results of the extreme low frequency electromagnetic observation of the Yunnan earthquake in recent years are given. The electromagnetic precursors and the electromagnetic effects of the Yangbi earthquake are recorded. In the 3-month period before the earthquake, the power spectrum of the electric and magnetic fields, the apparent resistivity and the impedance phase in the observed signals are all abnormal, and gradually increased with time. The maximum value is reached 20 days before the earthquake, and an earthquake occurs when the change is restored to normal.     

Global Lightning Activity on the Basis of Inversions of Natural ELF Electromagnetic Data Observed at Multiple Stations around the World

The monitoring of global lightning activity and its spatial and temporal variations is known to be very essential for the study of global warming, the subject of greatest concern to human beings on planet Earth today. As a method of remote sensing for the global lightning distribution, we have proposed an inverse problem by using the data of natural electromagnetic noise in the ELF (extremely low frequency) Schumann resonance (SR) band observed simultaneously at a few stations around the world. The fundamentals of this inversion problem (or ELF tomography) to the SR data have been presented and the first attempt to deduce the global lightning distribution by means of the real SR data has been performed, which has indicated a possibility of snapshots of well-known thunderstorm centers on the globe. This ELF tomography consists of two stages. The first stage is the inversion of the ELF field power spectra to the distribution of lightning intensity by distance relative to an observation point. The obtained distance profiles of intensity of sources at a few stations are used as tomographic projections for reconstructing a spatial distribution of sources in the second stage. Maps of the global lightning distributions constructed by the result of inversions of ELF background field spectra obtained from three stations around the world show that the most active regions vary meridionally on the diurnal time scale being connected mainly with continental areas in the tropics. We do hope that this kind of inversion method to multi-stationed ELF data will be of great importance in the future.     

The Background Variation of Natural Source ELF and Its EM Abnormal Phenomena in Yunnan Earthquakes

In order to add earthquake monitoring methods and develop new method research, the ELF Network for Earthquake Monitoring selected 30 stations in the Capital Circle and the Sichuan-Yunnan region. Finding electromagnetic field background variation is the basis of distinguishing the seismic electromagnetic anomalies. This paper introduces the data acquisition and selection of the Shexian, Anqiu, Lijiang and Dali stations which have recorded for longer time with better data and are located on the similar latitude. Then we use the natural source electromagnetic field''s auto-power spectrum to express the intensity of the electromagnetic field. By using power spectral data of many frequencies in the observation frequency band, after the data pre-processing and sliding average noising, the background variation of extremely low frequency stations and the range ability were acquired. Taking the Baoshan M5.1 earthquake on October 30, 2015 and Dali M5.0 earthquake on May 18, 2016 as examples, the authors analyzed the earthquake electromagnetic anomaly characteristic of ELF stations around the earthquakes.     

地震地磁场野外观测同步控制系统研制与应用

针对地震地磁野外观测的需求,开发研制了一种基于无线网络的野外同步观测系统。该系统主要由接口单元、采集控制(CPU)单元、无线单元、传输网络、计算机控制中心等组成。该系统操作简单,实用性强,具有远程唤醒及休眠、校时等服务功能,也可应用到地磁台阵的数据传输与同步工作中。     

Monitoring Efficiency Evaluation of the Well-water-level Observation Network in China

In order to understand the monitoring efficiency status of the well-water-level observation network in China after the completion of the 10 th "Five-year Plan " digital network project,and to provide a basis for the future network optimization and equipment updating, the monitoring efficiency of the well-water-level observation network was evaluated. On the whole,61. 8% observing stations have good monitoring effectiveness,the observation environment of 73. 5% of observing stations meets the monitoring requirements of well-water-level. The operation status of the network is as a whole getting better,operation rates of 75% observing instruments are above 95%. Most well water levels can monitor crustal stress changes and seismic activities. However,some observation stations,due to inherent deficiency in wells,environmental disturbance,instrument aging,and low-level operation and maintenance,need to improve the monitoring efficiency level by taking measures such as observation environment improvement,equipment updating,and management training. About 6. 5% of the stations need to stop observation due to the unqualified observational environment.     

ATG-6118H型测氢仪校准与性能检测及其结果

氢气具有较强的映震灵敏性,氢气观测是探索地震短临预报的新途径。ATG-6118H痕量氢气在线自动分析仪是一种用于测量地下流体逸出氢气的新型数字化观测仪器,可以现场进行全自动连续测定,具有灵敏度高、自动化程度高、功耗低、操作简单等特点,具有网络远程诊断和数据处理分析功能,可以精确分析空气及井水中逸出的痕量氢背景值。目前我国尚未形成统一的痕量氢分析仪的检测规范,本文根据实际检测要求,对ATG-6118H痕量氢气在线自动分析仪进行了校准实验、检出限实验以及精确度实验,并对8台仪器性能进行了对比。通过指标评价确定了该仪器的性能检测方法的可行性,适合在具备数字化观测条件的全国地震地下流体台站以及具备断层气观测条件的台站推广应用。     

不同型号测氡仪器在宁德一号井观测效能分析

BG2015R测氡仪近年来作为新型仪器开始应用于地震行业氡观测,但以正式观测仪器进行氡浓度观测的地震台站相对较少。宁德地震台2019年1月安装了该仪器,经试运行后,于2020年1月正式入网运行,在观测过程中对该仪器的性能及运行特性有了一定的了解。本文通过在宁德一号观测井开展SD-3A、BG2015R两套测氡仪系统串网同步、对比观测,并对观测数据及仪器运行进行了比较分析,为其他地震台站在仪器选型、数据分析及系统运维方面提供借鉴。      

远程监控系统在地震台站运维中的应用

目前,山西地震台站运维方式基本以现场运维为主,缺乏远程监测及控制手段。该研究依托成熟的物联网产品,并将其引入地震监测台站,通过手机APP和电脑监控程序相结合的方式,实现对地震台站专业仪器的远程监控和远程控制等功能,最大限度降低地震台站的维护成本。从技术上有力推进"有人看护、无人值守、远程维护、多维产出"的地震台站运维工作模式。     

气象三要素观测数据的共享

地震仪器不同程度地受气象因素干扰,为此地震台站往往根据不同的前兆仪器,安装相应的气象观测仪。以GPS观测仪器配套的PTR-Ⅲ气象仪为例,分析该仪器共享"十五"观测网络的WYY-1型气象三要素观测仪数据的方法,编写程序实现了自动下载WYY-1气象仪数据,并转换为PTR-Ⅲ气象仪格式,从而减少台站辅助观测仪器的数量,减轻了仪器维护的负担。