改进磁变仪布局的研究

本文讨论了各分量磁变仪磁针之间的相互影响以及地磁场各分量的变化、记录光入射角对记录的影响，并由此认为一套磁变仪的布局应满意三项标准：（１）各分量仪磁针间的相互静磁影响要小，且任一磁针受其它磁针工作的影响要低于该分量仪记录的分辨率；（２）各分量仪的状态函数稳定，即保持定向能力强；（３）可产生较高精度的线性记录磁照图。鉴于目前的磁变仪布局与此三标准有明显差距，故本文提出了一种新的布局方案，可满足此三项     

水平分量磁变仪标度值随记录n变化率的测定及应用

水平分量磁变仪标度值Ｓ随记录ｎ的变化呈稳定的线性关系，但变化率Ｋｎ各地磁台仪器并不相同。用本文方法测定Ｋｎ可以获得满意的结果。Ｋｎ的精确测定可使水平分量磁变仪非线性记录的计算方法进入实用化，可以校正Ｋ尺或电磁转换函计算值使之更精确，从而提高地磁资料质量。     

SMALL项目数字化地磁资料可靠性分析

在对中美合作 SMALL (中国低纬地磁台阵 )项目安装在北京地磁台 (白家疃 )和云南通海地磁台的磁通门磁力仪记录资料与磁变仪模拟记录资料进行了详细的对比分析后 ,得出的结果表明 ,两者的日变形态、日变幅有较好的一致性 ,所选特定事件的变化幅度非常一致 ,说明磁通门磁力仪记录到的变化磁场的资料是真实可靠的。尽管目前磁通门磁力仪的基线值存在温度影响和离散度较大的问题 ,但随温度变化有明显的规律性 ,若能采取改进观测条件和观测方法以及缩短观测时间等措施 ,并对基线值进温度校正 ,磁通门磁力仪完全可以提供长期连续可靠的资料。而其为地震预报 ,空间环境预报 ,为日地物理 ,空间物理和地磁学的研究提供的高精度、高分辨率、连续可靠的数字化变化磁场资料是磁变仪模拟记录无法比拟的。     

A new investigation on drift of base-line value in geomagnetic observation

Ａｎｅｗｉｎｖｅｓｔｉｇａｔｉｏｎｏｎｄｒｉｆｔｏｆｂａｓｅ┐ｌｉｎｅｖａｌｕｅｉｎｇｅｏｍａｇｎｅｔｉｃｏｂｓｅｒｖａｔｉｏｎＤＯＮＧ－ＭＥＩＹＡＮＧ（杨冬梅）ＹＵ－ＦＥＮＧＡＯ（高玉芬）ＹＯＮＧ－ＦＥＮＺＨＡＯ（赵永芬）ＷＥＩ－ＢＥＩＨＵＡＮＧ...     

磁偏角磁变仪的定向实验

对磁偏角磁变仪进行了定向实验,实验表明磁偏角磁变仪精确定向以在实际工作的环境中进行最佳。磁偏角磁变仪磁针保持定向能力强,垂直分量磁变仪等对该仪器的定向影响可以忽略,不必进行定向改正。     

多功能照相记录磁变仪电源

介绍了多功能照相记录磁变仪电源的主要特性、各部分电路的工作原理、制作方法和使用注意事项，为仿制提供了可靠的依据。该电源还适用于倾斜等照相记录的仪器。     

唐山地震与震磁效应的最佳观测

根据作者与Hastie和Stacey提出的三维压磁效应模式计算方法,围绕1976年唐山大地震,计算了七种不同断层模式的压磁效应,比较了在不同磁纬处,走向滑动断层的不同走向、倾角和埋深在地面上所引起的压磁异常场。结果表明,震磁效应的可观测性同地震的破裂机制有着紧密的关系。断层倾角45——60对应着最佳观测条件,其压磁异常峰值可高达12nT;在最差观测条件时压磁异常量几乎无法测出,这时断层位于磁纬0处,或走向为E-W,或埋深为10公里左右。在大多数模式中,垂直分量的异常略大于总强度异常,但在磁赤道附近可高达三倍左右。对唐山大地震的计算表明,压磁异常量约3——4nT,其异常大于1nT区域的线性尺度与断层长度之比仅为1.04——1.10。由于压磁场是地震过程的一种弱效应场,目前使用仪器的观测精度不够和磁测点的震中距过大,可能是未测出该地震明显的磁异常的原因。      

MAPPING OF TECTONICS OF SEDIMENTS BY AIRBORNE MAGNETICS*

The considerable increase of sensitivity of new magnetometers allows the elaboration of magnetometric maps with contour intervals of fractions of one gamma. On these maps, small anomalies appear which had never been visible before. They are caused by susceptibility contrasts within the sediments. The areal distribution of these small undulations of the magnetic field depends on tectonics, therefore their analysis can give useful information about the tectonic pattern of the sediments. This paper discusses the automatic transformation of these small anomalies into tectonic units. The problem is solved by a method called Digital Template Analysis which has already yielded very useful results in gravity interpretation. The application of the method described is restricted to surveys executed by high sensitivity magnetometers. Therefore it is supposed that in most oil exploration problems these magnetometers will replace instruments with lower sensitivity. The improved magnetometer surveys in combination with the interpretation method described represent a most efficient, fast and unexpensive reconnaissance method.     

Polynomial smoothing of quiet-time magnetic variations for an irregularly spaced array of sites

Both magnetospheric and solid Earth geophysicists often employ two-dimensional arrays of recording variometers to reconstruct the spatial distribution of transient magnetic field variations at the Earth's surface. These discrete data are typically interpolated over a dense grid and the results, for example, are contoured. Few studies, however, have explored the efficacy of employing various polynomial forms for interpolating the same data set, nor have they examined how regional polynomial forms relate to magnetic variation sources on a global scale. The present study addresses some of these concerns. We quantify the characteristics of various smoothed models (i.e., low-order polynomial trend surfaces) for the same data set from a subglobal network of magnetic variometers. Using a relatively quiet interval of undisturbed diurnal variation, we characterize the spatial distribution of the three individual magnetic vector components at a single instant of time—or for what we call a ‘time slice’. We then explore how our model functions are affected by the presence or absence of various site data, i.e., what is the ‘information content’ of a particular site in our array and how important is it to constraining the final smooth model function that we derive? Finally, we explore how such local model functions are affected by including data from outside the array by studying the relation between our local polynomial forms and the global source fields from which they derive.     

Application of Hilbert‐like transforms for enhanced processing of full tensor magnetic gradient data

Commonly, geomagnetic prospection is performed via scalar magnetometers that measure values of the total magnetic intensity. Recent developments of superconducting quantum interference devices have led to their integration in full tensor magnetic gradiometry systems consisting of planar‐type first‐order gradiometers and magnetometers fabricated in thin‐film technology. With these systems measuring directly the magnetic gradient tensor and field vector, a significantly higher magnetic and spatial resolution of the magnetic maps is yield than those produced via conventional magnetometers. In order to preserve the high data quality in this work, we develop a workflow containing all the necessary steps for generating the gradient tensor and field vector quantities from the raw measurement data up to their integration into high­resolution, low­noise, and artefactless two‐dimensional maps of the magnetic field vector. The gradient tensor components are processed by superposition of the balanced gradiometer signals and rotation into an Earth‐centred Earth‐fixed coordinate frame. As the magnetometers have sensitivity lower than that of gradiometers and the total magnetic intensity is not directly recorded, we employ Hilbert‐like transforms, e.g., integration of the gradient tensor components or the conversion of the total magnetic intensity derived by calibrated magnetometer readings to obtain these values. This can lead to a better interpretation of the measured magnetic anomalies of the Earth's magnetic field that is possible from scalar total magnetic intensity measurements. Our conclusions are drawn from the application of these algorithms on a survey acquired in South Africa containing full tensor magnetic gradiometry data.     

基于CARISMA地磁台链观测的IPDP事件的统计分析

亚暴期间磁尾等离子体片离子注入内磁层能够激发电磁离子回旋(EMIC)波.对应于这种EMIC波,地面磁力仪可观测到周期逐渐减小的地磁脉动(IPDP).利用GOES卫星数据,地磁指数和加拿大CARISMA地磁台站的数据,我们研究了IPDP事件的产生与亚暴磁尾注入的关系.同时利用CARISMA地磁台链中的MCMU和MSTK两个台站,从2005年4月到2014年5月期间的观测数据,统计分析了亚暴期间的IPDP事件,研究了IPDP事件的出现率关于季节和磁地方时的分布特征.我们总共获得128个两个台站同时观测的IPDP事件.该类事件关于季节分布的发生率,冬季最小,为13.28%,春季最大,为32.81%,结果表明IPDP事件关于季节分布的发生率受到电离层电导率及亚暴发生率的影响.两个台站同时观测到的IPDP事件最大出现率出现在15—18 MLT(磁地方时),结果表明IPDP事件主要由亚暴期间产生的能量离子注入内磁层,西向漂移遇到等离子体层羽状结构(Plume)区的高密度等离子体所激发.     

核旋仪探头高度的探讨

本文根据试验观测结果,探讨了核旋仪探头高度改变对野外流动地磁场总强度观测质量的影响。认为适当提高探头高度,可以有效地消除地表物质不均匀磁性所带来的随机干扰。具体的探头高度可由不同工作区域的试验工作加以确定。     

An intelligent digital magnetic recording system (DIMARS)

The system consists of three magnetic variometers with electrical output signals for theH, D, andZ components, a proton magnetometer for the total field, a data acquisition system, two cassette recorders, an analogue chart recorder, a calendar clock, and a telex. The analogue and digital input data are sampled at 10 sec intervals, averaged over a minute, and recorded on a magnetic tape cassette. The computed hourly and daily mean values and the daily minimum and maximum values are recorded together with the occurrence times on a second cassette, at the operator's request. Rapid run recording of the 10 sec values of each measured component is initiated automatically during magnetic storms.DIMARS incorporates several test functions as ROM test, A/D converter test, recorder test, telexline test and checking the memory content. The test functions can be activated by the equipment keyboard, or via the telex. The telex can also be operated as an output printer.     

Relation of PC index to the geomagnetic storm Dst variation

Relationships between the polar cap magnetic activity index PC and the magnetic storm Dst index have been studied for the magnetic storms with duration more 12 h and peak value Dst<?30 nT and, observed in 1998–2002 and 2004–2005. Along with PC index the geoeffective interplanetary electric field Em was also examined. It has been found that all examined storms, lying in range from ?30 to ?373 nT, started when the PC index and, correspondingly, the Em field firmly exceeded the threshold >2 mV/m. In particular, the “anomalous” magnetic storm on January 21–22, 2005 occurring under conditions of northward IMF B_Z (Du et al., 2008) is usual phenomena fitted well with the threshold restriction owing to the large IMF By component input. The maximal storm depression (the peak value of Dst) is linearly related to the quantities Em and PC, averaged for the time interval from the storm beginning to the storm maximum. The correlation between Dst and PC is more steady and larger than correlation between Dst and Em, the latter being dependent on Em value (effect of “Dst saturation”). The moment of the firm descent of the Em and PC quantities below the threshold level ～2 mV/m is indicative of the depression damping and transition to the recovery phase. The results are consistent with the similar peculiarities revealed for substorms development (Troshichev and Janzhura, 2009) and support the conclusion that the PC index is a reliable proxy characterizing the solar wind energy having been entered into the magnetosphere.     

地磁台站使用的MD－2型磁变仪数据采集记录系统

我们在１９９２年研制完成了ＭＤ－２型磁变仪数据采集记录系统，它在ＭＤ－１型的基础上进一步改进和增强了系统性能。ＭＤ－２型配接俄罗斯的磁变仪，已在南极和北京以及俄罗斯的部分台站投入使用。它的研制应用大大提高了地磁测量数据的质量和处理速度，实现了台站记录设备的更新换代。     

REMARKS ON THE USE OF THE MAGNETIC GRADIOMETER IN OIL EXPLORATION *

The principle of optical pumping allows the design of magnetometers with high sensitivity. When mapping the field of the total magnetic force, it is no longer possible to make full use of the accuracy of the instruments because the accuracy of the reduction of the diurnal variation is limited. By simultaneously recording with two instruments in different altitudes, the vertical gradient can be measured which doe's not depend on the time variation of the magnetic field. Therefore, the gradiometer seems to be a more adequate tool for oil exploration than the magnetometer. It is investigated in this article whether the results of this gradiometer or the measurements of the total magnetic field by the high sensitive magnetometer are more useful in oil exploration. The article comes to the conclusion that for most problems of oil exploration the total magnetic field is a more valuable unit than the vertical gradient measured directly by the gradiometer. The total magnetic field allows a better investigation of the tectonics than the vertical gradient. The apparent advantages of the gradiometer claimed by its supporters are mainly based on inconsistent mathematical concepts.     

三分量地磁仪自动标定器研制

介绍了用以替代CB－3型磁谱仪配电盘的三分量地磁仪自动标定器的研制原则,技术特性及两年来的使用情况,简要介绍了该仪器的电路原理,电路设计的要点,可供台站维修参考。     

氦光泵磁力仪探头设计和环路数字化研究

磁法勘探是一种常用的地球物理勘探方法,其中光泵磁力仪是国内外应用于航空和地面磁法测量最多的磁力仪器.为满足深部矿产资源勘查对高精度磁测设备的需求,本文开展了低噪声、宽量程的高性能数字氦光泵磁力仪关键技术研究,主要包括磁传感器探头优化设计和新型数字化环路设计两方面.首先通过深入分析影响氦光泵磁力仪灵敏度的主要决定因素,对磁传感器关键部件氦灯、氦室进行小型化技术研究,解决高性能氦泵源和原子气室等关键件的制作工艺,提高氦灯效率和氦吸收室的磁共振信号输出强度,制作出高性能、低噪声的小型化氦光泵探头.然后,针对常规模拟跟踪环路的局限性,通过数字化技术研究,采用FPGA、DSP、DDS、环路跟踪算法和信号处理软件等技术构成新型数字环路,弥补现有基于模拟跟踪环路技术的模拟式氦光泵磁力仪的不足,该数字环路降低了氦光泵磁力仪的电路噪声,增强了抗电磁干扰能力,并扩展了磁力仪的量程.本文通过小型探头和数字环路的技术设计,研制出高精度大量程的地面数字氦光泵磁力仪,并用于第三方测试.通过第三方测试证明：实测仪器的静态噪声小于4 pT,磁场测量范围为20000~100000 nT,梯度容限大于10000 nT/m.     

Generation of magnetic field Pc5 pulsations and particle fluxes during the recovery phase of a magnetic storm on October 31, 2003

The spatial structure of intensive Pc5 pulsations of the geomagnetic field and riometer absorption during the recovery phase of a strong magnetic storm that occurred on October 31, 2003, have been considered in detail. The global structure of disturbances has been analyzed based on a global network of magnetometers and riometers supplemented by the data of magnotometers and particle detectors on geostationary satellites GOES and LANL. The local spatial structure was studied by the data of a regional network of Finland vertical riometers and the stations at the IMAGE magnetic network. Quasiperiodic variations in the magnetic field and riometer absorption are generally similar and have a close frequency composition; nevertheless, their local spatial structures are different, as a result of which the concept that riometer absorption pulsations represent a purely modulation process is doubtful. It is assumed that the observed variations are oscillations of two related systems: the magnetospheric MHD waveguide/resonator and systems including cyclotron noise and electrons. Geomagnetic Pc5 oscillations during the recovery phase of a strong magnetic storm supposedly result from the generation of the magnetospheric waveguide on magnetospheric flanks. An analysis of azimuthal propagation phase velocities indicates that these oscillations depend on intramagnetospheric parameters rather than on the solar wind velocity. The magnetospheric waveguide is in a metastable state when solar wind velocities are high, and the quasiperiodic fluctuations of the solar wind pressure stimulate the excitation of the waveguide.