共查询到20条相似文献，搜索用时 31 毫秒
1.
N. G. Kleimenova O. V. Kozyreva S. Michnowski M. Kubicki 《Geomagnetism and Aeronomy》2008,48(5):622-630
The observations of the variations in the vertical component of the atmospheric electric field (E z ) at Swider midlatitude Poland observatory (geomagnetic latitude 47.8°) under the conditions of fair weather during 14 magnetic storms have been analyzed. The effect of the magnetic storm main phase in the daytime midlatitude variations in E z in the absence of local geomagnetic disturbances has been detected for the first time. Considerable (～100–300 V m?1) decreases in the electric field strength (E z ) at Swider observatory were observed in daytime simultaneously with the substorm onset in the nighttime sector of auroral latitudes (College observatory). The detected effects indicate that an intensification of the interplanetary electric field during the magnetic storm main phase, the development of magnetospheric substorms, and precipitation of energetic electrons into the nighttime auroral ionosphere can result in considerable disturbances in the midlatitude atmospheric electric field. 相似文献
2.
To study the relations of the polar cap (PC) magnetic activity (characterized by the PC index) to magnetic disturbances in the auroral zone (AL index) the behavior of 62 repetitive bay-like magnetic disturbances has been analyzed. It was found that the PC index, derived as a proxy of the geoeffective interplanetary electric field Em, starts to increase, on average, about 30 min ahead of the magnetic disturbance onset. Value of Em and PC～2 mV/m seems to be necessary for development of the repetitive bay-like disturbances with peak AL exceeding 400 nT. Growth phase duration (the time interval between the start of PC increase and AL sudden onset) and intensity of magnetic disturbances in the auroral zone (AL max) highly correlate with the PC growth rate. The growth phase reduces to a few minutes, if the PC index suddenly jumps above ～6–8 mV/m. The sharp development of Birkeland current wedge during expansion phase insignificantly influences the polar cap activity: the corresponding PC index increase does not exceed 10–20% of the PC value. It is concluded that the PC index may be considered as a convenient proxy of the solar wind energy input into the magnetosphere. 相似文献
3.
D. R. Barraclough T. D. G. Clark S. W. H. Cowley F. H. Hibberd R. Hide D. J. Kerridge F. J. Lowes S. R. C. Malin T. Murphy H. Rishbeth S. K. Runcorn H. C. Soffel D. N. Stewart W. F. Stuart K. A. Whaler D. E. Winch 《Surveys in Geophysics》1992,13(1):47-88
A joint Discussion Meeting of the Royal Astronomical Society and the Royal Irish Academy, held on January 11th, 1991, commemorated the establishment of some early magnetic observatories, discussed recent research using global geomagnetic data and described the present status of magnetic observatories in the United Kingdom. The observatory and instruments at the Dublin magnetic observatory; the origins of the Greenwich magnetic observatory, and why it eventually had to be resited; and the history of the Munich magnetic observatory formed the historical part of the proceedings. Current research topics discussed were the geomagnetic secular variation and deep Earth structure and dynamics; fluid flow patterns near the top of the core; the origin of the annual variation of the geomagnetic field; results of an analysis of monthly means from some British observatories; a new theory of the geomagnetic daily variation; and the interactions between ionospheric science and geomagnetism. The present-day observatory scene was described in terms of the information that can be derived from the almost 40 year series of data from Hartland magnetic observatory; of the methods used to process data from the three UK magnetic observatories, which nowadays are operated automatically and remotely; and (a look into the future) of a new project, INTERMAGNET, which aims to make available, in near real time, data from the world-wide network of magnetic observatories. 相似文献
4.
The paper is dedicated to studying the dynamics of the auroral ionosphere at the level of the sporadic Es layer during magnetospheric disturbances. A new approach to this problem, proposed in the paper, uses the geomagnetic PC index, which is calculated using the magnetic data in the polar caps of the northern and southern hemispheres and manifests the geoefficiency of the interplanetary electric field. It is shown that variations in the sporadic electron concentration in the auroral Es layer could be related to changes in the PC index with a high degree of statistical reliability. However, the character of precipitations of sporadic particles into the ionosphere under high (PC > 2 mV/m) and low (PC < 2 mV/m) magnetic activity differs substantially. During strong magnetic disturbances and under intensified electric fields in the interplanetary environment, the intensity of particle precipitation from the magnetosphere into the E region of the high-latitude ionosphere is governed by the values of the PC magnetic index. During weak magnetic disturbances, short-time pulses of an increase in the PC values, caused by the variability in electric field in the magnetosphere, are the main factor in the occurrence of sporadic ionization in the Es layer. 相似文献
5.
众所周知,在许多地震前可以观测到局部磁异常。选择位于中国最北部的国家级绝对地磁观测台内蒙古满洲里地磁台和黑龙江德都地磁台2008年的观测数据,采用差值法、响应比、能量比等分析方法,对2008年6月10日内蒙古阿荣旗M 5.2地震和7月7日黑龙江龙江县M 4.6地震前的局部空间磁场异常进行分析,并应用斜率分析和差分分析对差值法异常信息进行提取,发现在内蒙古阿荣旗M 5.2地震和黑龙江龙江县M 4.6地震前各方法均存在明显的异常,这些异常在一定程度上反映了台站周围小范围的震源区介质电性结构的变化。同时针对异常幅度、持续时间与地震强度间的关系进行了浅析。 相似文献
6.
《地震科学（英文版）》2010,(4)
By calculating the hourly standard deviation of the first-order differences of the horizontal geomagnetic component minute data,a new index Vr to represent the variation rate of the geomagnetic field was introduced.Vr-indices show similar trends in the temporal change at different observatories and have simultaneous peak values at the observatories covering a large span geographically,which reveals that the source of geomagnetic disturbances represented by Vr is in the magnetosphere.Based on the comparison among Vr,Kp and ap,it is found that generally Vr changes linearly with Kp and ap,which means that the rapid changes of magnetic field usually exist together with magnetic disturbances.But there are exceptions.As Vr can be easily produced by individual observatory in quasi real time and is more sensitive to the variation rate of geomagnetic field rather than the field itself,it can be expected to serve for monitoring or predicting the geomagnetic-induced event in a quick and intuitive way. 相似文献
7.
At high latitudes, sporadic geomagnetic disturbances associated with geomagnetic storms introduce significant uncertainty in measurements by borehole inclinometers during the directional drilling of deep wells. Variations in the magnetic declination may lead to significant deviations of the actual coordinates of the borehole from the prescribed trajectory. Using the methods for calculating the profile of the actual borehole, we conducted model estimates of the influence of sporadic disturbances in the magnetic declination observed during the magnetic storm of October 28–31, 2003 on the displacement azimuth and intensity of borehole bending at the given locations at the sites of two high-latitude magnetic observatories. It is shown that, unless filtered based on the data of parallel observatory measurements, the geomagnetic disturbances can lead to unacceptably large errors in the borehole inclinometer measurements and cause a borehole deflection exceeding the admissible values. 相似文献
8.
V. N. Obridko Kh. D. Kanonidi T. A. Mitrofanova B. D. Shelting 《Geomagnetism and Aeronomy》2013,53(2):147-156
An analysis of IZNIRAN magnetic observatory data indicated that geomagnetic storms with sudden and gradual commencements form two independent populations with respect to the disturbance occurrence time and character because the solar sources of these disturbances are different. Storms with sudden and gradual commencements are caused by coronal mass ejections and high-speed solar wind streams from coronal holes, respectively. 相似文献
9.
The distributions of the natural noise electromagnetic field level in the vicinity of the first Schumann resonance have been
studied based on data from Lovozero observatory (the Kola Peninsula). Daily curves of noise level excesses over specified
thresholds at different geomagnetic disturbances have been constructed. It has been indicated that the curves are morphologically
similar on magnetically quiet days but are highly variable from day to day, although the averaged curves are similar in some
characteristics to the unitary variation in the surface quasistatic electric field. The possibilities of applying the known
formula for the probability distribution of the VLF atmospheric radio noise amplitude in order to analytically describe the
noise level probability distribution have been considered. It has been detected that geomagnetic disturbances pronouncedly
affect the distribution parameters, sharply increasing the amount of large-amplitude noise. 相似文献
10.
A new approach to identify the signals of the Earth’s main magnetic field (core field) based on the magnetic observatory data processing is suggested. The algorithms implemented in the approach are based on the Discrete mathematical analysis (DMA). The developed method is used to analyze the data from 49 midand low-latitude observatories of the INTERMAGNET network collected in 2011–2015. The results are compared with the classical method for determining the periods of low magnetic activity of external origin which is adopted by the International Association for Geomagnetism and Aeronomy (IAGA). The advantages of the suggested new approach are demonstrated. Based on the data records for the selected time intervals, the time series of the core field components and their secular variations are obtained for each observatory. These data are compared to the values predicted by the most accurate core field models: SIFM, CHAOS-6, and EMM-2015. The accuracy of the models is estimated using a set of statistical parameters: Pearson’s coefficient of linear correlation, Spearman’s and Kendall’s coefficients of rank correlation, the mean and median values over the data sets, and the mean difference between the data obtained by the suggested method from observatory measurements and the model predictions. 相似文献
11.
本文分析了电离层对2009年、2013年和2016年朝鲜核试验中地下核爆(Underground Nuclear Explosion,UNE)的响应.利用南北半球IGS站的GNSS-TEC观测数据,发现了在3次核试验期间的磁共轭电离层扰动现象.观测结果表明,3次UNE所产生的电离层扰动分别以228m·s-1、173m·s-1和147m·s-1的速度从核试验爆心地区径向传播.本文研究提出,UNE所产生的电离层TEC扰动是岩石圈-大气层-电离层耦合(Lithosphere-Atmosphere-Ionosphere Coupling,LAIC)电场渗透到电离层高度引发电动力学过程的结果.此外,LAIC电场可以沿磁力线映射到共轭半球,从而在共轭地区造成电离层TEC扰动.因此,在核试验地区附近以及其对应的磁共轭地区,UNE所产生的LAIC电场在电离层TEC扰动的形成中起着关键性的作用. 相似文献
12.
In order to provide a basis for short-term decision-making in the forecasting and monitoring of volcanic activity, we developed an entirely automated system of data acquisition and reduction for magnetic data. The system (Mag-Net) is designed to provide monitoring and analysis of magnetic data on Etna volcano at large distances from the central observatory. The Mag-Net system uses data from an array of continuously recording remote stations spread over the volcanic area and linked by mobile phone to the control center at the local observatory. At this location a computer receives the data and performs data sorting and reduction as well as limited evaluation to detect abnormal behavior or breakdown of remote sensors. Communication software, called MagTalk, is also designed to provide data to distant users. With a view to using continuous magnetic observations in advanced analysis techniques for volcano monitoring, the Mag-Net system also delivers two graphical user interface based applications to provide an interpretation capability. The former, called MADAP, speeds up all the data reduction processes in order to evaluate the reliability of magnetic signals. The latter, called VMM, is a procedure for modeling magnetic fields associated with tectonic and volcanic activity to facilitate the identification and interpretation of the sources of a wide spectrum of magnetic signals. 相似文献
13.
IGRF（国际地磁参考场）是有关地球 主磁场与长期变化的模型，IGRF的误差主要来源于：忽略外源场、球谐级数的截断、台站分 布的不均匀、测量、忽略地壳磁异常场等. 分析我国大陆地区IGRF的误差，有利于我国地磁 研究 人员在工作中合理地应用IGRF资料. 如果不计磁异常与环境干扰都比较大的北京台，29个基 准台的IGRF的误差(均方根差)为146.9nT. 相似文献
14.
《Journal of Atmospheric and Solar》1999,61(10):751-763
We present the results of a Schumann resonance monitoring campaign held at Lehta observatory, Karelia, Russia during July–August, 1998. Three electromagnetic (EM) field components were recorded simultaneously: the vertical electric and two orthogonal magnetic fields. This paper demonstrates advantages of the Poynting vector (PV) technique when studying the space–time dynamics of the worldwide thunderstorm activity from a single observatory. Analysis of the diurnal PV patterns revealed a night-time peak in African thunderstorm activity. This maximum occurs around 02:00–03:00 UT and reaches 1/3 of regular afternoon level. The Schumann resonance structure was discovered in the spectra of the wave arrival angles. 相似文献
15.
P.M. Davis F.D. Stacey C.J. Zablocki J.V. Olson 《Physics of the Earth and Planetary Interiors》1979,19(4):331-336
Cancellation of extraterrestrial magnetic disturbances by taking simple differences between total field readings at spaced stations is imperfect. It is shown that improvement is possible when three component observatory data are available from a single station in the general, but not necessarily immediate, vicinity of an array of total field stations used in a tectonomagnetic study. The local effects of a magnetic disturbance field depend upon its orientation, so that local field differences are more effectively generated by certain orientations of the disturbance field. The orientation of the disturbance field which correlates best with a local difference field is determined by a least-squares method, so that the correlated vector signal can be routinely subtracted from the difference field record. Application of the technique to daily averages of records from three synchronised proton magnetometers on Kilauea volcano reveals a 1.5-nT change in the local field at the time of a flank eruption in May, 1973. This effect was obscured by noise in the raw difference field data. 相似文献
16.
Nonlinear and multifractal approaches of the geomagnetic field 总被引：2，自引：0，他引：2
L. Hongre P. Sailhac M. Alexandrescu J. Dubois 《Physics of the Earth and Planetary Interiors》1999,110(3-4):157-190
Recent nonlinear dynamics techniques have been developed to analyse chaotic time series data. We first summarize the procedure which gives an appropriate reconstruction of the unknown dynamics from scalar measurements in a pseudophase space. It permits, firstly, the representation of the trajectories of the dynamical system—they define an attractor when the system is dissipative—by preserving its topological properties. We then present the invariant measures and ergodic quantities such as the multifractal spectrum and Lyapunov exponents which can be estimated on the reconstructed attractor. The multifractal analysis provides us with a characterization of the scaling energy of the process whereas the Lyapunov exponent gives another statistical measure of the stability of the dynamics. The estimation of these quantities was tested on synthetic data. The nonlinear and multifractal analyses were finally applied to the hourly mean values of the magnetic field recorded at the Eskdalemuir (ESK) observatory over 79 years (692,520 data measurements for each component). The estimations of a 5-dimensional pseudo-phase space and a positive Lyapunov exponent confirm the possibility of low-dimensional deterministic chaos in the magnetic field observations at ESK observatory. The correlation between the solar activity (the Wolf number), the unstable nature of the magnetic field, and the singularity spectrum points out the forcing of the solar cycles on the dynamics of the magnetic field at ESK observatory. 相似文献
17.
A type of relatively low frequency ULF magnetic disturbance has been generally observed by the magnetic induction-meter since
it’s operation at Baijiatuan observatory in Beijing. As the amplitudes and frequencies of such disturbance signals change
with time and are different from the disturbances produced by some man-made magnetic sources, therefore they are usually taken
as a kind of earthquake precursors for ULF electro-magnetic emission. However, a comparative analysis with magnetic storms
on the magnetogram obtained by variometerat the same station indicates that such signals always occur in the period of magnetic
storm occurrence and so far we have not found the cases where such signals occur with no magnetic storms, therefore this kind
of ULF magnetic disturbances should not be taken as a ULF earthquake precursors of the electromagnetic emission at present.
The main features of such signals are as follows: the signals occur discontinuously during storms and the duration of each
time section with such signals and the occurrence rates of the sections and the disturbance amplitudes are usually related
to the types and intensities of storms. The wave form characteristics of the ULF disturbance are also related to the types
of storms. Generally, the amplitudes and durations for SC storms are stronger and longer respectively than those for GC stroms,
and if a storm is with largerK index, then relatively large amplitudes and higher rates and longer durations as well as variable frequencies will be observed
andvice versa. Most of the start time and the time section with strongest disturbance recorded by the ULF unit and by the variometer are
not consistent with each other, and the same one is only about 44%. The periods and intensities of such disturbance signals
are in the ranges of few to several seconds and 0.04–8 nT respectively. The predominant frequency is about 0.06 Hz and certain
energies are also distributed on the harmonic frequencies.
Contribution No. 95A0063, Institute of Geophysics, SSB, China. 相似文献
18.
ＴｈｅｑｕａｌｉｔｙｅｘａｍｉｎａｔｉｏｎｏｆｏｂｓｅｒｖａｔｉｖｅｄａｔａａｔＧｅｏｍａｇｎｅｔｉｃｏｂｓｅｒｖａｔｏｒｉｅｓＡｎ－ＬｏｎｇＣＨＥＮＧ（程安龙），Ｊｉｎ－ＰｉｎｇＺＨＯＵ（周锦屏），Ｙｕ－ＦｅｎＧＡＯ（高玉芬）Ｘｕｅ－ＭｉｎＺＨＡＯ... 相似文献
19.
Estimating external magnetic field differences at high geomagnetic latitudes from a single station 
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下载免费PDF全文 Providing an accurate estimate of the magnetic field on the Earth's surface at a location distant from an observatory has useful scientific and commercial applications, such as in repeat station data reduction, space weather nowcasting or aeromagnetic surveying. While the correlation of measurements between nearby magnetic observatories at low and mid‐latitudes is good, at high geomagnetic latitudes () the external field differences between observatories increase rapidly with distance, even during relatively low magnetic activity. Thus, it is of interest to describe how the differences (or errors) in external magnetic field extrapolation from a single observatory grow with distance from its location. These differences are modulated by local time, seasonal and solar cycle variations, as well as geomagnetic activity, giving a complex temporal and spatial relationship. A straightforward way to describe the differences are via confidence intervals for the extrapolated values with respect to distance. To compute the confidence intervals associated with extrapolation of the external field at varying distances from an observatory, we used 695 station‐years of overlapping minute‐mean data from 37 observatories and variometers at high latitudes from which we removed the main and crustal fields to isolate unmodelled signals. From this data set, the pairwise differences were analysed to quantify the variation during a range of time epochs and separation distances. We estimate the 68.3%, 95.4% and 99.7% confidence levels (equivalent to the 1σ, 2σ and 3σ Gaussian error bounds) from these differences for all components. We find that there is always a small non‐zero bias that we ascribe to instrumentation and local crustal field induction effects. The computed confidence intervals are typically twice as large in the north–south direction compared to the east‐west direction and smaller during the solstice months compared to the equinoxes. 相似文献
20.
Recognition of disturbances with specified morphology in time series: Part 2. Spikes on 1-s magnetograms 总被引：1，自引：0，他引：1
A. A. Soloviev S. M. Agayan A. D. Gvishiani Sh. R. Bogoutdinov A. Chulliat 《Izvestiya Physics of the Solid Earth》2012,48(5):395-409
Preliminary magnetograms contain different types of temporal anthropogenic disturbances: spikes, baseline jumps, drifts, etc. These disturbances should be identified and filtered out during the preprocessing of the preliminary records for the definitive data. As of now, at the geomagnetic observatories, such filtering is carried out manually. Most of the disturbances in the records sampled every second are spikes, which are much more abundant than those on the magnetograms sampled every minute. Another important feature of the 1-s magnetograms is the presence of a plenty of specific disturbances caused by short-period geomagnetic pulsations, which must be retained in the definitive records. Thus, creating an instrument for formalized and unified recognition of spikes on the preliminary 1-s magnetograms would largely solve the problem of labor-consuming manual preprocessing of the magnetic records. In the context of this idea, in the present paper, we focus on recognition of the spikes on the 1-s magnetograms as a key point of the problem. We describe here the new algorithm of pattern recognition, SPs, which is capable of automatically identifying the spikes on the 1-s magnetograms with a low probability of missed events and false alarms. The algorithm was verified on the real magnetic data recorded at the French observatory located on Easter Island in the Pacific. 相似文献