共查询到20条相似文献，搜索用时 31 毫秒
1.
Yu. P. Tsvetkov O. M. Brekhov T. N. Bondar S. V. Filippov V. G. Petrov N. M. Tsvetkova A. Kh. Frunze 《Geomagnetism and Aeronomy》2014,54(2):263-268
Two global analytical models of the main magnetic field of the Earth (MFE) have been used to determine their potential in deriving an anomalous MFE from balloon magnetic surveys conducted at altitudes of ～30 km. The daily mean spherical harmonic model (DMSHM) constructed from satellite data on the day of balloon magnetic surveys was analyzed. This model for the day of magnetic surveys was shown to be almost free of errors associated with secular variations and can be recommended for deriving an anomalous MFE. The error of the enhanced magnetic model (EMM) was estimated depending on the number of harmonics used in the model. The model limited by the first 13 harmonics was shown to be able to lead to errors in the main MFE of around 15 nT. The EMM developed to n = m = 720 and constructed on the basis of satellite and ground-based magnetic data fails to adequately simulate the anomalous MFE at altitudes of 30 km. To construct a representative model developed to m = n = 720, ground-based magnetic data should be replaced by data of balloon magnetic surveys for altitudes of ～30 km. The results of investigations were confirmed by a balloon experiment conducted by Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation of the Russian Academy of Sciences and the Moscow Aviation Institute. 相似文献
2.
The technique for determining the normal and anomalous magnetic fields from magnetovariation observations has been applied to the measurements on the SP19 drifting station. As a result, the regional profile of three magnetic field components has been obtained to an accuracy considerably exceeding the accuracy of other methods of marine magnetic survey. These data make it possible to estimate the geometrical parameters of the Earth’s crust blocks composing the Lomonosov Rise. 相似文献
3.
O. Troshichev 《Journal of Atmospheric and Solar》2010,72(13):943-950
The paper demonstrates the close relationships between the polar cap magnetic activity, which is characterized by PC index (Troshichev et al., 1988, Troshichev et al., 2006) and some atmospheric phenomena typical of the winter Antarctica, such as enhancement of cloudiness, sudden warmings of the ground atmosphere in near-pole area, and formation of anomalous wind regimes above Antarctica. It was shown previously (Troshichev et al., 2004, Troshichev et al., 2008, Troshichev and Janzhura, 2004) that these atmospheric phenomena are controlled by variations of the geoeffective interplanetary electric field impacting the Earth’s magnetosphere. On the other hand, the polar cap magnetic activity is also determined by the interplanetary electric field influence through the field-aligned magnetospheric currents and electric field in the polar cap ionosphere. The results imply that the PC index, available online at http://www.aari.nw.ru from the near-pole station Vostok, can be used to monitor the anomalous atmospheric processes in winter Antarctica. 相似文献
4.
V. V. Adushkin A. A. Spivak S. B. Kishkina D. N. Loktev S. P. Solov’ev 《Izvestiya Physics of the Solid Earth》2006,42(7):567-584
Results of various instrumental observations of geodynamic processes in the Earth’s crust and geophysical fields at the crust-atmosphere boundary in the Oka area of the Nelidovo-Ryazan tectonic structure and adjacent fractures and in the zone of the Gornyi Altai earthquake of September 27, 2003, are presented. The correlations between the geophysical fields are determined from the results of processing and analysis of microseismic vibrations, the emanation field of natural radon, and variations in the electric field in ground and the magnetic field in the surface atmospheric layer. Tidal deformations of the crust were considered as external effects enhancing the interactions between the geospheres. It is noted that tectonic faults determining the block structure of the crust are recognizable as anomalous variations in the geophysical fields and their high cross-correlation. 相似文献
5.
Magnetic Pulsations: Their Sources and Relation
to Solar Wind and Geomagnetic Activity 总被引：1，自引：1，他引：0
Ultra low frequency (ULF) waves incident on the Earth are produced by processes in the magnetosphere and solar wind. These
processes produce a wide variety of ULF hydromagnetic wave types that are classified on the ground as either Pi or Pc pulsations
(irregular or continuous). Waves of different frequencies and polarizations originate in different regions of the magnetosphere.
The location of the projections of these regions onto the Earth depends on the solar wind dynamic pressure and magnetic field.
The occurrence of various waves also depends on conditions in the solar wind and in the magnetosphere. Changes in orientation
of the interplanetary magnetic field or an increase in solar wind velocity can have dramatic effects on the type of waves
seen at a particular location on the Earth. Similarly, the occurrence of a magnetospheric substorm or magnetic storm will
affect which waves are seen. The magnetosphere is a resonant cavity and waveguide for waves that either originate within or
propagate through the system. These cavities respond to broadband sources by resonating at discrete frequencies. These cavity
modes couple to field line resonances that drive currents in the ionosphere. These currents reradiate the energy as electromagnetic
waves that propagate to the ground. Because these ionospheric currents are localized in latitude there are very rapid variations
in wave phase at the Earth’s surface. Thus it is almost never correct to assume that plane ULF waves are incident on the Earth
from outer space. The properties of ULF waves seen at the ground contain information about the processes that generate them
and the regions through which they have propagated. The properties also depend on the conductivity of the Earth underneath
the observer. Information about the state of the solar wind and the magnetosphere distributed by the NOAA Space Disturbance
Forecast Center can be used to help predict when certain types and frequencies of waves will be observed. The study of ULF
waves is a very active field of space research and much has yet to be learned about the processes that generate these waves. 相似文献
6.
The generation of auroral kilometric radiation in a narrow 3D plasma cavity, in which a weakly relativistic electron flow is propagated along the magnetic field against a low-density cold background plasma, is studied. The time dynamics of the propagation and intensification of waves are analyzed using geometric optics equations. The waves have different wave vector components and start from the cavity center at an altitude of about the Earth’s radius at plasma parameters typical for the auroral zone at this altitude. It is shown that the global inhomogeneity of the Earth’s magnetic field is of key importance in shaping the auroral kilometric radiation spectra. 相似文献
7.
Summary The paper presents comprehensive theory based on the boundary integral method for calculations of the electric potential,
electric field and corresponding magnetic field due to a pair of D.C. source electrodes near a vertical resistivity contact
in the halfspace, indlucing a 3-D disturbing body in the vicinity of the contact. Special attention is paid to the case when
the disturbing body touches the vertical contact. Results of numerical calculations are presented in the form of sounding
curves and a set of isoline graphs for potential, components of the electric and magnetic field (total and anomalous) on the
surface of the Earth. It is shown that the presence of the disturbing body at the contact is most pronounced in the electrical
characteristics. Anomalies in the magnetic field are small in comparison to the field due to the electric current in the electrode
cable and primary currents flowing from the electrodes. 相似文献
8.
在简化条件下, 估计了压磁效应的可能量级.由此推知, 在非磁异常区, 地震前后的磁场变化不一定是压磁效应引起的.压磁效应不是震磁关系的唯一机制.按照渗滤电流理论推出的公式表明, 由地下水渗滤作用引起的所谓膨胀磁效应也是很小的.只有渗滤区足够大, 地下水剧烈运动, 才有可能观测到膨胀磁效应. 相似文献
9.
L. E. Sobisevich E. A. Rogozhin A. L. Sobisevich To Shen Ziao Liu 《Seismic Instruments》2017,53(1):28-45
The paper presents results of instrumental observations of seismic processes and variations in the Earth’s magnetic field at the stages of nucleation and development of earthquakes in the Chinese provinces of Qinghai, Sichuan and Yunnan. Data on manifestations of all these strong seismic events are indicated. Monitoring of the changes in the magnetic field is based on data obtained at the Northern Caucasus Geophysical Observatory, IPE RAS and integrated observation points of the Institute of Terrestrial Magnetism, the Ionosphere and Radio Wave Propagation, RAS (IZMIRAN). The experimental results have allowed us to represent the structure of induced anomalous geomagnetic disturbances, which can be associated with the development of related geodynamic processes in the geological medium of the seismic source zone. 相似文献
10.
K. Prikner 《Annales Geophysicae》1997,15(6):645-655
The spectra of three series of simultaneous ground (Budkov Observatory) and satellite (Freja) ULF measurements have been processed. The following features were studied in the FFT spectra, power-spectra and cross-spectra of the six-minute samples, recorded during quasi-conjugate approaches of Freja to the local Budkov magnetic field line: (a) the Doppler frequency shift (about 1 mHz and less) in the predominant and some particular spectral components on Freja; (b) the amplitude relations between the ground and satellite (ratios 0.3 to 0.8); (c) phase shifts between particular signal components on the spacecraft above the ionosphere (in the azimuthal y-direction on Freja) and on the ground (in the meridional x-direction at Budkov) have been estimated (phase lags on the ground 0.9 rad) and (d) also dynamical characteristics of the fundamental wave modes in the (x,y)-plane, perpendicular to the magnetic field line, have been estimated for the predominant spectral components, considering standing oscillation along the field line. Azimuthal wave numbers were about 2.0, propagating northwest at 400km/s. 相似文献
11.
M. N. Ramanaiah Chowdary 《Pure and Applied Geophysics》1971,92(1):139-149
Summary Not infrequently, in mining geophysics, the anomalous field of the magnetized body is appreciably large and it varies from the direction of the earth's normal field within the vicinity of the magnetized body. Total magnetic intensity data collected on the ground over shallow magnetized bodies cannot be interpreted quantitatively, since all the available methods of interpretation assume that the resultant field lies in the direction of earth's normal field as the anomalous field is small. For geological bodies that can be magnetically represented by infinite line pole, point pole, infinite line dipole, and point dipole, this paper gives quantitative interpretation procedures for total magnetic intensity anomalies without the above assumption using the characteristic points from the theoretical curves (not reproduced). These characteristic curves can be used for the direct determination of depths and offsets by using information from suitably chosen field profiles.Contribution No. N.G.R.I.-71-233. 相似文献
12.
对于电磁卫星所观测到的地震震前电磁异常现象的机制,即电磁异常如何从岩石圈穿过大气层耦合到电离层及其以上空间,目前仍是尚未解决的问题.本文主要介绍目前大量有关地震岩石圈异常的机制研究,力图从卫星地震电磁异常的源头—岩石圈地震来获得相关认识.岩石圈地震前兆异常包括：地表变形、水位变化、悬浮薄雾、超低频（ULF）电磁异常、山脊或山顶发光闪电、卫星红外图片大范围数度温度异常、磁场高于地磁偶极场的0.5%、电离层等离子体密度变化、动物奇异行为等.人们提出了许多试图解释各种异常现象的假说,如热耦合假说、气泡运移假说、边界位错充电假说、离子空穴运移假说等.本文希望通过对以上各种假说提出的基础、物理机理以及异常现象解释的探讨,促进对岩石圈地震前兆异常现象机理认识,从而为地震电磁异常的正确认识提供更有力的帮助. 相似文献
13.
ELECTROMAGNETIC ANOMALOUS PULSES BEFORE AND AFTER EARTHQUAKES(M>6.0) IN CHINA CONTINENT IN 2008 
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下载免费PDF全文 In this paper,we provided the electromagnetic anomaly phenomena prior to five earthquakes with magnitude MW>6.0 occurring in China continent in 2008.The electromagnetic data in frequency bands 800~0.1Hz are recorded at two stations located in Urumqi,Xinjiang Uygur Autonomous Region (URQ) and Tonghai,Yunnan Province (TH).The time series of four horizontal components of the electromagnetic field at the stations are converted to the spectra using Fast Fourier Transform.The relationship between the electromagnetic anomalous phenomena and the earthquake events is studied through analyzing the temporal variation of electromagnetic spectra and comparing them with earthquake events.This study provides the new examples for electromagnetic anomaly phenomena before the earthquakes.The following features can be found.①The obvious anomalous power spectrum density (PSD) of electromagnetic fields in frequency band of 128~0.5Hz appeared before earthquakes.The anomalous PSD is related to the earthquake magnitude and the epicenter distance.The anomaly size of magnetic PSD is about 1-3 orders of magnitude bigger than the background field before Wenchuan MS8.0 earthquake.② The changes of parameters are also related with frequency of the signal;The ELF signal strength observed at seismic stations is significantly related with distance between the stations or the measured magnetic and electrical field components and the source of earthquake.We also found that the field strength attenuated faster in area closer to the source than in far area.It is clear that the magnetic signals have higher signal noise ratio than the electric data.③ The amplitudes are also related with the azimuth of the earthquake to station and with the frequency of the data.④ The anomalous pulses showed cluster phenomenon in time. 相似文献
14.
15.
A numerical simulation study of the ultra-low frequency (ULF) H-component magnetic field at the Earth’s surface arising from a perturbation ionospheric Hall current has been developed. The Hall current system is driven by field-aligned currents (FACs) associated with shear Alfvén field line resonances (FLRs) driven by fast mode global cavity oscillations. The ionospheric phase mixing of the Hall current manifests itself in a number of ways in the ground field, these are: (i) Smoothing the spectral maxima of the ground signal: (ii) Loss in clarity of the harmonic structure of the spectra: (iii) A small increase in the damping rate of the ULF wave at the resonance latitude and (iv) small localised minimum in the spectra at the resonance latitude. 相似文献
16.
The dynamics of the magnetospheric magnetic field during the magnetic storms of different intensity has been studied. The magnetic field variations on the Earth’s surface were calculated using the paraboloid model of the magnetosphere, taking into account the induction currents flowing in the diamagnetically conductive Earth. Dst and its components have been calculated for ten magnetic storms. It has been indicated that relative contributions of magnetospheric sources to Dst change depending on the storm power. For weak and moderate storms, the contribution of the magnetotail current sheet can reach values comparable with the ring current contribution and, sometimes, can even exceed this contribution. For strong storms, the ring current field dominates over the tail current field, the absolute value of which does not exceed 150 nT (also achieved during less intense storms). For storms with minimum Dst exceeding-200 nT, the tail current field is saturated, whereas the ring current can continue developing. 相似文献
17.
V. V. Adushkin A. A. Spivak V. A. Kharlamov 《Izvestiya Physics of the Solid Earth》2018,54(6):859-871
The results of processing and analyzing the instrumental observations of the Earth’s magnetic field at the Geophysical Observatory Mikhnevo of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IGD RAS) for 2010–2015 are presented. Quasi-harmonic components with the periods close to the lunar–solar tidal waves are revealed in the spectra of geomagnetic variations over a period of 0.4 to 30 days. The elliptical S1 tidal wave which is detected in the geomagnetic variations has modulations with periods of 1/3, 1/2, and 1 year. The spectra of the geomagnetic variations contain peaks corresponding to the free oscillations of the Earth. The analysis of the time series of the magnetic field for the period of the strong earthquakes in the absence of geomagnetic disturbances revealed the fine structure of the Earth’s fundamental spheroidal mode 0S2, which splits into five singlets. The established features of the spectrum of geomagnetic variations are helping the development of the new method for studying the deep structure of the Earth and the properties of the inner geospheres for estimating the viscosity of the Earth’s outer core and dynamics of the current systems in the outer (liquid) core, as well as for exploring, with the use of empirical data, the general regularities governing the regimes of energy exchange processes in the geospheres. 相似文献
18.
Induced magnetic fields in the Earth arise due to two phenomena: induction generated by the time-variable exciting field and the motional induction caused by movement of the conductive planet in the outer magnetic fields. The comparison of both approaches on the spherical Earth has been analyzed in the present work for two sources in the ionosphere and magnetosphere. For this aim, both sources with their natural sizes and positions have been modeled analytically to obtain the fields on the layered sphere at the middle latitudes. The conditions when the steady ring current field is not influenced by the Earth’s rotation have been established theoretically. The synthetic diurnal magnetograms were used for the deep sounding by the magnetovariation spatial gradient method and the result was compared with the one obtained on the nonrotating sphere. Sounding results using both approaches were found different above the 2D inhomogeneous mantle. The precessions of the magnetospheric belt current pole for daily sampling frequency were presented using several geomagnetic observatory data in the northern hemisphere. 相似文献
19.
20.
V. N. Koneshov V. B. Nepoklonov V. V. Pogorelov V. N. Solov’ev L. V. Afanas’eva 《Izvestiya Physics of the Solid Earth》2016,52(3):443-451
The application of the airborne gravimetry method for gravity measurements in the Arctic is considered. This method has been extensively employed in foreign studies for determining the figure of the Earth in high-latitude conditions. The possibility of conducting comparative studies along the extensive survey lines and the necessity of aerogravimetry studies for improving the global Earth’s gravity field (EGF) models are discussed. The possibility of the efficient application of the modern EGF models for estimating the systematical errors for different types of gravimetry surveys and exploring the influence of the anomalous far-zone field in the calculations of the plumb line deviations is demonstrated. 相似文献