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1.
Geomagnetic Hazards to Conducting Networks 总被引：1，自引：0，他引：1
D. H. Boteler 《Natural Hazards》2003,28(2-3):537-561
Geomagnetic disturbances can disrupt the operation of conductingnetworks, such as power systems, pipelines and communication cables. In power systems,geomagnetically induced currents (GIC) flow to ground through power transformers,disrupting their operation and causing transformer heating, increased reactive power demand,and generating harmonics that can cause relay misoperation. In extreme cases these effectscan lead to power blackouts such as occurred on the Hydro-Québec system during a geomagneticstorm in March 1989 leaving 6 million people without power for 9 hours.Geomagnetic disturbances are the result of eruptions on theSun that send high energy particles streaming out into space. When these particles reach theEarth they interact with the magnetic field, generating currents that flow down into the ionosphere.The most intense currents are associated with the aurora and occur in an east-west bandacross Canada. It is the magnetic field produced by these ionospheric currents that is seen on theground as a magnetic disturbance.Prevention of geomagnetic effects on power systems hasfocussed on blocking the flow of GIC in the system. However, such measures are expensive andmany utilities rely on forecasts of geomagnetic activity to help them operate during disturbances.The Canadian Geomagnetic Forecast Service, operated by Natural Resources Canada,has been in operation since 1974 and now provides long term and short term forecasts for threelatitude regions of Canada.Research is needed on all aspects of the problem; from newinformation about solar eruptions for improving forecasting services; to understanding systemresponse to disturbances. Research on geomagnetic disturbances is conducted by the CanadianGeomagnetic Forecasting Centre and a number of active groups at Canadian universities; whileresearch on geomagnetic effects is conducted by affected industries, often in collaborationwith the forecasting centre. 相似文献
2.
Geomagnetic effects related to the stresses induced by the water load of the Chiotas reservoir (NW Italy) were studied, with measurements of the geomagnetic field at different stages of filling. The highest effect, mean 7 nT, was recorded at three-quarters full; subsequently, as the volume of water increased, the anomalous variations fell to about 2 nT. 相似文献
3.
H. Mavromichalaki M. Papailiou S. Dimitrova E. S. Babayev P. Loucas 《Natural Hazards》2012,64(2):1447-1459
Recent multi-disciplinary heliobiological and biometeorological researches reveal that the human organism is sensitive to environmental physical activity changes and reacts to them through variations of the physiological parameters of the human body. In this study, electrocardiograms of functionally healthy persons, who were digitally registered at the Laboratory of Heliobiology located in the Medical Centre INAM (Baku, Azerbaijan), were studied in relation to different levels of cosmic ray activity and geomagnetic field disturbances. In total, 1,673 daily digital data of heart rate values and time series of beat-to-beat heart rate intervals (RR intervals) were registered for the time period July 15, 2006?CMarch 31, 2008, which includes the period of December 2006, when intense cosmic ray events and strong geomagnetic disturbances occurred. The statistical significance of the influence of geomagnetic activity levels and cosmic ray intensity variations on heart rate and RR intervals was estimated. Results revealed that heart rate increase and RR intervals variations were more pronounced for high levels of geomagnetic activity and large cosmic ray intensity decreases, whereas very small or even minimum cosmic ray intensity variations did not affect heart rate dynamics. Moreover, heart rate increased on the days before, during and after geomagnetic storms with high intensities and on the days preceding, and following cosmic ray intensity decreases. 相似文献
4.
Investigation into possible space weather hazards on cardiovascular system has been performed. A group of 14 healthy volunteers was examined in the spring of 2009 and 2 healthy persons performed electrocardiograph records for a period of 1 year everyday in the morning and in the evening. Results revealed that heart rate variability (HRV) parameters of the group varied strongly from the day before till 3 days after the registered weak storms during the time of investigation. Blood pressure and subjective psychophysiological complaints increased statistically significantly from 0 day till +2nd day. Heart rate (HR) of the group showed a trend for decrease. It was established that morning measurements were more sensitive to space weather variations in comparison with evening measurements. Both persons with prolonged registrations for a period of year did not reveal graded response to geomagnetic storms with different intensities. Both of them decreased HR during moderate storms, but they increased HR during major storms and on the days before and after these storms. HRV parameters varied significantly on these days. 相似文献
5.
G. Cifuentes-Nava J. A. González-Esparza E. Hernández-Quintero A. Lara-Sánchez J. F. Valdés-Galicia 《Earth Science Informatics》2008,1(1):15-19
We present the Virtual Earth-Sun Observatory (VESO) at the web site http://www.veso.unam.mx. This site shows a real time integrated
database obtained from four instruments of the Instituto de Geofisica-UNAM studying Sun-Earth connection phenomena. (1) The
Solar Radio Interferometer (RIS, Radio Interferómetro Solar) measures the lower solar atmosphere radiation at 7.5 GHz, revealing
microwave bursts associated with solar activity. (2) The Mexican Array Radio Telescope (MEXART, Observatorio de Centelleo
Interplanetario de Coeneo) will detect solar wind large-scale disturbances between Sun and Earth (e.g., Interplanetary counterparts
of Coronal Mass Ejections (ICMES) and Stream Interaction Regions (SIR)) employing the interplanetary scintillation technique
(IPS) operating at 140 MHz. (3) The Cosmic Ray Observatory (RC) detects high energy galactic particles, whose flow is affected
by magnetic disturbances in the solar wind, and (4) the Teoloyucan Geomagnetic Observatory (TEO) measures the variations in
the Earths magnetic field. The VESO instruments provide data from four different points of the complex chain of the solar
terrestrial relations and will allow the study of intense solar events causing geomagnetic activity. The VESO project is part
of the celebration of the International Heliophysical Year (IHY) and the Electronic Geophysical Year (EGY) in Mexico. 相似文献
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The results of regular instrumental observations over geomagnetic field variations in the zones of influence of tectonic faults
during movement of seismic waves of varied intensity are presented. It has been shown that seismic waves with an amplitude
more than 5–10 μm/s, traveling across the fault zone, always produced geomagnetic field variations. At weaker seismic disturbances,
geomagnetic field variations are of the “glimmer” character, and the relative frequency of appearance of the effect drops
as the seismic wave amplitude decreases. The quantitative dependence between the maximal value of the full vector of variations
in geomagnetic field induction in a fault zone and the amplitude of the seismic disturbance has been found for the first time. 相似文献
8.
Analysis of experimental observations of the Earth’s magnetic field variations recorded by the scientific instruments at the
Northern Caucasus Geophysical Observatory of the Institute of Physics of the Earth, Russian Academy of Sciences, in the period
2007–2009 was performed. It was found that the characteristic ultra-low-frequency (ULF) waveforms of the geomagnetic disturbances
were distinguished in the structure of the observed variations that reflect the process of preparation and development of
a tsunamigenic earthquake. 相似文献
9.
Ionospheric scintillation observations of VHF radio signals from FLEETSAT satellite (73°E longitude) at Bhopal from January
1990 to December 1990 have been used to study the characteristic variations of scintillation activity. It is found that scintillation
occurrence is essentially a night-time phenomenon and day-time scintillations are very rare. Annual average nocturnal variation
of percentage occurrence of scintillations shows maximum at around 2100–2200 hours LT. Seasonally, scintillations are most
prominent during equinoxes and least during summer. Geomagnetic disturbances tend to decrease the occurrence of scintillations
in the pre-midnight period. 相似文献
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11.
The method of rectangular harmonic analysis is applied to the geomagnetic field data from central India to isolate long wavelength
magnetic anomalies associated with largescale crustal structures. The long-wavelength anomalies have accounted for approximately
20 % of the spatial variability of the residual magnetic field over the International Geomagnetic Reference Field. On the
magnetic anomaly map, reflecting the surface expression of longwavelength anomalies, the Tapi-Narmada-Son zone is characterized
by a feeble positive anomaly bounded by a strong negative anomaly. The anomaly pattern is believed to be caused by the large-scale
undulation in Moho and related variations in the thickness of the lower (basaltic) crust. The other two prominent anomalies,
the magnetic low striking northwest and the magnetic high trending east-northeast, appear to be related to the deep structural
feature of the Godavari graben and the eastern Rajasthan lineament respectively. 相似文献
12.
地磁场数据处理涉及的内容颇多。实际工作中,应该针对地磁场异常特点和需要解决的地质问题,必须抓住数据处理的关键技术。本文通过对已知矿区地磁场数据的曲化平、向下延拓、局部场和背景场的分离等关键技术的应用,结果表明,经三种地磁场数据处理关键技术的应用,取得了良好的地质效果。 相似文献
13.
地球磁场极性在地质历史中发生过相当频繁的倒转。作者将地球内部划分为岩石圈－软流圈－中圈－液圈－固核等5个动力学圈层，认为中圈与固核间可异步旋转；地球偶极磁场由中圈与固核异步旋转时所驱动的液圈中的封闭涡流与系磁场作用产生；该偶极子场极性由地球所通过的银道面上侧或下侧磁场方向及液圈涡流的方向共同决定，二者之一反向，极性发生倒转。 相似文献
14.
为了深入认识与理解南北地震带北段和蒙古中部大陆强震孕育与发生的深部构造环境,在南北纵贯蒙古国全境的苏赫巴托尔—乌兰巴托—达兰扎达嘎德剖面上开展了大规模重磁测量及岩石样品采集。笔者系统地分析与总结了剖面上585块岩石样品的密度、磁化率和天然剩余磁化强度等物性参数。结果表明,整个剖面以火成岩为主,沉积岩为辅,仅有少量变质岩出露,且各岩石大类、类和亚类以及各年代地层之间,均存在着不同程度的密度与磁性差异。火成岩磁化率和天然剩余磁化强度分别具有3~5个数量级差异,密度变化范围较大;而沉积岩磁化率和天然剩余磁化强度相对较弱。一方面,物性差异为利用重磁测量开展剖面地壳结构的反演与研究奠定了基础;另一方面,这些物性参数为相关地球物理测量数据的反演与解释提供了重要约束。 相似文献
15.
The results of instrumental observations have shown that the spectra of geomagnetic variations exhibit a quasi-harmonic component, the frequency of which is close to the basic spheroidal mode of the Earth 0S2. In periods 15 days long after three large earthquakes and in the absence of strong magnetic disturbances, the fine structure of this mode in geomagnetic variations is identified in the form of singlets. The frequencies of these singlets are similar to the theoretical values calculated using an ideal elastic isotropic model of the Earth of spherical symmetric form without its rotation.
相似文献16.
E. Giannaropoulou M. Papailiou H. Mavromichalaki M. Gigolashvili L. Tvildiani K. Janashia P. Preka-Papadema Th. Papadima 《Natural Hazards》2014,70(2):1575-1587
Over the last few years, various researches have reached the conclusion that cosmic ray variations and geomagnetic disturbances are related to the condition of the human physiological state. In this study, medical data concerning the number of incidents of different types of cardiac arrhythmias for the time period 1983–1992, which refer to 1902 patients in Tbilisi, Georgia, were used. The smoothing method and the Pearson r-coefficients were used to examine the possible effect of different solar and geomagnetic activity parameters and cosmic ray intensity variations on the different types of arrhythmias. The time interval under examination was separated into two different time periods, which coincided with the polarity reversal of the solar magnetic field occurred in the years 1989–1990, and as a result, a different behavior of all the above-mentioned parameters as well as of the different types of arrhythmias was noticed during the two time intervals. In addition, changing of polarity sign of the solar magnetic field was found to affect the sign of correlation between the incidence of arrhythmias and the aforementioned parameters. The primary and secondary maxima observed in the solar parameters during the solar cycle 22, also appeared in several types of arrhythmias with a time lag of about 5 months. 相似文献
17.
Weijia Zhang Yuanlin Sun Neil Kelley Yang Lei Hangjie Yu 《Russian Geology and Geophysics》2012,53(5):491-499
Growth lines in the mineralized tissues of living and fossil organisms often exhibit regular patterns that record daily, monthly, or annual cycles. Growth laminations in fossil corals and other marine invertebrates indicate long-term deceleration of the Earth’s rotation, probably largely due to tidal friction, resulting in a decline in the number of days per year over the Earth’s history. Fossils suggest the rate of decline has not been uniform, with the trend between the late Carboniferous and Cretaceous in particular departing from preceding and subsequent periods. However, insufficient data have obscured the nature and cause of the apparent halt in despinning within this time interval. Here we present new fossil geochronometer data that reveal a sustained acceleration in the Earth’s rotation in the early Mesozoic Era, lasting about 90 million years and producing a decrease in the length of day (LOD) at an average rate of about 3 ms/cy. The coincidence of this acceleration with certain geophysical events including the final assembly of Pangaea and a change in the intensity and stability of the geomagnetic field strongly suggests that its cause is rooted in the deep interior of the Earth. A similar explanation has been proposed for observed decadal variations in the Earth’s rotation. Our results suggest large-scale linkage of rotational variation, tectonics, and the geomagnetic field to core–mantle boundary (CMB) dynamics. Furthermore the newly identified acceleration in the Earth’s rotation which began at the end of the Paleozoic, and the geophysical factors that are associated with it, can ultimately bear on the causal mechanisms behind the Permo-Triassic mass extinction. 相似文献
18.
Dating of palaeomagnetic records from Finnish lake sediment cores using pollen analysis 总被引：1，自引：0，他引：1
Pertti Huttunen Julie Stober 《Boreas: An International Journal of Quaternary Research》1980,9(3):193-202
Palaeomagnetic and palynological studies have been made of the sediments of two Finnish lakes. Geomagnetic field changes in Finland can be traced since lake sediments record the ambient geomagnetic field at, or close to, the time they are deposited. Pollen analyses provided a useful method of dating these changes since 14 C dates proved to be misleading. 相似文献
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20.
C. Panneerselvam C. Selvaraj K. Jeeva K. U. Nair C. P. Anilkumar S. Gurubaran 《Journal of Earth System Science》2007,116(3):179-186
Surface measurements of the atmospheric electrical parameters like Maxwell current, electric field and conductivity studied
at the Indian station, Maitri (70.75° S, 11.75° E, 117 m above mean sea level), Antarctica, during austral summer have been
analyzed for the years 2001 to 2004. A total of 69 days were selected which satisfied the ‘fairweather’ conditions, i.e.,
days with absence of high winds, drifting or falling snow, clouds, and fog effects. The diurnal variation curve of electric
field and vertical current averaged for 69 fairweather days is a single periodic with a minimum at 03:00 UT and a maximum
near 19:00 UT, which is very similar to the Carnegie curve. The correlation coefficient between these measured parameters
has a high value (more than 0.9) for all the days. During fairweather days the measured current and field variations are similar
and hence it is clear that the conductivity is more or less stable. During magnetically disturbed days, the dawn-dusk potential
drop has clear influences on the diurnal variation and it modifies the conductivity. Apart from the day-to-day variation in
low latitude thunderstorm activity, there are diurnal, seasonal, inter-annual variations in the electric potential and the
currents, as well as solar influences on the measured parameters. This study will help us to examine the impact of solar and
geophysical phenomena like solar flares, geomagnetic storms and substorms on the global electric circuit. 相似文献