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1.
Due to several complexities associated with the equatorial ionosphere, and the significant role which the total electron content (TEC) variability plays in GPS signal transmission, there is the need to monitor irregularities in TEC during storm events. The GPS SCINDA receiver data at Ile-Ife, Nigeria, was analysed with a view to characterizing the ionospheric response to geomagnetic storms on 9 March and 1 October 2012. Presently, positive storm effects, peaks in TEC which were associated with prompt penetration of electric fields and changes in neutral gas composition were observed for the storms. The maximum percentage deviation in TEC of about 120 and 45% were observed for 9 March and 1 October 2012, respectively. An obvious negative percentage TEC deviation subsequent to sudden storm commencement (SSC) was observed and besides a geomagnetic storm does not necessarily suggest a high scintillation intensity (S4) index. The present results show that magnetic storm events at low latitude regions may have an adverse effect on navigation and communication systems. 相似文献
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M. G. Deminov A. V. Belov E. V. Nepomnyashchaya V. N. Obridko 《Geomagnetism and Aeronomy》2018,58(4):501-508
Equations of regression are derived for the intense magnetic storms of 1957?2016. They reflect the nonlinear relation between Dstmin and the effective index of geomagnetic activity Ap(τ) with a timeweighted factor τ. Based on this and on known estimations of the upper limit of the magnetic storm intensity (Dstmin =–2500 nT), the maximal possible value Ap(τ)max ~ 1000 nT is obtained. This makes it possible to obtain initial estimates of the upper limit of variations in some parameters of the thermosphere and ionosphere that are due to geomagnetic activity. It is found, in particular, that the upper limit of an increase in the thermospheric density is seven to eight times larger than for the storm in March 1989, which was the most intense for the entire space era. The maximum possible amplitude of the negative phase of the ionospheric storm in the number density of the F2-layer maximum at midlatitudes is nearly six times higher than for the March 1989 storm. The upper limit of the F2-layer rise in this phase of the ionospheric storm is also considerable. Based on qualitative analysis, it is found that the F2-layer maximum in daytime hours at midlatitudes for these limiting conditions is not pronounced and even may be unresolved in the experiment, i.e., above the F1-layer maximum, the electron number density may smoothly decrease with height up to the upper boundary of the plasmasphere. 相似文献
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The coupled ionosphere–thermosphere–plasmasphere system is very complex. The study of its interrelationships during geomagnetically disturbed conditions is an especially challenging task.Significant progress has been achieved during the last few years in developing comprehensive theoretical models to describe its global behaviour.Moreover, more simple, specialized numerical modelling of some specialaspects of storm behaviour and/or regional models have contributedto the progress in this field.This paper summarizes recent developments in upper ionosphereand plasmasphere storm studies and modelling.From an observational point of view the upper ionosphere/plasmasphereregion is well reflected in radio beacon measurements providing the totalelectron content (TEC). The development of space-based radio navigation systems such as GPS offersnew opportunities to derive TEC on both regional and global scale.Combining TEC with ionosonde data enables the variability of the shape of the electron density distribution during storms to be studied.We present some examples of co-ordinated investigation,made during the CEDAR storm study intervals. 相似文献
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Geomagnetism and Aeronomy - The mechanism of the generation of the geomagnetic field disturbance accompanying tsunami wave propagation is considered. Electric currents in the marine environment and... 相似文献
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Geomagnetism and Aeronomy - The influence of geomagnetic activity on slips of navigation signals of the global positioning system (GPS), as well as an increase in the amplitude of jumps in the... 相似文献
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Falayi E. O. Ajose A. S. Roy-Layinde T. O. Adewole A. T. 《Geomagnetism and Aeronomy》2021,61(8):1221-1233
Geomagnetism and Aeronomy - The geomagnetic disturbance associated with coronal mass ejections (CMEs) of September 8, 2017 was evaluated using the time derivatives of the horizontal geomagnetic... 相似文献
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美国利用IMAGE卫星的极紫外辐射(EUV)探测器对地球等离子体层进行了连续5年的遥感成像观测。由于IMAGE卫星数据是沿观测路径上的积分投影数据,并且存在地球“遮挡”、“阴影”、“数据缺失”等问题,无法直接利用传统的CT方法对等离子体层进行三维重建。本文利用地球磁场模型,基于地球等离子体层的物理性质,建立一个联系地球磁赤道面密度与投影数据的EUV成像模型,实现了从单个角度的EUV观测图像进行地球等离子层三维重构的方法。 相似文献
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Geomagnetism and Aeronomy - Ionospheric anomaly crest regions are most challenging for scientific community to understand its mechanism and investigation, for this purpose we are investigating some... 相似文献
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Gromova L. I. Kleimenova N. G. Gromov S. V. Malysheva L. M. 《Geomagnetism and Aeronomy》2020,60(5):547-558
Geomagnetism and Aeronomy - The behavior of geomagnetic disturbances during a moderate CIR storm, the most intense magnetic storm of 2009 in the solar activity minimum are considered. It is... 相似文献
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Geomagnetism and Aeronomy - The response of strong magnetic storms in variations of the electric field of the near-ground atmosphere of the midlatitudes are studied according to data from long-term... 相似文献
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选取广东省数字化地磁观测以来的地磁资料和一定震中距的显著地震事件,计算地震前1~2年的地磁垂直分量加卸载响应比,结果显示,显著地震前1个月至1年不等,地磁加卸载响应比值有明显超经验阈值2.8的现象。 相似文献
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Diana Prado Garzón Christiano G.M. Brum Ezequiel Echer Néstor Aponte Michael P. Sulzer Sixto A. González Robert B. Kerr Lara Waldrop 《Journal of Atmospheric and Solar》2011,73(11-12):1568-1574
We analyze the data obtained using the Arecibo incoherent scatter radar to examine the response of the topside ionosphere to a moderate geomagnetic storm that occurred during the period March 7–11, 2008. During this time period a magnetic storm with a non-monotonic main phase decrease in the Dst index occurred. The recovery phase also exhibited a secondary Dst decrease. During the initial phase of the storm, Te and Ti increased coincident with the arrival of the solar wind. The main phase registered an increase in proton concentration proportional to Ne while temperatures reached the lowest values. Variations in O+ concentration were not significant but a reduction in helium fraction was observed. Soon after the peak of the storm, the transition height between the topside ionosphere and the protonosphere, where H+ ions dominate composition, was lower than would be expected during quiet conditions and this behavior lasted for approximately 12 h. 相似文献
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非线性理论的一些主要方法:分形分维、人工神经网络、小波分析等。在地磁学科研究中得到较广泛的应用。本文是对“非线性方法在地球物理研究中的应用综述和展望”一文的补充,本文主要综述了国内外地磁学(包括空间物理)学者应用非线性方法的情况,提出了一些本人认为应该注意的问题。 相似文献
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减小直流输电对地磁观测影响的几种办法 总被引:2,自引:0,他引:2
随着经济建设的飞速发展,地震监测环境的保护越来越困难。各种干扰因素不断出现,有些干扰影响范围较小,可以设法避开;有些干扰影响范围较大,几乎无法躲避。直流输电对地磁观测产生的干扰其影响范围特别广,幅度特别大。我国于1989年建成了葛洲坝至上海南桥的±500KV~200A高压直流输电工程。2002年12月份从三峡至武进政平的±500KV~3000A直流输电工程也开始进入测试阶段,并于2003年7月开始正式运行。随着“西电东送”战略的确定,以后会有更多条超高压直流输电线路将建成(龚大卫等,2000;陈红军等,2001;吴元熙等,2000)。其中三峡至武进政平的… 相似文献
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Xu Chunrong Lin Yunfang Lu Guifang Zhao Ming Li Shengxiang Gou Xianbin Yu Jingzhong and Zeng XiaopingInstitute of Crustal Dynamics CSB Beijing China Institute of Geophysics CSB Beijing China Seismological Bureau of Yunnan Province Kunming China Seismological Office of Chongqing Municipality Chongqing China 《中国地震研究》1998,(4)
Many earthquakes occurred during the period 1994 -1996 in Sichuan and Yunnan Provinces, Southwest China. Taking the process of the initial main phase recovery phase of the magnetic storm as the process of load-unload response of the geomagnetic field to the solar wind, we have estimated and analyzed the distribution in time and space of the load-unload response ratio P(z) of the storm time disturbance daily variation of the vertical component Z of the geomagnetic field at ten stations in Southwest China. We found that the area with high ratio P(z) was just the area where moderately strong earthquakes would occur from 44 days to 15 months later. The relationship between the high ratio P(z) and weather disasters in both seismic and non-seismic areas is discussed briefly. 相似文献
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Marc A. Vallée Larry Newitt Ian R. Mann Mouhamed Moussaoui Régis Dumont Pierre Keating 《Pure and Applied Geophysics》2007,164(1):161-176
Geomagnetic activity affects aeromagnetic surveys. Geomagnetic variations are quite complex and can be quantified in different
ways. A measure of geomagnetic activity that is useful for planning aeromagnetic surveys is the Pc3 pulsation index developed
by the Australian Space Weather Agency. Purposeful to developing guidelines for planning aeromagnetic surveys in Canada, we
study the variations in Pc3 index amplitude over Canada in 2000. This study shows distinct patterns associated with the sub-auroral
zone, the auroral zone, and the polar cap. Average Pc3 index activity is higher during the months of February, July, September,
and November in the auroral and sub-auroral zones. The station in the polar cap exhibits maximum activity near midday during
the summer months. Detailed analysis of a magnetic storm shows that Pc3 index amplitude during the beginning of the solar
storm is least important at the polar cap. The mean Pc3 index also relates to solar wind parameters such as the solar wind
velocity and the vertical polarity of the interplanetary magnetic field. Analysis of the morning maximum of the Pc3 index
observed in the auroral zone can be used to develop guidelines for planning aeromagnetic surveys in Canada and other areas
of the world affected by auroral zones. 相似文献