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1.
《Journal of Atmospheric and Solar》1999,61(3-4):299-307
Measurements at GPS ground stations of the International GPS Service (IGS) havebeen used to derive the total electron content (TEC) of the ionosphere over Europe and overthree North American stations for the 6–11 January 1997 storm event. The derived TEC dataindicate large deviations from the average behaviour especially at high latitudes on thenight-side/early morning longitude sector.The high-latitude perturbation causes a well-pronounced positive phase on the day-sidesector over Europe.Both meridional winds as well as transient electric fields are assumed to contribute to thesignature of the ionospheric perturbation propagating from high to low latitudes. Theobservations indicate a subsequent enhanced plasma loss which is probably due to theequatorward expansion of storm induced composition changes. 相似文献
2.
The structure of the mid- and high-latitude ionosphere during the November 2004 storm event obtained from GPS observations 总被引：1，自引：1，他引：1
Andrzej Krankowski Irk I. Shagimuratov Lubomir W. Baran Galina Yakimova 《Acta Geophysica》2007,55(4):490-508
GPS data from the International GNSS Service (IGS) network were used to study the development of the severe geomagnetic storm
of November 7–12, 2004, in the total electron content (TEC) on a global scale. The TEC maps were produced for analyzing the
storm. For producing the maps over European and North American sectors, GPS measurements from more than 100 stations were
used. The dense network of GPS stations provided TEC measurements with a high temporal and spatial resolution. To present
the temporal and spatial variation of TEC during the storm, differential TEC maps relative to a quiet day (November 6, 2004)
were created.
The features of geomagnetic storm attributed to the complex development of ionospheric storm depend on latitude, longitude
and local time. The positive, as well as negative effects were detected in TEC variations as a consequence of the evolution
of the geomagnetic storm. The maximal effect was registered in the subauroral/auroral ionosphere during substorm activity
in the evening and night period. The latitudinal profiles obtained from TEC maps for Europe gave rise to the storm-time dynamic
of the ionospheric trough, which was detected on November 7 and 9 at latitudes below 50°N. In the report, features of the
response of TEC to the storm for European and North American sectors are analyzed. 相似文献
3.
E. L. Afraimovich S. V. Voeykov N. P. Perevalova K. G. Ratovsky 《Geomagnetism and Aeronomy》2006,46(5):603-608
The intensity of large-scale traveling ionospheric disturbances (LS TIDs), registered according to measurements of the total electron content (TEC) during the magnetic storms of October 29–31, 2003, and November 7–11, 2004, has been compared with that of local electron density disturbances. The data of TEC measurements at ground-based GPS receivers located near the ionospheric stations and the corresponding values of the critical frequency of the ionospheric F region (foF2) were used for this purpose. The variations in TEC and foF2 were similar for all events mentioned above. The previous assumption that the region of thickness 150–200 km in the vicinity of the ionospheric F region mainly contributes to TEC modulation was confirmed for the cases when the electron density disturbance at an F region maximum was not more than 50%. However, this region probably becomes more extensive in vertical when the electron density disturbance in the vicinity of the ionospheric F region is about 85%. 相似文献
4.
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
5.
电离层总电子含量(TEC)是空间天气研究和监测预报的重要参量.本文引入了电离层TEC扰动指数DI, 对青岛等6个台站的DI数据进行分析,选取DI>0.35(DI≤-0.30)作为正(负)相电离层TEC扰动的强度标准,并以连续6 h及以上的DI满足该值来判定电离层TEC暴扰动事件.对电离层TEC暴扰动事件的统计分析表明,在地方时日落后至子夜前为发生高峰时段,正(负)相暴扰动事件平均持续时间约为10.9 h(10.5 h),正相暴发生率以冬季为多,夏季为少,而负相暴则以夏季略高.发现位于赤道异常驼峰区的广州站和位于高中纬度的海拉尔站比典型中纬地区的北京站电离层TEC暴扰动更易发生,且低纬地区以正相暴扰动为主.分析表明,约有70%的电离层TEC暴扰动伴随着有地磁扰动,但是电离层TEC暴扰动并不完全由地磁扰动所引起,强烈气象活动等局地环境因素也可能对电离层TEC暴扰动有着重要影响. 相似文献
6.
Effects of ionospheric horizontal gradients on differential GPS 总被引：2，自引：0，他引：2
This paper outlines the effect of horizontal ionospheric gradients on transionospheric path propagation such as for the case
of GPS signals. The total electron content (TEC) is a function of time of day, and is much influenced by solar activity and
also the receiving station location. To make the model applicable for long baselines, for which the ionosphere is not generally
well correlated between receiving stations, the ionospheric gradients should be taken into account. In this work the signal
path is determined using a modified ray-tracing technique together with a homing-in method. Results show that horizontal gradients
can have a significant effect on GPS positioning for both single station positioning and differential GPS. For differential
GPS, the ionospheric delay can, however, be either increased or decreased compared with the case of no gradient, depending
on the gradient direction. 相似文献
7.
N. M. Polekh O. M. Pirog S. V. Voeikov P. V. Tatarinov A. E. Stepanov V. V. Bychkov Z. F. Dumbrava 《Geomagnetism and Aeronomy》2006,46(5):593-602
Results of the studies of ionospheric parameter variations during the intense geomagnetic storm on November 7–11, 2004, in the 20°–80° N, 60°–180° E sector are presented. The data of ionospheric stations and the results of total electron content (TEC) measurements at the network of the GPS ground-based receivers and of the GPS receiver onboard the CHAMP satellite were used. Periods of total absorption and blanketing sporadic E layers were observed at high latitudes, whereas durable negative disturbances typical of geomagnetic storms of high intensity were detected at midlatitudes. In the afternoon hours of local time on November 8, 2004, a large-scale ionospheric disturbance of a frontal type was detected on the basis of foF2 and TEC measurements. The disturbance propagated southwestward at a mean velocity of about 200 m/s. The comparison of the relative amplitude of this large-scale disturbance according to the total electron content (～70%) and foF2 (～80%) measurements made it possible to assume a large vertical scale of the disturbance. 相似文献
8.
中国大陆构造环境监测网络(简称陆态网络)是以全球卫星导航定位系统(GNSS)为主,辅以多种空间观测技术,实时动态监测大陆构造环境变化,探求其对资源、环境和灾害的影响的地球科学综合观测网络.基于陆态网络约200个基准站的GPS观测数据,本文探讨了其在电离层空间天气监测与研究方面的应用.包括磁暴期间电离层暴扰动形态,大尺度电离层行进式扰动,太阳耀斑引起的电离层骚扰和低纬电离层不规则体结构等.研究结果表明:陆态网络布局合理,观测数据质量良好,完全可用于中国及周边地区电离层空间天气监测与研究,为进一步开展我国电离层空间天气预警和预报奠定了观测基础. 相似文献
9.
《Journal of Atmospheric and Solar》1999,61(16):1205-1218
The accuracy of single-frequency ocean altimeters benefits from calibration of the total electron content (TEC) of the ionosphere below the satellite. Data from a global network of Global Positioning System (GPS) receivers provides timely, continuous, and globally well-distributed measurements of ionospheric electron content. For several months we have been running a daily automatic Global Ionospheric Map process which inputs global GPS data and climatological ionosphere data into a Kalman filter, and produces global ionospheric TEC maps and ocean altimeter calibration data within 24 h of the end-of-day. Other groups have successfully applied this output to altimeter data from the GFO satellite and in orbit determination for the TOPEX/Poseidon satellite. Daily comparison of the global TEC maps with independent TEC data from the TOPEX altimeter is performed as a check on the calibration whenever the TOPEX data are available. Comparisons of the global TEC maps against TOPEX data will be discussed. Accuracy is best at mid-to-high absolute latitudes (∣latitude∣>30°) due to the better geographic distribution of GPS receivers and the relative simplicity of the ionosphere. Our highly data-driven technique is relatively less accurate at low latitudes and especially during ionospheric storm periods, due to the relative scarcity of GPS receivers and the structure and volatility of the ionosphere. However, it is still significantly more accurate than climatological models. 相似文献
10.
《Journal of Atmospheric and Solar》2008,70(6):879-888
Observations from a network of specially equipped GPS scintillation receivers in Northern Europe are used to investigate the dynamics of ionospheric plasma during the storm events of 30 October and 20 November 2003. The total electron content (TEC) and scintillation data, combined with ionospheric tomography produced by the multi-instrument data analysis system (MIDAS), reveal strong enhancements and steep gradients in TEC during nighttime under a prevailing negative Bz component of the interplanetary magnetic field (IMF). Amplitude and phase scintillation maxima are often co-located with the TEC gradients at the edge of plasma patches, revealing the presence of small-scale irregularities and suggesting association with a tongue of ionization (TOI) convecting in an anti-sunward direction from the American sector across the polar cap. Similarities and differences between the ionospheric response to the two storms are investigated. The 30 October event reveals a quite complex scenario showing two phases of plasma dynamics: the former reflects the expected convection pattern for IMF Bz southward and the latter possibly indicates a sort of TEC plasma stagnation signature of the more complex convection patterns during several positive/negative excursions of IMF Bz. 相似文献
11.
本文利用设在武汉(11436°E,3053°N,磁纬194°)的GPS电离层TEC和电波闪烁监测仪的测量数据,分析了2004年11月强磁暴期间TEC的响应以及电波闪烁和TEC起伏的特征.结果表明,在这次强磁暴期间,武汉及其邻近地区电离层TEC的响应以正暴相为主,正暴相分别出现在两次主相期间,最大正偏离达到50 TECU.这次磁暴另一个重要影响是主相期间L波段振幅闪烁的活动性及其强度显著增强.S4指数最大接近10.伴随增强的闪烁活动,多次观测到深度耗尽的等离子体泡与TEC起伏,TEC变化率的标准差ROTI指数也显著增强.分析揭示, ROTI指数与S4指数呈正相关,相关系数达到097.线性回归计算得到,ROTI和S4的比率为964. 相似文献
12.
Biqiang Zhao Weixing Wan Libo Liu K. Igarashi K. Yumoto Baiqi Ning 《Journal of Atmospheric and Solar》2009,71(1):88-100
This paper presents an investigation of geomagnetic storm effects in the equatorial and middle-low latitude F-region in the West Pacific sector during the intense geomagnetic storm on 13–17 April, 2006. The event, preceded by a minor storm, started at 2130 UT on April 13 while interplanetary magnetic field (IMF) Bz component was ready to turn southward. From 14–17 the ionosphere was characterized by a large scale enhancement in critical frequency, foF2 (4～6 MHz) and total electron content (TEC) (～30TECU, 1TECU=1×1016el/m2) followed by a long-duration negative phase observed through the simultaneous ionospheric sounding measurements from 14 stations and GPS network along the meridian 120°E. A periodic wave structure, known as traveling ionospheric disturbances (TIDs) was observed in the morning sector during the initial phase of the storm which should be associated with the impulsive magnetospheric energy injection to the auroral. In the afternoon and nighttime, the positive phase should be caused by the combination of equatorward winds and disturbed electric fields verified through the equatorial F-layer peak height variation and modeled upward drift of Fejer and Scherliess [1997. Empirical models of storm time equatorial electric fields. Journal of Geophysical Research 102, 24,047–24,056]. It is shown that the large positive storm effect was more pronounced in the Southern Hemisphere during the morning-noon sector on April 15 and negative phase reached to lower magnetic latitudes in the Northern Hemisphere which may be related to the asymmetry of the thermospheric condition during the storm. 相似文献
13.
基于GNSS(Global Navigation Satellite Systems)的发展,我们利用具有北斗、GLONASS和GPS三系统信号接收功能的接收机观测的数据,结合电离层总电子含量(Total Electron Content, TEC)的反演算法,提取出GNSS三系统观测的电离层TEC;同时,将GNSS三系统获取的TEC应用到电离层TEC地图、行进式扰动、不规则体结构和电离层的太阳耀斑响应等方面的研究中,这也是首次使用三种GNSS系统数据对电离层进行联合探测研究.研究结果表明,增加了北斗系统的GNSS三系统在研究中国地区电离层TEC地图、周日变化、逐日变化,行进式扰动以及电离层的实时监测等方面较单系统的GPS具有明显的优势. 相似文献
14.
A detailed analysis of the responses of the equatorial ionosphere to a large number of severe magnetic storms shows the rapid and remarkable collapse of F-region ionisation during post-midnight hours; this is at variance with the presently accepted general behaviour of the low-latitude ionosphere during magnetic storms. This paper discusses such responses as seen in the ionosonde data at Kodaikanal (Geomagn. Lat. 0.6 N). It is also observed that during magnetic storm periods the usual increase seen in the hF at Kodaikanal during sunset hours is considerably suppressed and these periods are also characterised by increased foF2 values. It is suggested that the primary process responsible for these dramatic pre- and post-midnight changes in foF2 during magnetic storms could be due to changes in the magnitude as well as in the direction of usual equatorial electric fields. During the post-midnight periods the change in electric-field direction from westward to eastward for a short period causes an upward E × B plasma drift resulting in increased hF and decreased electron densities in the equatorial region. In addition, it is also suggested that the enhanced storminduced meridional winds in the thermosphere, from the poles towards the equator, may also cause the decreases in electron density seen during post-midnight hours by spatially transporting the F-region ionisation southwards away from Kodaikanal. The paper also includes a discussion on the effects of such decreases in ionisation on low-latitude HF communications. 相似文献
15.
16.
《Journal of Atmospheric and Solar》2008,70(17):2184-2195
This paper examines the night of 23 May 2002 as observed by a large number of Australian ionosondes (19) as well as others situated in New Guinea, Indonesia and China. The arrival of a solar Coronal Mass Ejection (CME) and subsequent negative Bz turnings in the solar wind resulted in a magnetic storm with two bursts of energy inputs into the auroral zones. The energy depositions produced two successive rise and falls in ionospheric height over a 300 km height range within the period 12.30–21.00 UT. The two events were seen in the night-side hemisphere by all ionosondes at Southeast Asian longitudes in the southern hemisphere, as well as in the northern hemisphere. In this paper, the simultaneity and spatial variability of these events is investigated. The first event, after an initial expansion towards the equator, ended with a retreat in the area of height rise back towards the auroral zone. The second event was of greater complexity and did not show such a steady variation in rise and fall times with latitude. Such events are often described as large-scale travelling atmospheric/ionospheric disturbances (LTADs or LTIDs). In the southern hemisphere, the front of the initial height rise was found to move at a speed up to 1300 m/s as was also measured by Tsugawa et al. [2006. Geomagnetic conjugate observations of large-scale travelling ionospheric disturbances using GPS networks in Japan and Australia. Journal of Geophysical Research 111, A02302] from small changes in GPS TEC. The front was uniform across the widest longitudinal range of observation (52° or 5360 km).The relationship between the subsequent fall in ionospheric height and an associated temporary increase in foF2 was found to be consistent with previous observations. Ionospheric drivers that move ionization up and down magnetic field lines are suggested as the common cause of the relationship between foF2 and height. 相似文献
17.
《Journal of Atmospheric and Solar》2008,70(15):1848-1855
Substantial increases of the F2 region peak electron density several hours to a day before the geomagnetic storm onset, the so-called pre-storm enhancements, belong to still not clear and hardly predictable features of the ionospheric disturbances. This paper presents analysis of the pre-storm enhancements observed at middle latitudes for 15 storms out of 65 strong-to-severe geomagnetic storms of the period 1995–2005. All 15 events were accompanied by significant (>20%) increases of foF2 before the storm onset over European area. We focus on the longitudinal extent and height profile of the pre-storm enhancements, particularly on their effects on the F1 and E regions of the ionosphere. Possible origin of such enhancements is also partly discussed. We observe no systematic effect of pre-storm enhancements of foF2 in electron density profiles in the F1 region. The E region (foE) appears to be insensitive to pre-storm enhancements. We find the pre-storm enhancements to be confined to the F2 region. The longitudinal extent of the pre-storm enhancements seems to be 120–240° based on comparison of simultaneous foF2 measurements in Europe, northern USA, and Eastern Asia. 相似文献
18.
2015年3月17日爆发了本太阳活动周最大的地磁暴,Dst指数达到-233 nT.本文利用电离层测高仪f_。F_2和h_mF_2、北斗同步卫星(BDSGEO)TEC以及GPS电离层闪烁S4指数对此次磁暴期间中国中低纬地区(北京、武汉、邵阳和三亚)的电离层变化进行分析,并对此次磁暴所引发电离层暴的可能机制进行了探讨.磁暴期间,中低纬电离层暴整体表现为正相暴之后长时间强的负相暴.3月17日白天中纬正相暴为风场抬升电离层所致,而驼峰区及低纬地区正相暴由东向穿透电场所引起;3月18日白天长时间的强负相暴为西向扰动发电机电场和成分扰动所引起;3月17和18日夜间的负相暴可能是日落东向电场受到抑制以及赤道向风场对扩散的抑制导致驼峰向赤道压缩所致,同时被抑制的日落东向电场强度不足以触发产生赤道扩展F,导致低纬三亚和邵阳夜间电离层闪烁在磁暴期间受到完全抑制.这是我们首次基于北斗同步卫星TEC组网观测开展的电离层暴研究. 相似文献
19.
V. A. Pilipenko M. Bravo N. V. Romanova O. V. Kozyreva S. N. Samsonov Ya. A. Sakharov 《Izvestiya Physics of the Solid Earth》2018,54(5):721-740
The propagation of perturbation caused by the interplanetary shock wave of March 17, 2015 from the solar wind through the magnetosheath, magnetosphere, and ionosphere down to the Earth’s surface is analyzed. The onboard satellite measurements, global magnetometer network data, and records by the receivers of the global positioning system (GPS) providing the information about the total electron content (TEC) of the ionosphere are used for the analysis. By the example of this event, various aspects of the influence of the interplanetary shock wave on the near-Earth environment and ground-based engineering systems are considered. It is shown which effects of this influence are well described by the existing theoretical models and which ones need additional research. The formation of the fine structure of the magnetic impulse of the storm sudden commencement (SC)—the preliminary impulse (PI) and main impulse (MI)—is considered. The MI and compression of the magnetospheric magnetic field is observed by the GOES and RBSP satellites and on the geomagnetically conjugate stations; however, the PI was only noted on the Earth. The PI was detected in the afternoon sector practically simultaneously (within 1 min) with the shock wave impact on the magnetopause. The wave’s response to the SC includes the strongly decaying resonant oscillations of the magnetic shells and the magnetoacoustic cavity mode. This study supports the possibility of detecting the ionospheric response to the SC by the GPS method. The TEC response to the MI was detected in the auroral latitudes although not on every radio path. The TEC modulation can be associated with the precipitation of superthermal electrons into the lower ionosphere which is undetectable by riometers. The burst in the intensity of the geomagnetically induced currents caused by an interplanetary shock wave turns out to be higher than the currents during the storm’s commencement, although the SC’s amplitude is noticeably lower than the amplitude of the magnetic bay related to the substorm. 相似文献
20.
Tamara L. Gulyaeva 《Acta Geophysica》2007,55(2):253-266
Variations of the upper boundary of the ionosphere (UBI) are investigated based on three sources of information: (i) ionosonde-derived
parameters: critical frequency foF2, propagation factor M3000F2, and sub-peak thickness of the bottomside electron density profile; (ii) total electron content (TEC) observations from signals
of the Global Positioning System (GPS) satellites; (iii) model electron densities of the International Reference Ionosphere
(IRI*) extended towards the plasmasphere. The ionospheric slab thickness is calculated as ratio of TEC to the F2 layer peak electron
density, NmF2, representing a measure of thickness of electron density profile in the bottomside and topside ionosphere eliminating the
plasmaspheric slab thickness of GPS-TEC with the IRI* code. The ratio of slab thickness to the real thickness in the topside ionosphere is deduced making use of a similar ratio
in the bottomside ionosphere with a weight Rw. Model weight Rw is represented as a superposition of the base-functions of local time, geomagnetic latitude, solar and magnetic activity.
The time-space variations of domain of convergence of the ionosphere and plasmasphere differ from an average value of UBI
at ∼1000 km over the earth.
Analysis for quiet monthly average conditions and during the storms (September 2002, October–November 2003, November 2004)
has shown shrinking UBI altitude at daytime to 400 km. The upper ionosphere height is increased by night with an ‘ionospheric
tail’ which expands from 1000 km to more than 2000 km over the earth under quiet and disturbed space weather. These effects
are interposed on a trend of increasing UBI height with solar activity when both the critical frequency foF2 and the peak height hmF2 are growing during the solar cycle. 相似文献