共查询到20条相似文献，搜索用时 46 毫秒
1.
V. A. Ivanova V. I. Kurkin N. M. Polekh L. V. Chistyakova I. G. Brynko V. V. Chuyev Z. F. Dumbrava I. N. Poddelskii 《Geomagnetism and Aeronomy》2011,51(8):1101-1104
The morphological features of wave-like ionospheric disturbances with periods of 1–2 h and the spatial extent exceeding 1000
km are studied. Oblique-incidence sounding data of the ionosphere, obtained in eastern Siberia during several continuous monthly
experiments on three radio paths from 2006 to 2010, have been used. Large-scale traveling ionospheric disturbances generated
during magnetic storms and large-scale wave-like ionospheric disturbances registered during geomagnetically quiet periods
are considered. Small-scale ionospheric structures were also observed against a background of large-scale traveling iono-spheric
disturbances considered in this study. 相似文献
2.
Observations of traveling ionospheric disturbances (TIDs) associated with atmospheric gravity waves (AGWs) generated by the moving solar terminator have been made with the Millstone Hill incoherent scatter radar. Three experiments near 1995 fall equinox measured the AGW/TID velocity and direction of motion. Spectral and cross-correlation analysis of the ionospheric density observations indicates that ST-generated AGWs/TIDs were observed during each experiment, with the more-pronounced effect occurring at sunrise. The strongest oscillations in the ionospheric parameters have periods of 1.5 to 2 hours. The group and phase velocities have been determined and show that the disturbances propagate in the horizontal plane perpendicular to the terminator with the group velocity of 300–400 m s–1 that corresponds to the ST speed at ionospheric heights. The high horizontal group velocity seems to contradict the accepted theory of AGW/TID propagation and indicates a need for additional investigation. 相似文献
3.
D. V. Blagoveshchenskii 《Geomagnetism and Aeronomy》2016,56(4):448-456
We analyze ionospheric oblique sounding data on three high-latitude and one high-latitude–midlatitude HF radio paths for February 15 and 16, 2014, when two substorms and one magnetic storm occurred. We investigate cases of anomalous propagation of signals: their reflection from sporadic layer Es, lateral reflections, type “M” or “N” modes, the presence of traveling ionospheric disturbances, and the diffusivity of signals and triplets. The most significant results are the following. In geomagnetically undisturbed times, sporadic Es-layers with reduced maximum observed frequencies (MOFEs) on three high-latitude paths were observed in both days. The values of MOFEs during disturbances are large, which leads to the screening of other oblique sounding signals reflected from the ionosphere. On all four paths, the most frequently traveling ionospheric disturbances due to the terminator were observed in quiet hours from 03:00 to 15:00 UT on the first day and from 06:00 to 13:00 UT on the second day of the experiment. In addition, both the sunset terminator and the magnetic storm on the high-latitude–mid-latitude path were found to generate traveling ionospheric disturbances jointly. No such phenomenon was found on high-latitude paths. 相似文献
4.
Seismoionospheric disturbances in the parameters of the ionospheric F 2 and sporadic E layers at the chain of the Japanese stations for vertical sounding of the ionosphere before strong crustal earthquakes with M>6.5 during the period from 1968 to 1992 have been considered. The dependence of the disturbance time of appearance in the ionospheric parameters on the earthquake magnitude and epicentral distance, obtained for each specific earthquake using the selected series of ionospheric stations, made it possible to consider these disturbances among medium-term precursors of earthquakes. The velocity of the disturbance front apparent motion has been determined based on the model of horizontal radially-isotropic disturbance propagation from the projection of the impending earthquake epicenter to the ionospheric altitudes. The conclusion has been made that the distinguished seismoionospheric disturbances follow the boundary of the earthquake preparation region, expanding on the Earth’s surface. 相似文献
5.
针对现有单站电离层行波扰动指数(Single Receiver TID Index,SRTI)探测中尺度电离层行波扰动时探测周期范围有限的问题,本文提出了一种改进的SRTI方法,以提高探测扰动周期的适用范围.介绍了利用SRTI和改进的SRTI探测中尺度电离层行波扰动的原理,从理论上分析比较了二者探测扰动周期范围的能力,并采用美国加州南部的5个IGS站2012年年积日189的GPS观测数据,对电离层扰动进行了分析.结果显示在21∶30—23∶00LT时,扰动观测序列存在周期为15min和39min的扰动波,但是现有SRTI方法只探测到了前者,而改进的SRTI法很好地探测到了两个周期的扰动波,表明其对短周期和较长周期的扰动均具有较好的灵敏性.利用改进的SRTI法计算的扰动观测序列,应用傅里叶变换相位差分法估计了电离层扰动的传播参数,其结果总体上与前人研究成果一致,这表明改进的SRTI法完全可以应用于电离层行波扰动的研究中,而且由于计算简单,在处理大量数据时具有一定优势. 相似文献
6.
用数字测高仪漂移测量研究电离层声重波扰动 总被引：8，自引：1，他引：8
数字测高仪Digisonde中的漂移测量,常用来研究小尺度电离层扰动,如电离层小不均匀体的漂移。文中提出一种新的分析方法,利用漂移测量数据中多普勒频移和到达角参量的最大熵动态功率谱,估算声重波一类大尺度电离层扰动的水平传播速度和传播方向。作为实例,研究了Millstone Hill测高仪站的漂移观测资料,并对处理结果进行了初步分析。分析结果表明,从数字测高仪漂移测量数据中,可有效地提取声重波一类大尺度电离层扰动的传播参量,在电离层动力过程的研究中很有意义。 相似文献
7.
V.I. Kurkin O.M. Pirog N.M. Polekh A.V. Mikhalev I.N. Poddelsky A.E. Stepanov 《Journal of Atmospheric and Solar》2008,70(18):2346-2357
We present the results of studies of the subauroral and mid-latitude ionosphere variations in the north-eastern region of Asia. We used the data from network of vertical and oblique-incidence sounding ionosondes and optical measurements. Long-term experiments on the radio paths Magadan–Irkutsk and Norilsk–Irkutsk were carried out within the period 2005–2007. Vertical sounding stations operated in standard regime. Observation of airglow near Irkutsk was provided by the zenith photometer that measured intensities of 557.7 and 630.0 nm atomic oxygen emissions. The results may be summarized as follows. (1) Large daytime negative disturbances are observed during the main and recovery phases mainly at high latitudes, whereas the positive disturbances observed during the main phase at mid latitudes. The disturbances changed their sign between Yakutsk and Irkutsk. (2) During the main and recovery storm phases the fall of foF2 associated with the equatorward wall of the main ionospheric trough is observed in the afternoon and evening. (3) Fluctuations of the electron density more intensive at mid latitudes during the storm main phase are observed during all considered periods. They are classed as traveling ionospheric disturbances (TID). Such sharp gradients of electron density are responsible for the strong changes in the characteristics of the radio wave propagation, particularity MOF. (4) A large-scale ionospheric disturbance is noted at the meridional chain of ionosonds in December 2006 as the sharp increase of foF2. It appears in the evening in the minimum of Dst at high latitude and propagate to equator. (5) A maximum of 630 nm emission above Irkutsk corresponds to the foF2 increase. (6) The obtained experimental data on the net of vertical and oblique-incidence sounding with high time resolution show that such net is the effective facility to study the conditions of the radio wave propagation and can be used for the diagnostic of the ionosphere. 相似文献
8.
为进一步探索基于多颗卫星观测数据的地震电离层现象识别,利用Swarm星座三颗卫星观测的电子密度数据和磁场数据,对已报道的2017年11月12日伊朗MW7.3地震震前第9天震中附近的一次地震电离层扰动现象进行辨识。通过分析三颗卫星相邻轨道的电离层扰动特征,获得了异常扰动存在的空间范围;利用Swarm星座三颗卫星轨道的时间和空间差异,计算出异常扰动在空间中可能的传播特征;使用同步观测的磁场数据判断其电磁辐射特性。最终根据现有对地震电离层耦合的认知,并结合分析的结果,认为该扰动为非震源发出的声重波扰动,非沿纬向传播的电离层行波扰动,非同步电磁辐射引发扰动,而是与伊朗MW7.3地震孕育活动无关的一次高纬度强烈电离层活动所引起的扰动变化。 相似文献
9.
O. A. Laryunin 《Geomagnetism and Aeronomy》2018,58(2):245-251
The characteristic U-shaped traces (cusps) in ionograms are associated with the passage of traveling ionospheric disturbances (TIDs), which lead to horizontal electron density gradients in the ionosphere and, therefore, to off-angle reflections in radio sounding. A new form of representation is considered for daily ionospheric sounding data. A compound parabolic layer model is proposed, which allows analytical calculation of ray paths to speed up the “homing-in” of the rays. Changes in the shape of the trace in the ionogram due to varying the TID characteristics are examined. A discussion is given of the possibilities for estimating TID characteristics from digitized vertical sounding ionograms. 相似文献
10.
V. I. Kurkin N. M. Polekh O. M. Pirog V. A. Moshkova I. N. Poddel’sky 《Geomagnetism and Aeronomy》2009,49(8):1249-1253
The oblique sounding data at the Magadan-Irkutsk and Norilsk-Irkutsk paths together with the vertical sounding at stations located in northeastern Russia were used to analyze ionospheric disturbances in September 2005 and during geophysically active period in December 2006. It is found that during the main phase of magnetic storms, wave disturbances with a period of 2–4 h are registered. These disturbances cause variations in the layer maximum height up to 40–100 km and in the critical frequency up to 1.5–2 MHz. Those variations change substantially values of the maximum observed frequencies (MOF) of the ionospheric radio channel at the paths considered. Such wave disturbances can be caused by generation of AGWs in the auroral zone and their propagation to equatorial latitudes. 相似文献
11.
本文通过观测实例探讨并论证了电离层高频多普勒观测在扩展-F研究中的应用.实例和相应分析表明:首先,由于高频多普勒记录的时间连续性,有利于从观测角度了解扩展-F的时间演化过程;其次,高频多普勒偏移对不规则结构造成的回波弥散、对不同尺度行进电离层扰动(TID)以及耀斑引起的突然频率偏移(SFD)效应都很敏感,这些现象在记录上出现的时间关系有利于了解扩展-F的触发因素或扩展-F与其他电离层背景扰动之间的联系或相互作用;最后,高频多普勒记录对于持续时间较长(几小时以上)或很短(小于1小时)的扩展-F都能够完整地反映,不会产生因为观测间歇形成的缺失,也可以有效区分究竟是连续一次还是一段时间内断续的扩展-F现象.高频多普勒观测有其自身的优点同时也具有一定的局限性,本文对其局限性诸如缺乏空间分辨率等也做了分析.指出发挥高频多普勒观测的优势,综合应用多种资料,通过不同手段的数据分析和比较,可以更好地为电离层扰动的物理机制和预报研究提供正确的观测依据. 相似文献
12.
O. A. Pokhotelov M. Parrot E. N. Fedorov V. A. Pilipenko V. V. Surkov V. A. Gladychev 《Annales Geophysicae》1995,13(11):1197-1210
A review is presented of the effects influencing the ionosphere which are caused by acoustic emission from different sources (chemical and nuclear explosions, bolides, meteorites, earthquakes, volcanic eruptions, hurricanes, launches of spacecrafts and flights of supersonic jets). A terse statement is given of the basic theoretical principles and simplified theoretical models underlying the physics of propagation of infrasonic pulses and gravity waves in the upper atmosphere. The observations of “quick” response by the ionosphere are pointed out. The problem of magnetic disturbances and magnetohydrodynamic (MHD) wave generation in the ionosphere is investigated. In particular, the supersonic propagation of ionospheric disturbances, and the conversion of the acoustic energy into the so-called gyrotropic waves in the ionospheric E-layer are considered. 相似文献
13.
电离层声重波扰动的高频无线电诊断 总被引：1，自引：1，他引：1
为了充分发挥现代数字式电离层探测仪在电离层结构与优动研究中的潜力,必须在传统的频高图真高换算的基础上,发展新的反演理论和算法.本文介绍了随时空缓变的各向异性电离层介质中无线电波包传播的广义射线方程组,讨论了计算波包射线几何路径以及计算波包参数,如频移、波矢、群时延等沿射线路径变化的传播正问题,并详细讨论了根据波包参量的测定值反演介质结构和扰动伏态的传播反问题.文中若干实验实例表明,这种反演理论和算法可用于数字式电离层探测仪记录的分析,它使高频无线电波探测技术成为研究全球电离层声重波一类扰动的有力工具。 相似文献
14.
Berta Melndez Oliveros Raúl Martín Hernndez Lourdes Palacio Surez 《Journal of Atmospheric and Solar》2005,67(17-18):1706
The meridional propagation velocities of the ionospheric F2-region response to 268 geomagnetic storms are calculated. Ionospheric vertical sounding data of 1 h time resolution from several stations located in a longitude sector approximately centred along the great circle that contains both the geomagnetic poles and the geographic poles are used.Most meridional propagation velocities from high to low latitudes are less than 600 m/s. The smaller velocities are typical of global neutral meridional wind circulation and the larger are representative of traveling atmospheric disturbances.Simultaneous disturbances at several locations are more frequent during positive phases than during negative phases. Negative phase meridional propagation velocities associated with meridional neutral winds are less frequent in the southern hemisphere when compared with corresponding velocities observed in the northern hemisphere. This may be related to the fact that the distance between the geomagnetic pole and the equator is smaller in the northern hemisphere.Most negative phase onsets are within the 06–10 LT interval. For middle geomagnetic latitudes a “forbidden time interval” between 11 and 14 LT is present. The positive phase onsets show the “dusk effect”. 相似文献
15.
A. F. Yakovets V. V. Vodyannikov A. B. Andreev G. I. Gordienko Yu. G. Litvinov 《Geomagnetism and Aeronomy》2011,51(5):640-645
The seasonal dependence of the probability of large-scale traveling ionospheric disturbances is analyzed based on nighttime
ionospheric parameters measured over Almaty during 2000–2007, as well as the dependence of annual average probabilities of
their occurrence on the sunspot cycle. The behavior of these probabilities is compared with magnetic activity. 相似文献
16.
Two methods for diagnosing ionospheric disturbances using VLF signals received on the DEMETER satellite are considered in connection with two cases of high seismic activity: the method for analyzing a signal reception zone in order to find large-scale spatial variations and the residual signal method used to reveal time variations. Based on an analysis of the VLF signal reception zone, performed in connection with the catastrophic earthquake near Sumatra, it has been found out that the signal amplitude decreased during a month before the earthquake. As a result, it has been concluded that the zone of ionospheric disturbances extends for several thousand kilometers. It has been indicated that the residual signal method showed good agreement between the ground and satellite data when high seismic activity near Japan was analyzed. 相似文献
17.
Using three radio techniques for determining the spatial and terminal distribution of the electron concentration in the ionospheric
F region, a number of parameters of medium-scale travelling ionospheric disturbances (the effective thickness of the atmospheric
waveguide and height of its axis, spatial and time periods, propagation speeds, and maximum amplitudes of the disturbances)
are determined. 相似文献
18.
J. MacDougall M.A. Abdu I. Batista P.R. Fagundes Y. Sahai P.T. Jayachandran 《Journal of Atmospheric and Solar》2009,71(17-18):2013-2016
This paper deals with how atmospheric gravity waves produce the traveling ionospheric disturbances (TIDs) that are observed by ionosondes. It is shown that, rather than directly producing variations of ionospheric height, a likely mechanism involves changes in ionization density by gradients in the horizontal atmospheric gravity wave air motion. These density changes can be observed as variations of the height of an ionospheric isodensity surface (the usual way of measuring TIDs). This mechanism involving enhancement/depletion of ionospheric density requires quite moderate atmospheric gravity wave air motion speeds, and works well at almost all latitudes. 相似文献
19.
The possibility of magnetogravity wave (MGW) propagation in the equatorial ionosphere taking into account the finite conductivity is analyzed. The dispersion relation shows the existence of two propagating MGW modes in ionospheric layer F2: high-frequency (HF MGW) and low frequency (LF MGW). The dispersion relations for them are executed and the characteristic frequencies and propagation velocities are determined. In this part of research the spectral features of disturbances in components of environment displacement for HF MGW, generated by a mass source, is carried out. The results are applied to estimate the values of density, pressure and magnetic field spectral components of magnetogravity disturbances caused by horizontal meteor sweep. They may be useful in the analysis of ionospheric disturbances excited by high energy geophysical sources. 相似文献
20.