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1.
日食电离层效应   总被引：7，自引：4，他引：7       下载免费PDF全文
本文分析了1987年9月23日日环食期间,我国14个电离层站和1988年3月18日日全食期间两个站的垂测仪和偏振仪记录,并综合50年代以来历次日食电离层效应的观测结果,证实:1.E层和F1层光食效应明显,F2层动力学效应显著;2.f0F2存在日食日值大于、小于或等于控制日值三种典型情况;3.TEC食变曲线有凹陷和不凹陷两种典型情况,甚至出现日食日值大于控制日值的异常现象. 本文对F2层和外电离层的动力学特征作了定性讨论,认为:空间等离子体温度急剧下降和沿场扩散是F2层和外电离层日食效应的最主要因素;而磁赤道上空等离子体的沿场扩散、“喷泉”效应,热层风和全（环）食带方位是影响位于磁赤道异常区各电离层站日食电离层效应的主要因素.  相似文献   

2.
The calculation results of parameters of thermal and dynamical processes in the near-Earth plasma during the partial solar eclipse of August 1, 2008, over Kharkov are presented. The calculations showed that during the eclipse there occurred a decrease in the neutral temperature by approximately 17–40 K within the height range 250–350 km, respectively. At heights of 210–580 km, the eclipse resulted in an increase in the density, total plasma flux, and the flux of particles by tens of percentage points due to ambipolar diffusion. The paper presents the results of a comparative analysis of the effects in the ionospheric plasma during the partial eclipses over Kharkov of August 11, 1999; May 31, 2003; October 3, 2005; March 29, 2006; and August 1, 2008. General regularities in eclipse effects are noted.  相似文献   

3.
Introduction Study and observation of solar eclipse geomagnetic effects in China begun in 1936, and since then the total eclipse and total-annular eclipse occurred in Chongan of Fujian Province in 1941j, 1958, 1968, 1980, 1987, 1997 in succession. For these events, modern geomagnetic observations have been made with sufficient preparation. Plentiful solar eclipse data of geomagnetic field variation and research results have been obtained (ZHANG, et al, 1983, LIU, et al, 1986, YANG, DU, …  相似文献   

4.
一次日食电离层效应模拟研究   总被引：3，自引：1，他引：2       下载免费PDF全文
用120°E经度链附近台站电离层垂测资料和一个二维低纬电离层理论模式探讨1995年10月24日日食电离层效应．在日食条件下只考虑日食区计算太阳EUV辐射减少．模式结果显示：（1）日食期间较低高度电离层光食效应显著,电子浓度跟随食分迅速变化,在食甚后浓度减少达到最大。较高高度电离层对日食响应延迟.（2）低纬地区日食日f0.F2比控制日低,而hmF2比控制日高．在低纬度地区日食带来的影响相对较大·（3）赤道附近hmF2食甚后有一突变,出现日食F1.5层。（4）食甚后海口纬度附近F层受日食影响持久,而f0F2在赤道附近出现第2次下降．最后对低纬日食电离层效应的动力学因素进行了初步的讨论．  相似文献   

5.
2009年7月22日上午发生的日全食是21世纪持续时间最长的日全食,其全食带覆盖了中国中部的K江流域,为研究日全食对电离层的影响提供了一次难得的机会,为此本文通过卡尔曼滤波算法实现了实时求解TEC和GPS系统硬件延迟,为实时监测日全食期间电离层变化提供了绝对的电离层TEC.采用上海和浙江区域内GPS网的观测数据,建立了...  相似文献   

6.
2009年7月22日发生在亚太地区的日全食,从北半球中纬地区一直延伸到南半球中纬地区.这次日食期间发生的磁暴和日食时间同步,使得电离层变化较为复杂.为了分析日食期间电离层扰动及其对定位的影响,所采用的GPS数据来源于日全食带内的重庆CORS网(4个站)、武汉CORS网(8个站)数据、IGS站WUHN、SHAO的数据,以及日偏食区域内不同纬度处的若干IGS站.通过比较日食前后连续三天的各个地方TEC变化,以及利用高采样率的CORS网数据研究日食期间TEC的瞬时变化,根据位置和时间的不同,各地日食期间TEC下降约(1~4)TECU.但是,磁暴期间TEC的响应整体表现为正相暴,偏离值达50%以上,且和日食食甚后的TEC变化相重合.同时,求解了日食期间伪距单点定位的实时精度和CORS网内中短基线的实时精度,伪距单点定位的平面精度变化不显著,高程精度下降达数十米,日食初期CORS网中基线的平面精度仍在厘米级内,高程精度仍在分米级内,但是,日食后期发生的磁暴导致基线的平面精度下降到分米级,高程精度下降到米级.  相似文献   

7.
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8.
The observation results of the effects in the geospace plasma during a partially (magnitude ～0.42) solar eclipse are presented. The experimental data were obtained with an incoherent scatter radar of the Institute of the Ionosphere (near Kharkov). During the eclipse, the density at the F2 layer maximum decreased by 32%, the foF2 critical frequency decreased by 17.5%, and the altitude of the F2 layer maximum increased insignificantly. At altitudes of 290–680 km, the electron density decreased by ～25%. During the eclipse, the electron and ion temperature decreased by 70–180 and 0–140 K, respectively, at altitudes of 190–490 km. Near the eclipse main phase, the plasma velocity vertical component decreased by 10–45 m/s at altitudes of 200–470 km, respectively. At the time of the eclipse main phase, the hydrogen ion fractional density increased by 50% as compared to the reference day at altitudes of 450–650 km.  相似文献   

9.
The presence and persistence of an 18-day quasi-periodic oscillation in the ionospheric electron density variations were studied. The data of lower ionosphere (radio-wave absorption at equivalent frequency near 1 MHz), middle and upper ionosphere (critical frequencies f0E and f0F2) for the period 1970–1990 have been used in the analysis. Also, solar and geomagnetic activity data (the sunspot numbers Rz and solar radio flux F10.7 cm, and aN index respectively) were used to compare the time variations of the ionospheric with the solar and geomagnetic activity data. Periodogram, complex demodulation, auto- and cross-correlation analysis have been used. It was found that 18-day quasi-periodic oscillation exists and persists in the temporal variations of the ionospheric parameters under study with high level of correlation and mean period of 18–19 days. The time variation of the amplitude of the 18-day quasi-periodic oscillation in the ionosphere seems to be modulated by the long-term solar cycle variations. Such oscillations exist in some solar and geomagnetic parameters and in the planetary wave activity of the middle atmosphere. The high similarities in the amplitude modulation, long-term amplitude variation, period range between the oscillation of investigated parameters and the global activity of oscillation suggests a possible solar influence on the 18-day quasi-periodic oscillation in the ionosphere.  相似文献   

10.
The CRISTA/MAHRSI experiment on board a space shuttle was accompanied by a broad campaign of rocket, balloon and ground-based measurements. Supporting lower ionospheric ground-based measurements were run in Europe and Eastern Asia between 1 October–30 November, 1994. Results of comparisons with long ionospheric data series together with short-term comparisons inside the interval October-November, 1994, showed that the upper middle atmosphere (h =80–100 km) at middle latitudes of the Northern Hemisphere in the interval of the CRISTA/MAHRSI experiment (4–12 November, 1994) was very close to its expected climatological state. In other words, the average results of the experiment can be used as climatological data, at least for the given area/altitudes. The role of solar/geomagnetic and “meteorological” control of the lower ionosphere is investigated and compared with the results of MAP/WINE, MAC/SINE and DYANA campaigns. The effects of both solar/geomagnetic and global meteorological factors on the lower ionosphere are found to be weak during autumn 1994 compared to those in MAP/WINE and DYANA winters, and they are even slightly weaker than those in MAP/SINE summer. The comparison of the four campaigns suggests the following overall pattern: in winter the lower ionosphere at northern middle latitudes appears to be fairly well “meteorologically” controlled with a very weak solar influence. In summer, solar influence is somewhat stronger and dominates the weak “meteorological” influence, but the overall solar/meteorological control is weaker than in winter. In autumn we find the weakest overall solar/meteorological control, local effects evidently dominate.  相似文献   

11.
The results of observations of the solar eclipse ionospheric effects on March 29, 2006, are presented. The observations were conducted using the partial reflection method near Nizhni Novgorod and the vertical sounding method at the automatic ionospheric station near Murmansk. It has been obtained that the electron density at altitudes of 77 and 91 km decreases by a factor of more than 4; in this case the response of the ionosphere at an altitude of 91 km lags behind the eclipse maximum phase on the Earth by approximately 20 min. It has been established that the eclipse in the E and F1 regions of the polar ionosphere causes a change in the electron density by 15–20%. The delay time of this effect varies from 12 to 24 min depending on the altitude. It has been registered that the reflection virtual altitude at altitudes of the ionospheric F region increases in Murmansk and Nizhni Novgorod.  相似文献   

12.
巴布亚新几内亚日全食的地磁场效应   总被引：1，自引：0，他引：1  
为了研究1983年6月11日日全食的地磁场效应,我们在巴布亚新几内亚的莫尔兹比港（Port Moresby）进行了地磁观测。经过资料分析,在消除当天的正常日变化和干扰变化后,日食效应比较明显,水平强度减小（-3.6±1.2nT）,磁偏角偏东（0.6′±0.1′E）和垂直强度增加（5.0±1.1nT）。证实了日全食引起地磁场强度和方向的变化,与食分、食甚持续时间、太阳高度角（即日食发生的地方时）和季节有关。  相似文献   

13.
During the total solar eclipse on July 22, 2009 in Wuhan, the joint observation test of Na layer and ionosphere was conducted by using the daytime observation atmospheric lidar and the GPS ionosphere detector. The results show that the full width at half maximum (FWHM) of Na layer density slightly narrowed during the total solar eclipse and broadened after the eclipse, while the height of Na peak slightly decreased in the eclipse and increased after the eclipse. These implying that Na layer changes reflect the rapid process of sunrise and sunset. The ionosphere total electron content (TEC) and the sky background light noise also presented an obvious fluctuation characteristic with the changes of solar irradiation during the process of total solar eclipse. The difference lies in that the changes of FWHM of Na layer atoms are much slower than that of ionosphere, the reason for this might be that the Na layer, after being disturbed by the total solar eclipse, will generate a series of complicated photochemical reactions and momentum transport processes, and then recombine the Na atoms. The Na atoms to be detected by the lidar need a lag process, which rightly conforms to the theoretical simulated results.  相似文献   

14.
日偏食对低纬地磁场的影响   总被引：1，自引：0，他引：1  
１９９５年１０月２４日日偏食期间，我们在海南省琼中进行了地磁场总强度的观测和分析，同时运用该地磁台三分量磁照图，分析了地磁Ｄ场Ｄ、Ｈ、Ｚ三分量在日偏食期间的变化特征。结果表明：日偏食期间，磁偏角初亏后逐渐偏东，食甚后偏西；水平强度和总强度初亏后逐渐变小，食甚后上升；垂直强度初亏后逐渐变大，食甚后约１个小时变小。  相似文献   

15.
We performed a comparative study of geomagnetic variations, which are associated with sudden ionospheric disturbances (SIDs) caused by great X-class solar flares on July 14, 2000 (Bastille flare) and on October 28, 2003 (Halloween flare). Intense fluxes of solar X-rays and EUV radiation as well as solar energetic particles (SEP) were considered as sources of abundant ionization of the ionosphere and upper atmosphere. Flare-initiated SIDs are revealed as transient geomagnetic variations, which are generated by enhanced electric currents flowing mainly in the bottom-side ionosphere. Those so-called solar flare effects (SFEs) were studied by using of geomagnetic data from INTERMAGNET worldwide network of ground-based magnetometers. In subsolar region the SFE is mainly controlled by the flare X-rays and/or EUV radiation. We found that in the Halloween flare the contribution of X-rays was comparable with the EUV, but in the Bastille flare the EUV flux was dominant. The ionization at high latitudes is generated by the SEP, which energy flux is comparable and even exceeds the solar electromagnetic radiation in that region. It was shown that in the Halloween event the pattern of SFE is formed by a two-vortex current system, which is similar to the quiet day Sq current system. However, during the Bastille flare, the pattern of induced currents is quite different: the northern vortex shifts westward and southern vortex shifts eastward such that the electroject is substantially tilted relative to the geomagnetic equator. From numerical estimations we found that at middle latitudes the SEP-initiated geomagnetic effect becomes comparable with the effects of solar electromagnetic radiation. It was also shown that the SEP contribute to the SFE in the nightside hemisphere. The revealed features of the SEP impact to the ionosphere were found in a good agreement with the theory of energetic particle penetration to the bottom-side magnetosphere.  相似文献   

16.
The results of the works performed in the field of the most actual problems of physics and optics of the solar-terrestrial coupling have been analyzed. This is the problem of energy in the ionospheric physics, considered because space monitoring of the solar irradiance ionizing the upper ionosphere is still absent. These are the problems of transformation of the solar flare energy and corpuscular precipitation into the microwave ionospheric radiation. Finally, this is the main problem of present-day natural science: the physical mechanism of the solar-terrestrial coupling as applied to the explanation of the detected correlations in the Sun-weather and the Sun-biosphere systems. A unified physical (radio-optical) mechanism for controlling the processes in the lower atmosphere and biosphere (including human being), dependent on the level of solar and geomagnetic activity and related to the ionospheric microwave radiation in transitions between the optically highly excited (Rydberg) states of all components of the upper atmosphere, has been considered.  相似文献   

17.
This paper attempts to reveal whether long-term trends in the ionosphere are reflected in the amplitude range of the geomagnetic daily variation recorded at ground level. The smooth and regular variation observed in the magnetograms on magnetically quiet days is induced by the ionospheric currents flowing in the dynamo region. So it is likely that trends in the conductivity or in the dynamics of this region could produce changes in the current densities, and consequently in the range of the geomagnetic variation. The crucial aspect is how to separate the changes produced by the geomagnetic activity itself, or by secular changes of the Earth's magnetic field, from the part of the variation produced by factors affecting trends in the ionosphere, which could have an anthropogenic origin. To investigate this, we synthesized for several geomagnetic observatories the daily ranges of the geomagnetic field components with a comprehensive model of the quiet-time, near-Earth magnetic field, and finally we removed the synthetic values from the observed ranges at those observatories. This comprehensive model accounts for contributions from Earth's core, lithosphere, ionosphere, magnetosphere and coupling currents, and, additionally, accounts for influences of main field and solar activity variations on the ionosphere. Therefore, any trend remaining in the residuals, assuming that all the contributions mentioned above are properly described and thus removed by the comprehensive model, should reflect the influence of other sources. Results, based on series of magnetic data from observatories worldwide distributed, are presented. Trends in the X and Z components are misleading, since the current system changes in form as well as in intensity, producing changes of the focus latitude in the course of a solar cycle and from one cycle to another. Some differences exist between the long-term trends in the Y component between the real and modelled ranges, suggesting that other non-direct solar causes to the amplitude changes of the solar quiet geomagnetic variation should not be ruled out. Nevertheless, the results also reflect some short-comings in the way that the comprehensive modelling accounts for the influence of the solar activity on the range of the daily geomagnetic variation.  相似文献   

18.
A possible mechanism of earthquake triggering by ionizing radiation of solar flares is considered. A theoretical model and results of numerical calculations of disturbance of electric field, electric current, and heat release in lithosphere associated with variation of ionosphere conductivity caused by absorption of ionizing radiation of solar flares are presented. A generation of geomagnetic field disturbances in a range of seconds/tens of seconds is possible as a result of large-scale perturbation of a conductivity of the bottom part of ionosphere in horizontal direction in the presence of external electric field. Amplitude-time characteristics of the geomagnetic disturbance depend upon a perturbation of integral conductivity of ionosphere. Depending on relation between integral Hall and Pedersen conductivities of disturbed ionosphere the oscillating and aperiodic modes of magnetic disturbances may be observed. For strong perturbations of the ionosphere conductivities amplitude of pulsations may obtain ~102 nT. In this case the amplitude of horizontal component of electric field on the Earth surface obtains 0.01 mV/m, electric current density in lithosphere –10–6 A/m2, and the power density of heat release produced by the generated current is 10–7 W/m3. It is shown that the absorption of ionizing radiation of solar flares can result in variations of a density of telluric currents in seismogenic faults comparable with a current density generated in the Earth crust by artificial pulsed power systems (geophysical MHD generator " Pamir-2” and electric pulsed facility " ERGU-600”), which provide regional earthquake triggering and spatiotemporal variation of seismic activity. Therefore, triggering of seismic events is possible not only by man-made pulsed power sources but also by the solar flares. The obtained results may be a physical basis for a novel approach to solve the problem of short-term earthquake prediction based on electromagnetic triggering phenomena.  相似文献   

19.
本文介绍了1980年2月16日日全食时,在云南鹤庆县（100°12′E,26°35′N）,测量日本ETS-Ⅱ同步卫星136MHz信标法拉弟旋转所得到的一些主要观测结果:（1）电子总含量的日变曲线中出现提前日落现象;（2）F区峰下电离对法拉弟旋转的贡献在日食期间相对变小;（3）没有出现与日食明显有关的声重波扰动。  相似文献   

20.
The observations of the geomagnetic field variations in the range of periods 1–1000 s, which accompanied the launches of 65 Soyuz and Proton rockets from the Baikonur site in 2002–2006, have been analyzed. The measurements were performed near Kharkov (the distance from the launching site is R ≈ 2100 km). Three groups of disturbances, with delays of 6–7, 30–70, and 70–130 min dependent on the time of day, have been revealed. The disturbance duration was 10–30, 50–70, and 45–70 min, respectively. Periods of 3–6, 6–12, and 6–12 min, respectively, predominated in the geomagnetic pulsations. The amplitudes of these pulsations reached 3–6 nT. The physical model of the observed geomagnetic disturbances, which generally agrees with the measurements, has been proposed.  相似文献   

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