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1.
地磁暴发生时,电离层会有偏离平均水平的强烈扰动.基于全球电离层TEC及其时间变化率ROTI(Rate of TEC Index)数据,对2014年8月一次中等强度磁暴期间的全球电离层影响进行了分析,探讨了磁暴所引发电离层暴的可能机制.研究发现,本次磁暴伴随有明显的电离层暴效应.磁暴期间:南半球电离层以正相暴为主,北半球电离层暴则整体表现为短暂正相暴后长时间强的负相暴;电离层在北半球的下降比南半球强,并且这种下降持续了约一周时间;低纬区域电离层变化幅度明显小于中纬区域,高纬区域则主要表现为负暴效应;赤道北驼峰出现了明显的南移现象,直至磁赤道两侧双驼峰结构消失.对磁暴期间三个不同扇区的电离层ROTI变化的分析表明:欧洲-非洲扇区磁暴前有电离层闪烁发生,磁暴发生后消失,而东亚-澳大利亚及美洲扇区则无此现象出现.研究结果表明,此次磁暴期间的电离层变化存在明显的时间和空间差异. 相似文献
2.
地磁暴发生时,电离层会有偏离平均水平的强烈扰动.基于全球电离层TEC及其时间变化率ROTI(Rate of TEC Index)数据,对2014年8月一次中等强度磁暴期间的全球电离层影响进行了分析,探讨了磁暴所引发电离层暴的可能机制.研究发现,本次磁暴伴随有明显的电离层暴效应.磁暴期间:南半球电离层以正相暴为主,北半球电离层暴则整体表现为短暂正相暴后长时间强的负相暴;电离层在北半球的下降比南半球强,并且这种下降持续了约一周时间;低纬区域电离层变化幅度明显小于中纬区域,高纬区域则主要表现为负暴效应;赤道北驼峰出现了明显的南移现象,直至磁赤道两侧双驼峰结构消失.对磁暴期间三个不同扇区的电离层ROTI变化的分析表明:欧洲-非洲扇区磁暴前有电离层闪烁发生,磁暴发生后消失,而东亚-澳大利亚及美洲扇区则无此现象出现.研究结果表明,此次磁暴期间的电离层变化存在明显的时间和空间差异. 相似文献
3.
利用人工神经网络提前1h预报电离层TEC 总被引:1,自引:1,他引:0
提出了一种利用人工神经网络提前1h预报电离层TEC的简便方法. 考虑到实际工程应用要求, 没有使用其他空间天气参数, 而是选择电离层TEC观测数据本身作为输入参数. 输入参数为当前时刻TEC、一阶差分、相对差分和时间, 输出参数为预报时刻TEC. 利用文中介绍的GPS/TEC处理方法解算厦门站2004年电离层TEC观测数据, 对预报方法进行评估, 全年平均相对误差为9.3744%, 预报结果与观测值相关性达到了0.96678. 结果表明, 利用人工神经网络方法提前1h预报电离层TEC有很好的应用前景. 相似文献
4.
利用全球分布的GPS原始观测数据提取的电离层总电子含量(TEC)分析了2004年11月6日至12日期间全球电离层暴的形态特点与发展过程.结果表明,11月8日磁暴主相期间电离层暴以大范围的强烈正暴为主,在11月10日的恢复相,Dst又一次降到最低值前后期间,电离层再次受到很强的扰动,大范围的正暴和负暴交替出现.这次磁暴期间夏季半球的负暴更加强烈,反映出负暴偏向于在夏季半球发生的季节变化特点.另外,磁暴期间,夜晚TEC值普遍比磁暴前的平静期要低,具体是什么机制导致还需要进一步收集数据和分析. 相似文献
5.
利用MF雷达对耀斑期间电离层D区电子密度的观测研究 总被引:1,自引:0,他引:1
利用MF雷达观测资料对X级别耀斑爆发期间在66—80 km高度之间的电子密度进行了研究,观测到了耀斑爆发期间电子密度的突然增加,在较低高度上的电子密度的时间变化趋势与耀斑的软X射线辐射通量相关.电子密度的变化强度依赖于具体的耀斑参数,有些耀斑引起的电子密度增加高达400 cm-3,有些仅为100 cm-3左右.但耀斑期间在这一高度区间增加的总电子含量增量仅占耀斑辐射引起的整个电离层总电子含量增量的千分之一左右.最后,利用恢复阶段电子密度的时间变化过程估算了1997年11月4日耀斑期间部分高度上的有效复合系数. 相似文献
6.
从微分多普勒观测数据确定电离层总电子含量 总被引:1,自引:1,他引:0
本文提供一种对微分多普勒观测数据进行处理的方法, 从而得到有关电离层总电子含量的信息, 为研究电离层特性提供有用资料. 相似文献
7.
重点报道了一种TEC伪距观测量的夜间抖动异常现象,分析了这种现象的观测特征,指出了夜间GPS伪距观测量的异常抖动,特别足日落后时段GPS伪距观测量的散开十分严重的现象不是个别的偶然现象.在考察了周围环境之后初步排除了这种现象是由周围地物引起的可能性,而进一步与电离层不均匀体(spread-F)的特征,特别是它发生率最大的地方时进行比较,认为这是一种电离层效应,由大尺度的电离层不规则结构造成的散射很可能是这种夜间散开的主要原因.木文仪就单站GPS观测资料认证了这种夜间强烈抖动的存在,分析了北京上空电离层中发生的不均匀体或各种扰动对GPS信号的可能影响及其观测特征,指出了夜间GPS伪距观测量的异常抖动,特别是日落后时段GPS伪距观测量的散开十分严重的现象,可以用于电离层不规则结构的研究.由于GPS没备比较简便、数据量大、精度高、适用于各种环境等特点,我们发展的单站GPS数据分析方法可能会对研究电离层TEC夜问涨落异常增加现象,包括地域、时间上的统计特性比较有利. 相似文献
8.
电离层总电子含量(TEC)是研究空间天气特性的重要参量,通过分析电离层TEC,可以了解空间环境的变化特征.利用IGS提供的1999—2016年全球电离层TEC格网数据,按照地磁纬度将全球划分为高、中、中低、低磁纬四个区域,计算不同区域的电离层扰动;利用大量统计数据选取电离层扰动事件的判定阈值,分析电离层扰动与太阳活动、时空之间的关系;计算电离层扰动指数与地磁活动之间的相关系数.结果显示:电离层扰动与太阳活动变化具有较强的正相关特性.在太阳活动低年,电离层扰动事件发生的概率约为1.79%,在太阳活动高年发生扰动的概率约为10.18%.在空间分布上,无论是太阳活动高年还是低年,高磁纬地区发生扰动事件的概率均大于其他磁纬出现扰动事件的概率.计算得到的中磁纬和中低磁纬地区电离层扰动指数与全球地磁指数Ap的相关系数分别为0.57和0.56,说明电离层扰动指数与Ap具有较好的相关关系;高磁纬电离层扰动指数与Ap的相关系数为0.44;低磁纬扰动指数与Ap的相关系数为0.39.以上结果表明,不同区域电离层扰动与全球地磁指数Ap的相关性不同,测定区域地磁指数可能会提高与电离层扰动的相关性. 相似文献
9.
利用IGS提供的双频GNSS观测数据,分析了Kalman方法解算电离层垂直总电子含量(Vertical Total Electron Content,VTEC)存在的问题,提出了Kriging-Kalman改进解算方法,并对两种方法解算的电离层VTEC进行分析和比较.结果表明:在低纬地区,当观测卫星数量发生改变时,Kalman方法解算的VTEC存在跳变异常,Kriging-Kalman方法解算的VTEC变化较为平稳,不存在跳变现象.对比分析耀斑期间两种方法解算VTEC的变化,发现Kalman方法解算的VTEC变化明显小于耀斑引起VTEC的增量;Kriging-Kalman方法解算结果与实际变化相一致.表明Kriging-Kalman方法计算精度更高,能够更精确计算耀斑等剧烈异常空间天气活动期间的VTEC及其变化,有利于电离层VTEC日常精确监测、研究和工程应用. 相似文献
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利用MSIS模型和背景太阳辐射谱模型,在一定大耀斑辐射谱假设的前提下,计算了耀斑期间日照边缘区域的电子产生率,分析了这一区域电离层电子密度的变化特点.结果表明,大耀斑期间在日照边缘区域,甚至大于太阳天顶角90°的区域都有明显的电子产生率的增加.从不同太阳天顶角处的电子产生率剖面的形态来看,随着天顶角的增加最大电离率减少,但高度增加.计算还显示了在太阳天顶角小于90°的区域内电子产生率的垂直分布有明显的双峰结构,这种结构对应着电离层的E区和F区,但在天顶角大于90°区域,F区的电子产生率要大得多.考虑到离子和电子的复合过程,这一区域的总电子含量的增加主要产生在高F区. 相似文献
11.
论述了应用色散多普勒技术,在求解测站上空大面积TEC的方法中,卫星相对测站径向速度变化对电离层产生的微分多普勒频移的影响,找到了比较好的修正方法,并对若干测量计算结果进行了由定性到定量分析,绘出了测站上空任一点TEC的日变化曲线。 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(1):16-28
We present the results of study on the variations of ionospheric total electron content (TEC) by using global, hemispheric, and regional electron contents computed from the global ionospheric maps (GIMs) for the period from 1999 to 2020. For a low and moderate solar activity, the global and regional electron contents vary linearly with solar 10.7 cm radio flux and EUV flux. While a saturation effect in the electron content verses EUV and F10.7 is found during the high solar activity periods at all regions, the maximum effect is observed at low-latitudes followed by high and mid-latitudes region. The extent of saturation effect is more pronounced for F10.7 as compared to EUV. A wavelet transform is applied to global and hemispheric electron contents to examine the relative strength of different variations. The semi-annual variations dominate in the northern hemisphere, whereas annual variations dominate in the southern counterpart. The amplitude of annual variations in southern hemisphere is found to be higher than northern counterpart at all latitudes. This asymmetry in the amplitude of annual variation is maximum at low-latitudes, followed by mid and high-latitudes, respectively. The semi-annual variations are in-phase in both hemisphere and follow the solar cycle. The northern hemisphere depicts relatively large amplitude of semi-annual variations and exhibit the maximum effect at high-latitudes. 相似文献
14.
A. Krankowski I.I. Shagimuratov L.W. Baran G.A. Yakimova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(4):628-638
GPS observations from EUREF permanent GPS network were used to observe the response of TEC (Total Electron Content) to the total solar eclipse on October 3, 2005, under quiet geomagnetic conditions of the daytime ionosphere. The effect of the eclipse was detected in diurnal variations and more distinctly in the variations of TEC along individual satellite passes. The trough-like variations with a gradual decrease and followed by an increase of TEC at the time of the eclipse were observed over a large region. The depression of TEC amounted to 3–4 TECU. The maximum depression was observed over all stations located at the maximum path of the solar eclipse. The delay of a minimum level of TEC with respect to the maximum phase of the eclipse was about 20–30 min. 相似文献
15.
Yanhong Chen Guanyi MaWengeng Huang Hua ShenJinghua Li 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(4):617-623
This paper presents small scale (duration ?1 h, ΔTEC ? 1TECU) night-time total electron content (TEC) enhancements observed at the equatorial anomaly region in China, for the first time. The data is from a GPS receiver chain established in 2005 by Institute of Center for Space Science and Applied Research, Chinese Academy of Sciences and a GPS receiver of International GPS Service (IGS), located between Fuzhou (26.1°N, 119.3°E) and Nanning (22.8°N, 108.3°E). Two other GPS observations of IGS taken at higher latitude were also used to investigate the localization of such phenomenon. The characteristics of the night-time TEC enhancement are examined with two case studies. The TEC increases about 1–3TECU, intermittently. While the night-time TEC enhancement mainly occurs at the equatorial anomaly region, it can be observed at middle latitude as well. The spatial size of the enhancement region is less than 5° in longitude. The primary statistical study shows that the TEC enhancement is more often observed in spring and autumn, but rarely in summer. It has no dependence on geomagnetic activity. The enhancement can occur both before and after midnight. 相似文献
16.
Chin-Chun Wu K. Liou Shao-Ju Shan C.-L. Tseng 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(4):611-616
The ionospheric total electron content (TEC) in the northern hemispheric equatorial ionospheric anomaly (EIA) region is studied by analyzing dual-frequency signals of the Global Position System (GPS) acquired from a chain of nine observational sites clustered around Taiwan (21.9–26.2°N, 118.4–112.6°E). In this study, we present results from a statistical study of seasonal and geomagnetic effects on the EIA during solar cycle 23: 1994–2003. It is found that TEC at equatorial anomaly crests yield their maximum values during the vernal and autumnal months and their minimum values during the summer (except 1998). Using monthly averaged Ic (magnitude of TEC at the northern anomaly crest), semi-annual variations is seen clearly with two maxima occurring in both spring and autumn. In addition, Ic is found to be greater in winter than in summer. Statistically monthly values of Ic were poorly correlated with the monthly Dst index (r = −0.22) but were well correlated with the solar emission F10.7 index (r = 0.87) for the entire database for the period during 1994–2003. In contrast, monthly values of Ic were correlated better with Dst (r ? 0.72) than with F10.7 (r ? 0.56) in every year during the low solar activity period (1994–1997). It suggests that the effect of solar activity on Ic is a longer term (years), whereas the effect of geomagnetic activity on Ic is a shorter term (months). 相似文献
17.
新乡上空电离层总电子含量的经验模式 总被引:2,自引:2,他引:2
基于电离层总电子含量与太阳活动性之间的线性相关关系,利用在新乡长期测量所得的电离层总电子含量的资料,得出了总电子含量的一种经验模式。 相似文献
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典型电离层多普勒记录及其讨论 总被引:7,自引:1,他引:7
由于地面电离层多普勒频率偏移测量具有时间连续、设备相对简便等固有特征,它特别适合于扰动监测.本文在整理北京大学电离层高频多普勒台站观测资料的基础上,给出了一些典型电离层多普勒效应观测现象,这些现象反映了多普勒频移对电离层Es,声重波,不规则结构及耀斑引起的突然扰动等的响应,表明多普勒资料的细致分析对电离层形态学研究有其特殊意义.利用IRI模型,对多普勒频移的太阳耀斑效应及电离层不规则结构对多普勒频移的影响进行了模拟计算,理论结果与观测基本一致,从而大体上解释了这些响应的物理机制.论文最后对观测到的一种特殊的记录类型——S型描迹的具体成因作了详细的分析和讨论,指出在一定条件下,以一定相位速度水平传播的声重波可以产生这类记录,给出了相位速度和振幅等声重波参数与记录描迹形状的关系,这对从多普勒频移记录推演电离层中的波动特征有一定的帮助. 相似文献
20.
Tong Xu Zhi Chen Chunbin Li Jian Wu Yanli Hu Zhensen Wu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The present paper describes the variations of the GPS total electron content (TEC) from the International GNSS service network and surface latent heat flux (SLHF) from the Scientific Computing Division of the National Center for Atmospheric Research (NCAR) before the 11 March 2011 M9.0 Sendai earthquake, respectively. The analysis shows pronounced enhancements in the GPS TEC and SLHF a few days prior to the earthquake event. The maximum increase in the GPS TEC was about 30 TECu with an extended spatial distribution on a geomagnetically quiet day (Dst ? −20 nT, between two moderate geomagnetic storms), 8 March, 3 days prior to the earthquake. This giant positive disturbance was possibly associated with the impending disastrous earthquake and contributed from the enhanced solar radiation. Moreover, there were several anomalous regions of SLHF on the global map, but an area of enhanced SLHF very close to the epicenter. The purpose of this paper is to report the existence of the changes in surface and ionosphere, and show the potential application of multi-source data to identify seismic precursors. 相似文献