共查询到18条相似文献,搜索用时 718 毫秒
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2000年4月6-7日的大磁暴(Dst最小值达到-317nT),急始(SSC)在6日1640UT左右出现,随后磁暴主相开始,约在7日0013UT进入恢复相.磁暴主相前期武汉地区F区电离层出现突然抬高现象,在2h内h′F和hmF2分别较暴前日增加约200km.此期间台湾中沥也几乎同时出现了F区电离层突增现象.磁暴主相前期f0F2较暴前日下降1.6MHz,其变化幅度在f0F2逐日变化起伏范围内,但7日f0F2最大值明显低于4-6日暴前水平,并伴随着波动特征.认为此次磁暴主相前期武汉地区F区电离层突增现象,可能和夜间磁暴常出现的扰动东向电场有关. 相似文献
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中国典型区域Es特性研究 总被引:3,自引:1,他引:2
利用中国海口、长春和拉萨三个站1976-1986年一个太阳周的观测数据, 对中国典型区域的Es特性进行了研究. 分析了不同强度Es (f0Es > 3, 5, 7, 9MHz)出现概率随本地时、季节以及太阳活动的变化规律, 并对电离层Es遮蔽情况(包括全遮蔽和半遮蔽)进行了系统分析. 研究结果表明, 各种强度的Es出现概率均是白天大于夜间, 夏季高于其他季节, 随太阳活动性变化规律不明显, 地区差异较大, 大部分情况拉萨站Es出现概率最高; 对于全遮蔽和半遮蔽特性, 不同站也表现出不同的分布规律. 相似文献
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本文叙述确定总电子含量积分常数(Ωc)的一个方法。它是根据同步卫星信号相对法拉第旋转角(ΩR)随昼夜f02F2值的变化,运用最小二乘法计算Ωc对于f02F2的回归直线。此线的斜率正比于电离层等效板厚τ,直线与纵轴的交点给出Ωc。 相似文献
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本文对1983年满州里(磁纬38.07°)的测高仪资料和子午仪卫星资料进行了处理.前者主要是对F2层临界频率f0F2,而后者是对微分多普勒的总含量NT进行分析.得到满州里上空电离层之平均特性,以及磁暴期间电离层的一些异常变化.结果发现,满州里电离层的平均特性具有典型的季节异常,且f0F2和NT的变化呈现较好的一致性.满州里上空电离层的扰动大都发生在两分点季和冬季,且正相大多发生在冬季,双相大多发生在两分点季,负相大多发生在夏季和两分点季.得出1983年满州里暴时NT和f0F2相对于月中值偏移量的均方根值δNT和δf0F2都与磁Ap指数均方根值δAp之间存在一元线性相关. 相似文献
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利用Puerto Rico站(18.5°N, 67.2°W) 1997—2013 年的Es临界频率数据, 对该地区Es特性进行了分析. 结果表明: 临界频率 f0Es 日均值具有一定的16天周期性变化特征, 其可能是大气行星 波引起的; f0Es 随地方时的变化基本上呈一个波峰波谷结构, 波谷 位于06:00LT左右, 波峰位于14:00LT左右, 同时存在午夜和日落后异常高 值现象, 其分别与午夜南向风场减弱和夜间电场变化有关; 通过分析不同强 度Es, 发现潮汐风造成较低强度Es发生率的地方时分布与中等和高强度Es 明 显不同. 这些现象的相关物理机制尚需进一步研究论证. 相似文献
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基于低纬(海南)台站(19.5°N,109.1°E)电离层测高仪在2004年观测到的偶发E层(Es)临界频率(f0Es)和虚高(h'Es)数据,利用谱分析方法,给出了中国低纬地区Es层在全年和不同季节内的短周期变化特性.对全年数据谱分析表明,Es层除具有非常强的24h周期外,还具有显著的12h和8h周期.对不同季节内两个参数的谱分析进一步表明,8h周期主要出现在f0Es参数的春秋分季和夏末及在h'Es参数的几乎所有季节;6h周期主要出现在f0Es参数的11-12月.海南低纬Es层中具有显著的6h和8h周期特性,特别是这两个周期还能同时出现在冬季,这是以往研究中不曾发现的新结果.初步分析认为,Es层的6h和8h周期极可能是分别由1/4日和1/3日潮汐所造成的. 相似文献
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武昌哨声的传播特征及其与地磁活动的相关 总被引:1,自引:0,他引:1
本文利用武昌(磁纬19.2°N)连续三年的哨声观测资料,研究了武昌地区哨声传播的一般特征。着重对武昌哨声的传播路径进行了分析推断,并讨论了它们与地磁活动的相关特性。发现:武昌哨声的显著特征是色散与电离层f0F2有明显的正相关关系;其次常出现一类色散值稳定、出现率也很高的哨声。此外,对典型事件的分析及统计分析都表明武昌哨声出现率在地磁扰动时明显增高;哨声色散在磁暴急始后不久即有一个急剧的上升,上升幅度达18%至37%。 相似文献
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M. Pietrella M. PezzopaneC. Bianchi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Hourly systematic measurements of the highest frequency reflected by the sporadic-E layer (foEs) recorded from January 1976 to June 2009 at the ionospheric stations of Rome (Italy, 41.8°N, 12.5°E) and Gibilmanna (Italy, 37.9°N, 14.0°E) were considered to carry out a comparative study between the sporadic E layer (Es) over Rome and Gibilmanna. Different statistical analysis were performed taking into account foEs observations near the periods of minimum and maximum solar activity. The results reveal that: (1) independently from the solar activity, Es develops concurrently over extended regions in space, instead of being a spatially limited layer which is transported horizontally by neutral winds over a larger area; especially during summer months, when an Es layer is present at Rome, there is a high probability that an Es layer is also present over Gibilmanna, and vice versa; (2) Es layer lifetimes of 1–5 h were found; in particular, Es layers with lifetimes of 5 h both over Gibilmanna and Rome are observed with highest percentages of occurrence in summer ranging between 80% and 90%, independently from the solar activity; (3) latitudinal effects on Es layer occurrence emerge mostly for low solar activity during winter, equinoctial, and summer months, when Es layers are detected more frequently over Gibilmanna rather than Rome; (4) when the presence of an Es layer over Rome and Gibilmanna is not simultaneous, Es layer appearance both over Rome and Gibilmanna confirms to be a locally confined event, because drifting phenomena from Rome to Gibilmanna or vice versa have not been emphasized. 相似文献
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提出了一种基于决策树算法的自动识别Es层回波的方法以提高Es识别效率.通过自适应二值化以及中值滤波算法对频高图进行预处理,并提取有效的Es回波区域.利用Es层在虚高轴分布的规律,通过图像投影的方法选择出特征,将这些特征以及时间信息作为决策树算法的输入;通过人工识别方式为每幅频高图标明是否存在Es回波的标签,与决策树算法的输出进行比较.对训练集进行训练、剪枝,获取最接近人工识别结果的决策树,使用测试集对获取的决策树进行测试验证.本文使用云南普洱站(22.7°N,101.5°E)记录的频高图数据作为训练集,分别使用云南普洱站(22.7°N,101.5°E)和四川乐山站(29.5°N,103.7°E)的频高图数据作为测试集对该方法进行测试验证,结果表明该方法对普洱站和乐山站两地Es二跳回波的识别均具有较高的准确率,分别达到84.2%和82.8%. 相似文献
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海南地区电离层Es特性研究 总被引:1,自引:1,他引:0
利用中国科学院空间科学与应用研究中心海南电离层观测站DPS-4电离层测高仪2002年3月至2005年2月的观测数据,对太阳活动下降期间海南地区上空发生的偶发E层(Es)的逐年变化和季节变化进行了统计分析.主要结果表明,在这3年中海南地区Es事件出现次数逐年增加;Esr,Esq出现最频繁,其次是Esr,而Esc和Esf出现次数较少,出现次数最少的是Esh;Es事件在夏季出现最为频繁,秋季和冬季次之,春季最为稀少;各季节不同类型Es事件的出现率也不同,其中Esl和Esq一般在各季节占主导地位,Esr其次,Esc,Esf和Esh出现次数较少,尤其是Esf在秋季几乎没有出现.这些结果对于进一步研究Es产生的物理机制提供了探测基础,同时对于电离层空间天气预报模型的建立也具有重要的意义. 相似文献
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LiHui Qiu Xiaomin Zuo Tao Yu YangYi Sun Yifan Qi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(11):3606-3611
This study employs the Horizontal Wind model 2014 to calculate the intensity of the Vertical ion convergence (VIC) to examine the role of neutral wind shear in the global distribution of the Es occurrence rate. The global S4 observations from the FORMOSAT-3/COSMIC GPS Occultation Experiment (GOX) are used to derive global information on the Es occurrence. Both the simulation and observation suggest that the Es highly occurs in the mid-latitude regions of the summer hemisphere. 相似文献
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本文分析印度Trivandrum地磁台的约两个太阳黑子周期的地磁场水平分量小时值。在部分地消除了太阳黑子周期及一年周期变化后,发现了反向电集流出现率的QBO调制现象:QBO东风相反向电集流出现率增加;QBO西风相反向电集流出现率减小。据此讨论了反向电集流的形成机制,认为大气行星波在其上传过程中与太阳半日波或太阴半日波的相互作用,有可能导致两种半日波的放大和相位移动,并最终导致反向电集流的出现。 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(1):176-198
The influence of sudden stratospheric warming (SSW) on the ionosphere and ionospheric irregularities has been studied extensively over the years. However, majority of these investigations have been conducted using warming events originating from the northern hemisphere. Only a few studies have been done on ionospheric variations due to the Antarctic SSW events and to the best of our knowledge, there have not been any studies on southern hemisphere SSW and the occurrence of ionospheric irregularities. In this study, the occurrence of ionospheric irregularities during the 2019 minor Southern hemisphere (SH)/Antarctic SSW is investigated. The event occurs in a relatively calm solar and geomagnetic activity period which makes it possible to identify the effects of SSW on the occurrence of irregularities. Three ionosondes located in different latitudinal regions in Brazil as well as a network of ground-based GPS receiver stations located in both Brazil and Africa were used for this undertaking. Complimentary data from the same ionosonde stations using the same months from 2017 and 2018 were also used. On average more Spread-F was observed in 2019 than in 2017 or 2018 at all stations. ROT observations showed more occurrence in the Brazil sectors followed by West Africa and thenEast Africa. It was observed that the occurrence frequency decreased between 8% and 46 % from the pre-SSW phase to ascending/peak phases and from 2018 to 2019 for the peak phase. 相似文献