共查询到19条相似文献，搜索用时 171 毫秒
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日冕物质抛射(Coronal Mass Ejection, CME)的检测是建立CME事件库和实现对CME在行星际传播的预报的重要前提. 通过Visual Geometry Group (VGG) 16卷积神经网络方法对日冕仪图像进行自动分类. 基于大角度光谱日冕仪(Large Angle and Spectrometric Coronagraph Experiment, LASCO) C2的白光日冕仪图像, 根据是否观测到CME对图像进行标记. 将标记分类的数据集用于VGG模型的训练, 该模型在测试集分类的准确率达到92.5%. 根据检测得到的标签结果, 结合时空连续性规则, 消除了误判区域, 有效分类出CME图像序列. 与Coordinated Data Analysis Workshops (CDAW)人工事件库比较, 分类出的CME图像序列能够较完整地包含CME事件, 且对弱CME结构有较高的检测灵敏度. 未来先进天基太阳天文台(Advanced Space-based Solar Observatory, ASO-S)卫星的莱曼阿尔法太阳望远镜将搭载有白光日冕仪(Solar Corona Imager, SCI), 使用此分类方法将该仪器产生的日冕图像按有无CME分类. 含CME标签的图像将推送给中国的各空间天气预报中心, 对CME进行预警. 相似文献
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太阳活动会引起输变电系统异常,特别是对超长距离输变电系统的危害尤其明显.根据SOHO/LASCO (Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph)的日冕物质抛射(Coronal Mass Ejection,CME)数据、华北电力大学和芬兰气象研究所获得的地磁感应电流(Geomagnetically Induced Current,GIC)数据以及地磁暴数据,分析研究了与GIC事件有关的对地晕状CME的重要观测特征和物理性质.按照对称性将晕状CME进行分类后,发现造成GIC事件的晕状CME主要有3类:完全对称型、亮度不对称型和外形不对称型.不同类型的全晕状CME驱动的GIC事件在强度、持续时间等方面特征各不相同.其中,亮度不对称型晕状CME很有可能对GIC事件影响最为严重.同时注意到GIC与地磁场随时间的变化率也具有较好的相关性. 相似文献
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《天文学进展》2016,(2)
日冕物质抛射(CME)是由太阳磁场驱动向行星际空间喷射等离子体物质和磁场的大尺度太阳爆发活动,是灾害性空间天气事件最主要的驱动源之一。朝着地球方向爆发的CME极易到达地球并造成灾害性空间天气,因此研究这类CME对于空间天气预报与太阳物理研究具有极为重要的意义。随着观测技术的发展,CME的观测及预报和研究工作取得了长足的进展。但由于常规观测手段与预报方法的局限,对朝着地球爆发的CME进行准确有效预报的目标至今仍未能实现。首先阐述CME与空间天气的关系,强调对CME预报研究的重要性;然后介绍预报研究中CME/ICME复杂的动力学过程,讨论这些过程对CME预报可能产生的影响;接着,回顾CME的常规观测手段,并讨论观测手段存在的不足;第4章,介绍CME主要的预报方法,同时讨论预报工作中存在的困难;第5章,讨论太阳雷达主动探测技术在日冕探测与CME预报研究中的可能应用前景;最后,总结CME预报研究现状,对预报研究工作中重要的问题进行综述,展望太阳雷达的未来应用。 相似文献
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目前观测的CME(日冕物质抛射)是其在天空平面的投影,这就导致CME的观测参量与真实参量之间存在一定的差异,比如说观测到的CME速度一般要比CME的真实速度小.运用基于锥状模型对CME的速度进行投影改正的方法,分析1996年9月到2007年9月(将近1个活动周)SOHO/LASCO日冕仪观测到的1 691个仅与耀斑相关的CME(简称FL类CME)和610个仅与暗条爆发相关的CME(简称FE类CME)投影改正前后的速度分布,得到如下结果:(1)投影改正前后,FL类CME和FE类CME的速度分布非常相似.且投影改正前后,两类CME的平均速度几乎相同; (2)投影改正前后,FL类CME和FE类CME速度的自然对数分布也非常相似. 相似文献
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目前观测得到的日冕物质抛射(coronal mass ejection,CME)只是其在天空平面的投影,其观测参量与真实参量之间存在一定的差异.而CME的速度是对其地磁效应有决定性影响的参量,因此对CME测量速度作投影效应改正是一个重要的研究课题.综述了近年来对CME测量速度进行投影效应改正的方法,并指出了这些投影效应改正方法中存在的一些问题和进一步的研究方向. 相似文献
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综述了近年来人们对磁浮现与耀斑，暗条，CME等太阳表面磁活动的相关关系的研究进展。概述了磁浮现的一些观测特性和理论研究现状。最后提出了今后对磁浮现做进一步研究工作的一些设想。 相似文献
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日冕物质抛射与共生射电爆发的地面和空间联测研究 总被引：1，自引：0，他引：1
引述了近年来太阳和空间物理的一大研究成果；产生日地空间射电爆发和地球物理响应的主因不是太阳耀斑，而是日冕物质抛射（CME），论述了射电爆发在研究CME中的作用；分析了1991-06-15CME事件中射电爆发和质子事件产生的物理过程；介绍了地面/空间对CME和共生射电爆发联测研究的新进展；提出了我国今后开展地面/空间联测研究的设想和建议。 相似文献
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日冕物质抛射(Coronal Mass Ejection, CME)是一种剧烈的太阳爆发现象, 它会对行星际空间造成严重扰动, 进而影响人类生产、生活. 基于CME的时空显著性, 将显著性检测方法引入到CME检测中, 利用结构化矩阵分解SOHO (Solar and Heliospheric Observatory)的大角度光谱日冕仪(Large Angle and Spectrometric Coronagraph Experiment, LASCO) C2的日冕图像对应的特征矩阵, 从中恢复出稀疏部分获得显著前景. 然后考虑CME运动时产生的时间显著性, 从而去除非CME结构(如冕流), 得到最终检测结果. 实验表明, 以人工目录协调数据分析中心(Coordinated Data Analysis Workshop, CDAW)检测结果为基准时, 所提方法不仅在检测CME数量上比计算机辅助跟踪软件包(Computer Aided CME Tracking Software package, CACTus)和太阳爆发事件检测系统(Solar Eruptive Event Detection System, SEEDS)有优势, 还在CME中心角度和张角宽度等特征物理参数测量上比CACTus和SEEDS更接近CDAW目录参考值. 相似文献
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Sophie A. Murray Jordan A. Guerra Pietro Zucca Sung-Hong Park Eoin P. Carley Peter T. Gallagher Nicole Vilmer Volker Bothmer 《Solar physics》2018,293(4):60
Coronal mass ejections (CMEs) and other solar eruptive phenomena can be physically linked by combining data from a multitude of ground-based and space-based instruments alongside models; however, this can be challenging for automated operational systems. The EU Framework Package 7 HELCATS project provides catalogues of CME observations and properties from the Heliospheric Imagers on board the two NASA/STEREO spacecraft in order to track the evolution of CMEs in the inner heliosphere. From the main HICAT catalogue of over 2,000 CME detections, an automated algorithm has been developed to connect the CMEs observed by STEREO to any corresponding solar flares and active-region (AR) sources on the solar surface. CME kinematic properties, such as speed and angular width, are compared with AR magnetic field properties, such as magnetic flux, area, and neutral line characteristics. The resulting LOWCAT catalogue is also compared to the extensive AR property database created by the EU Horizon 2020 FLARECAST project, which provides more complex magnetic field parameters derived from vector magnetograms. Initial statistical analysis has been undertaken on the new data to provide insight into the link between flare and CME events, and characteristics of eruptive ARs. Warning thresholds determined from analysis of the evolution of these parameters is shown to be a useful output for operational space weather purposes. Parameters of particular interest for further analysis include total unsigned flux, vertical current, and current helicity. The automated method developed to create the LOWCAT catalogue may also be useful for future efforts to develop operational CME forecasting. 相似文献
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An-Qin Chen Wei-Guo Zong 《中国天文和天体物理学报》2009,9(4)
Coronal mass ejection (CME) velocities have been studied over recent decades. We present a statistical analysis of the relationship between CME velocities and X-ray fluxes of the associated flares. We study two types of CMEs. One is the FL type associ- ated only with flares, while the other is the intermediate type associated with both filament eruptions and flares. It is found that the velocities of the FL type CMEs are strongly cor- related with both the peak and the time-integrated X-ray fluxes of the associated flares. However, the correlations between the intermediate type CME velocities and the corre- sponding two parameters are poor. It is also found that the correlation between the CME velocities and the peak X-ray fluxes is stronger than that between the CME velocities and the time-integrated X-ray fluxes of the associated flares. 相似文献
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Observations indicated that solar coronal mass ejections (CMEs) are closely asociated with reconnection-favored new flux emergence. By means of numerial simulations, a physical model of the emerging flux trigger mechanism for CMEs is proposed and explained well the observational results. Based upon this model, leaving the gravity and heat conduction out of consideration, the theoretical results of 2.5 dimensional numerical simulations indicate that whether a CME can be triggered depends on both the amount and the location of an emerging flux, besides its polarity orientation. Furthermore, the eruption and non-eruption regimes are presented in parameter space. By use of 15 filament eruption events in 2002 and 2003 and 44 non-eruption events in 2002, the results of a statistical study on the properties of emerging flux including its polarity orientation, its location and the amount of flux show that not all the emerging flux can make a filament to lose equilibrium and trigger the onset of a CME, The statistic results basically support the theoretical results of numerical simulations. This research provides useful information for the space weather forecast. 相似文献
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Distribution of latitudes and speeds of Coronal Mass Ejections (CMEs) in the northern and southern hemispheres in cycle 23,
from September 1996 to December 2006, have been analyzed. By calculating the actual probability of the hemispheric distribution
of the activity of the CME, we find that a southern dominance of the activity of the CME is shown to occur in cycle 23 from
September 1996 to December 2006. The CME activity occurs at all latitudes and is most common at low latitudes. This should
furnish evidence to support that CMEs are associated with source magnetic structures on a large spatial scale, even with transequatorial
source magnetic structures on a large spatial scale. The latitudinal distribution of CMEs in the northern and southern hemispheres
are no different from a statistical point of view. The speed distribution in the northern and southern hemispheres are nearly
identical and to a good approximation they can be fitted with a single lognormal distribution. This finding implies that,
statistically, there is no physical distinction between the CME events in the southern and northern hemispheres and the same
mechanism of a nonlinear nature acting in both the CME events in the northern and southern hemispheres. Our conclusions seem
to suggest that the northern-southern asymmetry of the CME events is related to the northern-southern asymmetry in solar dynamo
theory (Jiang et al. 2007). 相似文献
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We present in this paper a statistical study aimed at understanding the possible relationship between surface magnetic field
variation and CME initiation. The three samples studied comprise 189 CME-source regions, 46 active regions, and 15 newly emerging
active regions. Both large-scale and small-scale variations of longitudinal magnetic fields of these regions are studied.
To quantitatively study these variations, three physical quantities are calculated: the average total magnetic flux (ATF),
the flux variation rate (FVR), and the normalized flux variation rate (NFVR). Our results show that 60% of the CME-source
regions are found to have magnetic flux increases during 12 hours before CME eruptions and 40% are found to have magnetic
flux decreases. The NFVR of CME-source regions are found to be statistically identical to those of active regions, averaged
over 111 hours, and significantly smaller than those of newly emerging active regions. In addition 91% of the CME-source regions
are found to have small-scale flux emergence, whereas small-scale flux emergences are also easily identified in active regions
during periods with no solar surface activity. Our study suggests that the relationship between flux emergence and CME eruption
is complex and the appearance of flux emergence alone is not unique for the initiation of CME eruption. 相似文献
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综述日冕物质抛射的观测和持性，简短的前言之后，给出ＣＭＥ的发现经过及统计特性，着重介绍ＣＭＥ与其他种类太阳活动的相关。然后介绍ＣＭＥ的一般特性，包括可能与ＣＭＥ相关的一些物理过程的观测特性。初步结论是：ＣＭＥ是一种演变中的磁结构现象。 相似文献
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Solar coronal mass ejections (CMEs) show a large variety in their kinematic properties. CMEs originating in active regions and accompanied by strong flares are usually faster and accelerated more impulsively than CMEs associated with filament eruptions outside active regions and weak flares. It has been proposed more than two decades ago that there are two separate types of CMEs, fast (impulsive) CMEs and slow (gradual) CMEs. However, this concept may not be valid, since the large data sets acquired in recent years do not show two distinct peaks in the CME velocity distribution and reveal that both fast and slow CMEs can be accompanied by both weak and strong flares. We present numerical simulations which confirm our earlier analytical result that a flux‐rope CME model permits describing fast and slow CMEs in a unified manner. We consider a force‐free coronal magnetic flux rope embedded in the potential field of model bipolar and quadrupolar active regions. The eruption is driven by the torus instability which occurs if the field overlying the flux rope decreases sufficiently rapidly with height. The acceleration profile depends on the steepness of this field decrease, corresponding to fast CMEs for rapid decrease, as is typical of active regions, and to slow CMEs for gentle decrease, as is typical of the quiet Sun. Complex (quadrupolar) active regions lead to the fastest CMEs. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献