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51.
We consider the problem of automatically (and robustly) isolating and extracting information about waves and oscillations
observed in EUV image sequences of the solar corona with a view to near real-time application to data from the Atmospheric
Imaging Array (AIA) on the Solar Dynamics Observatory (SDO). We find that a simple coherence/travel-time based approach detects and provides a wealth of information on transverse
and longitudinal wave phenomena in the test sequences provided by the Transition Region and Coronal Explorer (TRACE). The results of the search are pruned (based on diagnostic errors) to minimize false-detections such that the remainder
provides robust measurements of waves in the solar corona, with the calculated propagation speed allowing automated distinction
between various wave modes. In this paper we discuss the technique, present results on the TRACE test sequences, and describe
how our method can be used to automatically process the enormous flow of data (≈1 Tb day−1) that will be provided by SDO/AIA.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
52.
New X-ray observations of the north polar region taken from the X-ray Telescope (XRT) of the Hinode spacecraft are used to analyze several time sequences showing small loop brightenings with a long ray above. We focus on
the formation of the jet and discuss scenarios to explain the main features of the events: the relationship with the expected
surface magnetism, the rapid and sudden radial motion, and possibly the heating, based on the assumption that the jet occurs
above a null point of the coronal magnetic field. We conclude that 2-D reconnection models should be complemented in order
to explain the observational details of these events and suggest that alternative scenarios may exist. 相似文献
53.
With the use of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph (LASCO) onboard the
Solar and Heliospheric Observatory (SOHO) from January 1996 through December 2005, it is found that, for the cyclical activity of CMEs, there is surprisingly
no equatorward drift at low latitudes (thus, no “butterfly diagram”) and no poleward drift at high latitudes, and no antiphase
relationship between CME activity at low and high latitudes. The cyclical behaviors of CMEs differ in a significant way from
that of the small-scale solar photospherical and chromospherical phenomena. Thus, our analysis leads to results that are inconsistent
with a close, physical relationship with small-scale aspects of solar activity, and it is suggested that there is possibly
a single so-called large-scale activity cycle in CMEs. 相似文献
54.
1997年1月6日爆发的日冕物质抛射(CME)到达地球时引起了强烈的地球物理效应,CME在行 星际空间传播时,广州的多方向μ介子望远镜观测到银河宇宙线强度的变化. 本文采用 小波分析方法分析了磁暴前后广州台宇宙线强度的频谱变化特征,结果表明,在磁暴前 宇宙线周期为16~32h的信号发生了较明显的变化,其中周期为24~32h的周期特征过去没有 被报道过. 广州台垂直方向宇宙线强度的谱在磁暴发生前48h就出现明显的变化,比各向异 性分析方法得到的时间提前量更大. 同时还分析了几个方向宇宙线强度的最强信号以及达到 最大值的时间,并进行了简要的分析与讨论. 相似文献
55.
本文分析讨论了太阳活动20、21周的冕洞及其边界区磁结构的变化。它包括:冕洞区光球磁场强度、磁极性的变化;冕洞面积与高速太阳风风速的关系;冕洞边界周围的环境。重点探讨太阳活动下降、极小相低纬、赤道冕洞区与其边界区磁结构的变化。 相似文献
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57.
We tested the validity of two current hypotheses on the dependence of climate change on solar activity. One of them states that variations in the tropospheric temperature are caused directly by changes of the solar radiance (total or spectral). The other suggests that cosmic ray (CR) fluctuations, caused by the solar/heliospheric modulation, affect the climate via cloud formation. Confronting these hypotheses with seven different sets of the global/hemispheric temperature reconstructions for the last 400 years, we found that the former mechanism is in general more prominent than the latter. Therefore, we can conclude that in so far as the Sun–climate connection is concerned tropospheric temperatures are more likely affected by variations in the UV radiation flux rather than by those in the CR flux. 相似文献
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59.
提出了一个新的太阳宇宙线日 -地传输的数学模型 ,它包括日冕粒子分布源和行星际传播方程 .根据对太阳宇宙线耀斑黑子群特征和耀斑相的观测 ,提出了多极性黑子湮没的两阶段日冕传输过程和传输方程 ,得到了与观测特征一致的日冕粒子分布源 .日冕传输的第一阶段 ,和太阳耀斑脉冲相的时间相当 ,加速粒子通过扩散很快均匀地分布在耀斑区 ,形成所谓快传播区 .第二阶段 ,加速粒子向快传播区以外的日冕区扩散并向行星际空间逃逸 ,形成慢传播过程 .日冕传输模型的数值结果和日冕传输的观测特征符合 .太阳宇宙线的行星际传播采用三维正交均匀各向异性方程描述 .最后把模型的数值结果与 1 997年 9月 2 4日事件的SOHO(SolarandHeliosphericObservatory)观测资料作了比较 .能较好地符合 . 相似文献
60.
本文联合SOHO和STEREO-A/B(三视角)日冕观测和太阳高能粒子(SEP)观测,分析了2007—2014年间169个快速(速度>900 km·s-1)、宽角度(>60°)日冕物质抛射(CME)及其先行CME和关联SEP事件.通过相关分析,给出了SOHO/EPHIN 25~53MeV及STEREO/HET 23.8~60 MeV能量范围的大SEP事件通量判断阈值,分别为0.01和0.014(cm2·s·sr·MeV)-1.三视角CME观测能有效地避免投影效应产生的twin-CME事件误判,统计得到单一视角确定twin-CME事件的误判率一般低于10%,最高不超过15%.基于三视角判断的twin-CME事件及SEP事件峰值强度,得到判断twin-CME事件的时间阈值最短约为9 h(9~13 h).single-CME产生的SEP事件强度与CME速度、动能的相关性明显高于twin-CME,并且三视角下的相关性结果与单视角类似.结果表明,一个主CME可能存在多个先行CME,依据单卫星观测判断先行CME时有一定的误判几率,但少数单个先行CME的误判并不影响基于单卫星的统计规律或统计结果.
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