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221.
Bimal Pande Seema Pande Ramesh Chandra Mahesh Chandra Mathpal 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(2):777-785
We present here a study of Solar Energetic Particle Events (SEPs) associated with solar flares during 2010–2014 in solar cycle 24. We have selected the flare events (≥GOES M-class), which produced SEPs. The SEPs are classified into three categories i.e. weak (proton intensity?≤?1?pfu), minor (1?pfu?<?proton intensity?<?10?pfu) and major (proton intensity?≥?10?pfu). We used the GOES data for the SEP events which have intensity greater than one pfu and SOHO/ERNE data for the SEP event less than one pfu intensity. In addition to the flare and SEP properties, we have also discussed different properties of associated CMEs. 相似文献
222.
J.H. Tian J.C. Zhang Z.Y. Pu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,36(12):2372-2377
Intense geomagnetic storms (Dst < −100 nT) usually occur when a large interplanetary duskward-electric field (with Ey > 5 mV m−1) lasts for more than 3 h. In this article, a self-organizing map (SOM) neural network is used to recognize different patterns in the temporal variation of hourly averaged Ey data and to predict intense storms. The input parameters of SOM are the hourly averaged Ey data over 3 h. The output layer of the SOM has a total of 400 neurons. The hourly Ey data are calculated from solar wind data, which are provided by NSSDC OMNIWeb and ACE spacecraft and contain information on 143 intense storms and a fair number of moderate storms, weak storms and quiet periods between September 3, 1966 and June 30, 2002. Our results show that SOM is able to classify solar wind structures and therefore to give timely intense storm alarms. In our SOM, 21 neurons out of 400 are identified to be closely associated with the intense storms and they successfully predict 134 intense storms out of the 143 ones selected. In particular, there are 14 neurons for which, if one or more of them are present, the occurrence probability of intense storms is about 90%. In addition, several of these 14 neurons can predict big magnetic storm (Dst −180 nT). In summary, our method achieves high accuracy in predicting intense geomagnetic storms and could be applied in space environment prediction. 相似文献
223.
基于三维不可压缩电阻性MHD方程,在长柱形位型下,数值研究了电阻撕裂模不稳定性所引起的磁场重联过程。研究结果表明,撕裂模的非线性相互作用和耦合,将产生许多模式的强裂解稳和导致快速的磁场重联。这一过程的进一步发展,导致具有螺旋形结构,不同模式的磁岛磁力线重叠,从而引起较大区域内的磁场各态经历和磁力线随机走向,形成撕裂模端动。 相似文献
224.
Eijiro Hiei 《Space Science Reviews》1994,70(1-2):189-192
X-ray emission from solar coronal loops changes on two different timescales: a) flare loops and transient active region brightenings show a rapid variability, b) quiet region loops are quasi-steady and change only slowly with time. This different time behavior has been analyzed on the basis of Yohkoh SXT observations and we report here on the results from our analysis, mainly focussing on quiet loop variability. 相似文献
225.
介绍了1982年12月30日太阳视面上S10W20处伴随耀斑产生的日浪形态,并给出其速度场随时间演变的特征.光谱观测结果表明,日浪上升过程中有旋转运动,速度为20—30km/s,旋转速度随时间而减小. 相似文献
226.
K. Shibasaki T. Takano S. Enome H. Nakajima M. Nishio Y. Hanaoka C. Torii H. Sekiguchi T. Bushimata S. Kawashima N. Shinohara H. Koshiishi Y. Shiomi 《Space Science Reviews》1994,68(1-4):217-224
The early phases of three flares, observed by the Nobeyama Radio Heliograph, are studied. Nonthermal and thermal radio sources are identified by comparison with soft X-ray images taken by the Soft X-ray Telescope onboard the Yohkoh satellite. Two of the flares are mainly of nonthermal origin and their location coincides with one of the footpoints of soft X-ray loops. Another flare has both thermal and nonthermal components which start to brighten simultaneously. This suggests that particle acceleration and plasma compression develop simultaneously. 相似文献
227.
LANDSAT-7卫星的主要有效载荷——改进型主题测绘仪(Enhanced Thematic Map-per Plus)ETM 是在landsat-4和Landsat-5卫星的主要有效载荷主题测绘仪(Thematic Map-per)的基础上改进的。ETM 相对TM的主要不同之处在于它增加了1个金色谱段和2个增益区域,增加了太阳定标器,并提高了红外谱段的分辨率,文章简要介绍ETM 的性能和主要组件。 相似文献
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230.
本文提出了一种求解二维理想磁流体力学方程组的组合格式-网格方法。该方法在保证一定精度的前提下稳定性好,计算量小。文中使用该方法算得了子午面太阳风的盔状流动解。以该解作为初态,研究了盔状冕旒位形对日冕抛射物运动的影响,发现该位形使得抛射物向低纬赤道方向偏转,较好地解释了观测结果。 相似文献