用甚低频方法预测太阳高能粒子沉降的研究

发布时间：2018-01-26 18:34

本文关键词： 太阳高能粒子太阳耀斑甚低频 SPA 最小二乘法　出处：《河南师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：太阳高能粒子沉降对地球的危害极大,采取有效办法对其进行提前预报具有重大意义。本文针对目前国内外预测太阳高能粒子沉降的方法的缺陷,提出了一种受天气变化影响较小、成本较低的甚低频法预报太阳高能粒子沉降事件。太阳耀斑爆发时释放的大量X射线会破坏电离层D层的电离度,造成低电离层等效高度发生变化,致使在地——低电离层波导中传播的甚低频(VLF)信号相位出现突然相位异常(SPA)现象。本文利用VLF信号的相位异常幅度,反推低电离层等效高度变化量,进而判断太阳耀斑爆发时X射线峰值流量,最后根据太阳耀斑与高能粒子沉降事件的相关性,对太阳高能粒子沉降事件的发生情况进行预测。实验观测了1991年全年奥米茄导航系统G台和E台至南极中山站这两条传播路径上VLF信号发生SPA现象的时间与幅度,通过与美国国家地球物理数据中心发布的GOES卫星观测的太阳耀斑发生情况进行对比分析发现,当VLF信号观测路径有一部分处于白天时段时,其相位对太阳耀斑的发生就非常敏感,VLF信号相位异常的时间几乎与太阳耀斑发生的时间同步,并且相位异常幅度与太阳耀斑级别正相关。由VLF相位的异常幅度可计算出低电离层等效高度下降量,然后利用MATLAB中最小二乘法的原理对低电离层等效高度下降量与X射线峰值流量之间的相关性进行拟合,结果得出两者之间呈指数关系。经VLF法对太阳耀斑和高能粒子沉降发生情况进行观测研究发现,太阳风的速度大约为600~800km/h,太阳高能粒子沉降通常在太阳耀斑爆发后50~70小时才能到达地球附近。这表明,仅根据VLF信号的相位异常幅度,便可很方便的对太阳耀斑的发生情况做出相对及时、准确的判断,进而对太阳高能粒子沉降的发生时间做出至少提前2~3天的预报,证明了用VLF方法预测太阳高能粒子沉降的可行性。
[Abstract]:Solar high-energy particle subsidence is very harmful to the earth. It is of great significance to take effective methods to predict the solar high-energy particle subsidence in advance. This paper aims at the defects of the current methods of predicting solar high-energy particle deposition at home and abroad. A very low frequency method is proposed to predict the solar high-energy particle subsidence events, which is less affected by the weather changes and less costly. The ionizing degree of ionosphere D will be destroyed by a large amount of X-ray emitted by solar flares. Resulting in changes in the equivalent height of the low ionosphere. The phase of very low frequency (VLF) VLF signal propagated in a ground-low ionospheric waveguide is characterized by sudden phase anomaly (spa). In this paper, the amplitude of phase anomaly of VLF signal is used. The change of the equivalent height of the ionosphere is pushed back, and the peak X-ray flux of solar flares is estimated. Finally, the correlation between solar flares and high-energy particle deposition events is discussed. The occurrence of solar high-energy particle deposition events was predicted. The occurrence of VLF signal on the two propagation paths of Omega navigation system G and E to Zhongshan station in Antarctica on 1991 was observed experimentally. The time and magnitude of the elephant. By comparing the solar flares observed by the GOES satellite with the National Geophysical data Center of the United States, it is found that when part of the observed path of the VLF signal is in the daytime period. Its phase is very sensitive to the occurrence of solar flares. The time of phase anomaly of VLF signal is almost synchronized with that of solar flares. The phase anomaly amplitude is positively correlated with the solar flare level. The equivalent height drop of the low ionosphere can be calculated from the anomalous amplitude of the VLF phase. Then the correlation between the decrease of equivalent height of low ionosphere and the peak X-ray flux is fitted by using the principle of least square method in MATLAB. The results show that there is an exponential relationship between the solar flares and the deposition of high-energy particles by VLF method. It is found that the velocity of solar wind is about 600 ~ 800km / h. Solar high-energy particles usually do not reach Earth's vicinity until 50 to 70 hours after the solar flares erupt, indicating that the amplitude of phase anomalies is only based on the VLF signal. It will be convenient to make a relatively timely and accurate judgment on the occurrence of solar flares, and then forecast the time of solar high-energy particles subsidence at least 2 or 3 days in advance. It is proved that the VLF method is feasible to predict the solar high energy particle subsidence.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P182

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