低电离层对2017年9月不同等级耀斑事件的响应分析

Analysis of the response of the low ionosphere to flares of different magnitudes in September 2017

基于地球静止环境业务卫星(GOES)观测的X射线通量和斯坦福太阳研究中心提供的甚低频(VLF)信号数据,借助时间序列分析方法,本文分析了低电离层对第24太阳活动周内最大的太阳耀斑事件的响应问题。结果表明:①对于C级和M级耀斑事件,不同接收站台接收的VLF信号的强度所表现的起伏波动情况有所不同,美国拉穆尔台站(NML)-美国迪卡尔布接收站(YADA)路径上的VLF信号响应M级耀斑事件的灵敏性更强也更典型,其他两条路径的响应不够明显,而对于X级耀斑事件,三条路径上的VLF信号的响应均异常显著;②在不同发射路径上,X级耀斑事件对电离层VLF信号的影响程度会受到信号传播路径长度的影响,NML-美国伊斯波特接收站(CSSC)路径上电离层VLF信号受X级太阳耀斑影响的情况最为明显,澳大利亚埃克斯茅斯台站(NWC)-CSSC路径上电离层VLF信号的响应程度较低。

Based on X-ray fluxes observed by geostationary operational environmental satellite(GOES)and very low frequency(VLF)signal data from the Stanford Solar Research Center,this paper analyzed the response of the low ionosphere to the largest solar flare event in the 24th solar cycle with the help of time series analysis methods.The results showed that:①For C-class and M-class flare events,the intensity of VLF signals received by different receiving stations showed different fluctuations.VLF signals on the NML-YADA path were more sensitive and typical in response to M-class flare events,while the responses of the other two pathways were not obvious enough.For X-class flare events,the response of VLF signals on all three paths was unusually significant.②In different emission paths,the degree of influence of X-class flare events on ionospheric VLF signals would be affected by the length of the signal propagation path.Ionospheric VLF signals on the NML-CSSC path were most affected by X-class solar flares,and ionospheric VLF signals on NWC-CSSC radial were less responsive.