日照边缘区域电离层对耀斑的响应特点研究

Study of the Response of the Ionosphere Over Sun-Lit Boundary Region to Solar Flare

利用MSIS模型和背景太阳辐射谱模型,在一定大耀斑辐射谱假设的前提下,计算了耀斑期间日照边缘区域的电子产生率,分析了这一区域电离层电子密度的变化特点．结果表明,大耀斑期间在日照边缘区域,甚至大于太阳天顶角90°的区域都有明显的电子产生率的增加．从不同太阳天顶角处的电子产生率剖面的形态来看,随着天顶角的增加最大电离率减少,但高度增加．计算还显示了在太阳天顶角小于90°的区域内电子产生率的垂直分布有明显的双峰结构,这种结构对应着电离层的E区和F区,但在天顶角大于90°区域, F区的电子产生率要大得多．考虑到离子和电子的复合过程,这一区域的总电子含量的增加主要产生在高F区．

Using the model of solar irradiance spectrum during large solar flare and MSIS, the electron production rate during flare over sun-lit boundary region is calculated. It is found that during large solar flare the obvious increase of electron production rate over sun-lit boundary region occurs that, in turn cause the sudden increase of total electron content observed in this region. From the profile of electron production rate in different solar zenith angle, it can be seen that the largest electron production rate decreases with the zenith angle increasing and the heights of peak electron production rate increase. Calculation shows that the double peaks exist in the profile of electron production rate when the zenith angle less than 90° that correspond to ionospheric E and F region. Nevertheless, the peak value of electron production rate in F region is more larger than that in E region when zenith angle larger than 90°. Considering the feature of recombination of electron and ion in different ionospheric regions, it can be concluded that the sudden increase of total electron content observed by GPS mainly occurs in F region over sun-lit boundary region.