Abstract

A wide range of changes in parameters of the low-latitude ionosphere has been revealed during the periods of three intense geomagnetic storms that occurred in different seasons of 2015. Ionospheric parameters, according to the data from ionosondes (ionograms), include critical frequencies fоF2, foE, and foEs; the degree of diffuseness of signals; the presence of lateral reflections; the multihop pattern of vertical-incidence ionospheric sounding (VIS); the effect of blocking signal reflections from the F2 layer by the Es layer; and the presence of М-type modes. The analysis was based on the data from ionosondes at low-latitude stations in Athens, Greece, and Nicosia, Cyprus. The following results were obtained. The spring storm was characterized by the presence of lateral reflections, greater diffuseness in the F2 layer, and an increased number of reflections during VIS during daytime hours compared to nighttime hours. The summer storm was characterized by very frequent appearance of sporadic Es layers, the occurrence of М-type reflections, and the effect of blocking. The specific analysis of the winter storm shows that the thick Es layer stretched along the Earth’s surface over a distance of no less than 800 km and had a lifetime of about 7 h.

中文翻译：

---

低纬电离层中地磁风暴的影响

摘要

宽范围的在低纬度电离层中的发生在2015年电离层参数不同季节3级强烈地磁风暴期间已经揭示的参数的变化，根据来自ionosondes（电离图）中的数据，包括临界频率˚F о F 2，f o E和f o Es；信号的扩散程度；存在侧向反射；垂直入射电离层测深（VIS）的多跳模式；Es层阻止信号从F 2层反射的效果；和М的存在类型的模式。该分析基于希腊雅典和塞浦路斯尼科西亚低纬度站的电离声测仪的数据。获得了以下结果。与夜间相比，春季暴风雨的特征是存在横向反射，F 2层中的弥散性更大，并且在VIS白天白天的反射次数增加。夏季风暴的特征是非常频繁地出现零星的Es层，出现М型反射和阻塞效应。对冬季风暴的具体分析表明，厚厚的Es层沿地球表面延伸了不少于800 km的距离，寿命约为7 h。