This work presents, for the first time, the analysis of the occurrence of ionospheric irregularities during geomagnetic storms at Tucuman-Argentina, a low latitude station in the Southern American longitudinal sector ( 26.9 ° S, 294.6 ° E; magnetic latitude 15.5 ° S), near the southern crest of the equatorial ionization anomaly (EIA). Three geomagnetic storms occurred on May 27, 2017 (a month of low occurrence rates of spread-F), October 12, 2016 (a month of transition from low to high occurrence rates of spread-F) and November 7, 2017 (a month of high occurrence rates of spread-F) are analyzed using Global Positioning System (GPS) receivers and ionosondes. The rate of change of total electron content (TEC) Index (ROTI), GPS Ionospheric L-band scintillation, the virtual height of the F-layer bottom side (h'F) and the critical frequency of the F2 layer (foF2) are considered. Furthermore, each ionogram is manually examined for the presence of spread-F signatures. The results show that, for the three events studied, geomagnetic activity creates favorable conditions for the initiation of ionospheric irregularities, manifested by ionogram spread-F and TEC fluctuation. Post-midnight irregularities are developed due to the presence of eastward disturbance dynamo electric fields (DDEF). For the storm of May, an eastward over-shielding prompt penetration electric field (PPEF) is also acting. This PPEF is added to the DDEF and produces the uplifting of the F region that helps trigger the irregularities. What is more, during October and November, strong GPS L band scintillation is observed associated with strong range spread-F (SSF), that is, irregularities29 extending from the bottom-side to the topside of the F region.

中文翻译：

---

阿根廷 EIA 南峰附近地磁风暴期间的传播 F 发生

这项工作首次对南美洲纵向扇区（26.9°S，294.6°E；磁纬 15.5°S）的低纬度站 Tucuman-Argentina 的地磁暴期间电离层不规则的发生进行了分析，靠近赤道电离异常 (EIA) 的南峰。3次地磁暴发生在2017年5月27日（传播-F发生率低的月份）、2016年10月12日（传播-F发生率从低到高转变的月份）和2017年11月7日（传播-F发生率低的一个月）使用全球定位系统 (GPS) 接收器和电离探空仪分析了高发生率的传播-F)。总电子含量变化率（TEC）指数（ROTI）、GPS电离层L波段闪烁、F层底面虚拟高度（h' F) 和 F2 层的临界频率 (foF2) 被考虑在内。此外，每个电离图都经过人工检查是否存在传播 F 特征。结果表明，对于所研究的三个事件，地磁活动为电离层不规则性的启动创造了有利条件，表现为电离图扩展-F 和 TEC 波动。由于东向扰动发电机电场 (DDEF) 的存在，出现了午夜后的不规则性。对于 5 月的风暴，向东的过度屏蔽瞬发穿透电场 (PPEF) 也在起作用。这个 PPEF 被添加到 DDEF 并产生 F 区域的隆起，这有助于触发不规则。此外，在 10 月和 11 月期间，观测到强 GPS L 波段闪烁与强距离扩展 F (SSF) 相关，即，