Zakharenkova Irina, Cherniak Iurii, Krankowski Andrzej
Space Radio-Diagnostic Research Center, University of Warmia and Mazury, 10-719 Olsztyn, Poland.
Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), 236006 Kaliningrad, Russia.
Sensors (Basel). 2021 Nov 21;21(22):7749. doi: 10.3390/s21227749.
The 25-26 August 2018 space weather event occurred during the solar minimum period and surprisingly became the third largest geomagnetic storm of the entire 24th solar cycle. We analyzed the ionospheric response at high latitudes of both hemispheres using multi-site ground-based GNSS observations and measurements onboard Swarm and DMSP satellites. With the storm development, the zones of intense ionospheric irregularities of auroral origin largely expanded in size and moved equatorward towards midlatitudes as far as ~55-60° magnetic latitude (MLAT) in the American, European, and Australian longitudinal sectors. The main ionospheric trough, associated with the equatorward side of the auroral oval, shifted as far equatorward as 45-50° MLAT at both hemispheres. The interhemispheric comparison revealed a high degree of similarity in a large expansion of the auroral irregularities oval towards midlatitudes, in addition to asymmetrical differences in terms of larger intensity of plasma density gradients and structures over the Southern auroral and polar cap regions. Evolution of the intense ionospheric irregularities and equatorward expansion of the auroral irregularities oval were well correlated with increases of geomagnetic activity and peaks of the auroral electrojet index.
2018年8月25日至26日的空间天气事件发生在太阳活动极小期，令人惊讶的是，它成为了整个第24太阳周期中第三大地磁风暴。我们利用多站点地基全球导航卫星系统（GNSS）观测以及“蜂群”（Swarm）卫星和“国防气象卫星计划”（DMSP）卫星上的测量数据，分析了南北半球高纬度地区的电离层响应。随着风暴的发展，极光起源的强烈电离层不规则区域在大小上大幅扩展，并向赤道方向移动至中纬度地区，在美国、欧洲和澳大利亚经度扇区达到约55 - 60°磁纬度（MLAT）。与极光椭圆赤道侧相关的主要电离层槽在两个半球都向南移动至45 - 50°磁纬度。半球间比较显示，极光不规则椭圆向中纬度大幅扩展具有高度相似性，此外，在南半球极光和极盖区域，等离子体密度梯度和结构强度更大，存在不对称差异。强烈电离层不规则现象的演变以及极光不规则椭圆向赤道方向的扩展与地磁活动的增加和极光电集流指数的峰值密切相关。
