The magnetosphere and ionosphere have a crucial interaction during severe geomagnetic storms. The Global Navigation Satellite System (GNSS) provides high-quality ionospheric observations with high temporal and spatial resolution, is generally preferred to investigate the ionospheric variation. In this study, the storm-time ionospheric response of the June 2015 severe storm (Dst min = −208 nT) was investigated by the Total Electron Content (TEC) data of the Global Ionosphere Maps (GIMs), COSMIC radio occultation (RO) and a chain of International GNSS Service (IGS) stations. GIMs were used to show the global TEC variation during the storm. COSMIC RO data were also utilized to investigate the TEC variation and electron density profiles in an anomaly area with a limited time interval. GNSS TEC data of the 16 IGS stations were utilized to investigate the ionospheric variability on different latitudes of hemispheres. The results showed that intense positive phases formed in high latitudes of the Southern Hemisphere (SH) and the western longitudes of the Northern Hemisphere (NH), especially over the North Atlantic Ocean until the main phase of the storm. Besides, negative phases were observed in high latitudes and eastern longitudes of the NH. During the recovery phase of the storm, positive phases were seen in the low latitudes of the SH and the ionospheric conditions calmed down in the entire SH after the depletion of these phases. Negative phases were also observed almost wholly covered in the NH, which denser in the European-African sector. As a particular result, the electron density profiles of COSMIC RO showed that the ionospheric phases of the June 2015 storm not only related to TEC values but also the altitude of maximum electron density.

中文翻译：

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基于GNSS的TEC观测对2015年6月22-23日强地磁暴全球电离层响应的调查

磁层和电离层在严重的地磁暴期间具有重要的相互作用。全球导航卫星系统 (GNSS) 提供具有高时空分辨率的高质量电离层观测，通常首选用于研究电离层变化。在这项研究中，2015 年 6 月强风暴 (Dst min = -208 nT) 的风暴时间电离层响应通过全球电离层图 (GIM)、COSMIC 无线电掩星 (RO) 的总电子含量 (TEC) 数据进行了调查以及一系列国际 GNSS 服务 (IGS) 站。GIM 用于显示风暴期间的全球 TEC 变化。COSMIC RO 数据也被用来研究有限时间间隔异常区域的 TEC 变化和电子密度分布。利用 16 个 IGS 站的 GNSS TEC 数据来研究半球不同纬度的电离层变异性。结果表明，在南半球高纬度地区（SH）和北半球西经地区（NH）形成了强烈的正相位，特别是在北大西洋上空，直到风暴的主要阶段。此外，在北半球高纬度和东经观测到负相位。在风暴的恢复阶段，在南半球的低纬度地区出现了正相位，在这些相位耗尽后，整个南半球的电离层条件趋于平静。还观察到负相几乎完全覆盖在 NH 中，在欧洲 - 非洲部分更密集。作为一个特殊的结果，