Abstract This paper presents the storm time comparative analysis of the performances of latest versions of global ionospheric models: International Reference Ionosphere (IRI) 2016, NeQuick 2 (NeQ) and the IRI extended to Plasmasphere (IRI-P) 2017 with respect to Navigation with Indian Constellation (NavIC) and Global Navigation Satellite System (GNSS) derived ionospheric Total Electron Content (TEC). The analysis is carried out under varying geomagnetic storm conditions during September 2017-November 2018, falling in the declining phase of solar cycle 24. TEC data from Indore, located near the northern crest of the Equatorial Ionization Anomaly (EIA) along with data obtained from the International GNSS Service (IGS) stations at Lucknow, located beyond the anomaly crest; Hyderabad, located between anomaly crest and magnetic equator and Bangalore, located near the magnetic equator have been analysed. The models generally overestimated during the storm periods with the exception of IRI-P, which matched (with an offset of about 3–5 TECU) with the enhancement observed on September 7, 2017 (during the strong storm of September 2017), from stations around the anomaly crest. No significant match was observed by the other two models. This match of IRI-P is attributed to the plasmaspheric contribution as well as the capability of assimilating measured TEC values into this model. In the present study, to the best of our knowledge, first comparisons of the empirical model derived TEC with NavIC and GNSS measurements from an anomaly crest location, combined with the IGS observations from the magnetic equator to locations beyond the anomaly crest, are conducted during geomagnetically disturbed conditions. Since NavIC satellites are at higher altitudes ( ~ 36000 km), the inclusion of NavIC data to the existing model could give better ionospheric predictions over the Indian subcontinent.

中文翻译：

---

地磁活动期间印度纵向扇区上使用 GNSS 和 NavIC 的电离层模型的比较研究

摘要 本文介绍了最新版本的全球电离层模型性能的风暴时间比较分析：国际参考电离层 (IRI) 2016、NeQuick 2 (NeQ) 和 IRI 扩展到等离子层 (IRI-P) 2017 在导航方面印度星座 (NavIC) 和全球导航卫星系统 (GNSS) 得出的电离层总电子含量 (TEC)。该分析是在 2017 年 9 月至 2018 年 11 月期间在不同地磁暴条件下进行的，处于太阳活动周期 24 的下降阶段。 来自印多尔的 TEC 数据，位于赤道电离异常 (EIA) 北峰附近，以及从位于勒克瑙的国际 GNSS 服务 (IGS) 站，位于异常峰顶之外；海得拉巴，位于异常峰顶和磁赤道和班加罗尔之间，位于磁赤道附近的已被分析。模型在风暴期间普遍高估了 IRI-P 除外，它与 2017 年 9 月 7 日（在 2017 年 9 月的强风暴期间）观测到的增强相匹配（偏移约 3-5 TECU），来自台站异常峰周围。其他两个模型没有观察到显着的匹配。IRI-P 的这种匹配归因于等离子体球的贡献以及将测量的 TEC 值同化到该模型中的能力。在本研究中，据我们所知，首先将 TEC 的经验模型与来自异常波峰位置的 NavIC 和 GNSS 测量值进行比较，并结合从磁赤道到异常波峰以外位置的 IGS 观测结果，在地磁干扰条件下进行。由于 NavIC 卫星位于更高的高度（~36000 公里），将 NavIC 数据包含到现有模型中可以更好地预测印度次大陆的电离层。