The ionospheric total electron content (TEC) is a significant parameter for scientific studies of the ionosphere and space weather. Ground‐based Global Navigation Satellite System (GNSS) station network provides an opportunity for modeling the ionospheric TEC with high accuracy. Based on global ionospheric TEC maps, by using data from the International GNSS Service (IGS) stations for 21 years (from 1998 to 2018), we establish an ionospheric climate index (ICI) for representing the general state of the ionosphere. In addition, we build a multiple linear regression model for fitting ICI using the SSN, F_10.7, Ap, and Dst indices and upper atmospheric wind field. We quantitatively analyze the contribution of these factors to ICI time series. ICI during the past six solar cycles, namely, from 1958 to 2018, are presented, which are assigned as the adjectives (cold, cool, mild, warm, hot, and sizzling) for ionospheric climatology studies. This new index is a very promising representative of day‐to‐day variations of middle‐ and low‐latitude ionosphere.

中文翻译：

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基于GNSS的电离层气候指数

电离层总电子含量（TEC）是电离层和太空天气科学研究的重要参数。地面全球导航卫星系统（GNSS）站网为电离层TEC的高精度建模提供了机会。基于全球电离层TEC图，通过使用国际GNSS服务（IGS）站21年（从1998年到2018年）的数据，我们建立了代表电离层总体状态的电离层气候指数（ICI）。另外，我们使用SSN，F _10.7，Ap和Dst建立了拟合ICI的多元线性回归模型指数和高层大气风场。我们定量分析这些因素对ICI时间序列的贡献。介绍了过去六个太阳周期（即1958年至2018年）中的ICI，它们被指定为电离层气候学研究的形容词（冷，凉，温和，温暖，炎热和嘶嘶作响）。这个新指数非常有希望地代表中低纬度电离层的日常变化。