In this study the statistics of ionospheric total electron content (TEC), derived from a GSV4004B dual-frequency Global Positioning System (GPS) receiver at Agartala station (23.450°N, 91.150°E) located in northern equatorial ionization anomaly (EIA) crest region of the Indian subcontinent, is reported with a performance analysis of IRI-2016 and IRI-2012 models during the ascending, maxima, declining and minima phases (2013-2018) of the solar cycle 24. Variations of model total electron content, as obtained from the IRI-2016 and IRI-2012 for the three options of topside electron density namely NeQuick, IRI 2001 and IRI 01-corr, are compared with the observed total electron content during different periods of interest viz. monthly, seasonal, annual and the correlations with solar activity parameters viz. sunspot number (SSN), 10.7 cm solar radio flux (F10.7), solar EUV flux, are also investigated. All the three options of IRI-2016 and IRI-2012 models show an earlier occurrence of diurnal maximum total electron content, as compared to the observed diurnal maximum GPS total electron content, throughout all the months during the complete period of observation. As the solar activity decreases (from 2015 to 2018), the model starts underestimating GPS total electron content, which becomes significantly high during the very low solar activity period of 2017-18 for all the months. IRI-2016 model underestimates the GPS total electron content before the hours of diurnal maximum and overestimates after the hours of diurnal maximum in the years from 2013-2018. IRI-2012 model underestimates the GPS total electron content before the hours of diurnal maximum and overestimates after the hours of diurnal maximum in the years from 2013-17 but overestimate during the whole day in the year of 2018. Overestimation by IRI-2012 is much more than that by IRI-2016 in the year of 2018. Predictions given by IRI-2016 are better than that given by IRI-2012 for our region. The seasonal mean maximum total electron content values are highest during the spring equinox months and lowest during the winter months except the year of 2014 and 2013. The correlation analysis, between the GPS total electron content and solar indices, show that the correlation coefficient is higher for the solar EUV flux, as compared to the sunspot number (SSN) and 10.7 cm solar radio flux (F10.7).

在这项研究中，电离层总电子含量 (TEC) 的统计数据来自位于赤道电离异常 (EIA) 北部的 Agartala 站 (23.450°N, 91.150°E) 的 GSV4004B 双频全球定位系统 (GPS) 接收器印度次大陆地区，报告了 IRI-2016 和 IRI-2012 模型在太阳活动周期的上升、最大值、下降和最小值阶段（2013-2018 年）的性能分析 24。模型总电子含量的变化，如从 IRI-2016 和 IRI-2012 中获得的三个顶部电子密度选项，即 NeQuick、IRI 2001 和 IRI 01-corr，与不同感兴趣时期观察到的总电子含量进行比较，即。每月，季节性，年度以及与太阳活动参数的相关性。太阳黑子号码（SSN），10。还研究了 7 cm 太阳射电通量 (F10.7)，即太阳 EUV 通量。IRI-2016 和 IRI-2012 模型的所有三个选项都显示，与观测到的昼夜最大 GPS 总电子含量相比，在整个观测期间的所有月份中，昼夜最大总电子含量出现得更早。随着太阳活动的减少（从 2015 年到 2018 年），该模型开始低估 GPS 总电子含量，在 2017-18 年所有月份的极低太阳活动期间，该总电子含量变得非常高。IRI-2016 模型在 2013-2018 年的昼夜最大值小时之前低估了 GPS 总电子含量，而在昼夜最大值小时之后高估了 GPS 总电子含量。IRI-2012模型在2013-17年度中低估了日最大小时前的GPS总电子含量，而在日最大小时后高估了GPS，但是在2018年的整天中高估了IRI-2012。在 2018 年，IRI-2016 的预测值超过了 IRI-2016。IRI-2016 给出的预测比 IRI-2012 给出的对我们地区的预测要好。除 2014 年和 2013 年外，季节平均总电子含量在春分最高，冬季最低。 GPS 总电子含量与太阳指数的相关分析表明，相关系数较高对于太阳 EUV 通量，与太阳黑子数 (SSN) 和 10.7 cm 太阳射电通量 (F10.7) 相比。