The comparative analysis of measured and modelled Vertical Total Electron Content (VTEC) in low, mid and high latitude assists in the correction of Global Positioning System (GPS) measurements. In this study, we compare VTEC from GPS and International Reference Ionosphere (IRI) models (2007, 2012 and 2016) over mid latitude Sukkur (Lat \(27.7^{\circ}~\text{N}\), Long \(68.8^{\circ}~\text{E}\)) region in Pakistan during the final phase of the solar cycle 24 (2019–2020). We investigated the comparison in the form of ionospheric VTEC deviation during diurnal, monthly and seasonal analyses in measured and modelled values over the mid latitude region. The diurnal analysis shows that the measured VTEC in low magnetic activity days’ correlates with IRI-2016 as compared to IRI-2007 and IRI-2012. Whereas, IRI-2016 matches more than IRI-2007 and IRI-2012 in monthly values with minimum deviation. Moreover, the seasonal variations depict maximum variability in the spring season between measured and modelled VTEC over Sukkur. Similarly, maximum correlation (\(R>9.0\)) is noted between measured and modelled VTEC in low magnetic activity days than high solar activity days, whereas the correlation is \(R<9.0\) between ionosphere measured and modelled VTEC during high solar activity days in 2019–2020. All these investigations aid in correcting the ionospheric errors over low latitude Sukkur region.

在低纬度，中纬度和高纬度中对测得的和建模的垂直总电子含量（VTEC）进行比较分析有助于校正全球定位系统（GPS）的测量结果。在这项研究中，我们比较了GPS和国际参考电离层（IRI）模型（2007年，2012年和2016年）在Sukkur中纬度（纬度\（27.7 ^ {\ circ}〜\ text {N} \），长\（ 68.8 ^ {\ circ}〜\ text {E} \））区域在太阳周期24（2019–2020）的最后阶段。我们在中纬度地区的每日和每月分析中，以电离层VTEC偏差的形式调查了测量值和模型值中的电离层VTEC偏差。昼夜分析表明，与IRI-2007和IRI-2012相比，在低磁活动天数中测得的VTEC与IRI-2016相关。相比之下，IRI-2016在每月值方面比IRI-2007和IRI-2012匹配得更多，且偏差最小。此外，季节变化描绘了Sukkur上测量和建模的VTEC之间的春季最大变化。同样，在低磁活动天数比高太阳活动天数下，测量和建模的VTEC之间存在最大相关性（\（R> 9.0 \）），而相关性为在2019–2020年高太阳活动日，电离层测得的VTEC与模型VTEC之间的\（R <9.0 \）。所有这些研究都有助于纠正低纬度Sukkur区域的电离层误差。