Comparison of IRI-2016 model with IGS VTEC maps during low and high solar activity period

Abstract

Abstract This paper presents a comparison of IRI-2016 model vertical total electron content (VTEC) predictions and the International GNSS Service (IGS) VTEC maps during low and high solar activity, from 2000 to 2017. The comparison is carried out by investigation of the differences between the two data sets of VTEC values from a range of directions, such as all over the globe behavior, latitudinal latitudes as well as latitudinal and longitudinal behavior. The results show that there is a good consistency between IRI-2016 VTEC predictions and the IGS VTEC maps during low solar activity. IRI-2016 model is suitable for the scientific analysis of the general trend of the ionosphere. However, it extremely underestimates VTEC values in low latitudes during high solar activity. Due to the effect of EIA, the large differences are distributed in the low latitudes both in 2009 and 2015. The largest differences are distributed in the northern Indian Ocean and southern Atlantic Ocean according to the comparison of latitudinal and longitudinal behavior. Besides, IRI-2016 model also underestimates the VTEC values over the Pacific Ocean, especially during high solar activity. With the installation of more ground-based and space-based instruments, there is an opportunity for promoting the performance of IRI model in the equatorial ionization anomaly (EIA) region during high solar activity.