Ionospheric TEC variation based on GNSS data over the Arabian Peninsula and validation with the cubic spline interpolated GIM model

Abstract The study examined the ionospheric total electron content (TEC) variation based on global navigation satellites system (GNSS) stations located inside the Arabian Peninsula. An interpolation technique known as cubic spline is used and numerical investigation of TEC variation has been carried out from 2015 to 2017. First, global ionospheric map (GIM) data is interpolated with the help of the cubic spline interpolation method and then compared with observed GNSS TEC values. Correlation coefficients between observed and interpolated GIM TEC are very high (about 0.95), indicating a strong relationship. Normal correlation coefficients were not enough to establish their relationship; hence, the wavelet plot of the first four principal components of each series is plotted and again their correlation coefficients are studied. Although their correlation is good enough, the wavelet analysis points out the variability of each series, that they are not quite same. The low and high peaks of each series are different; which means, the lowest and highest peaks of both series do not occur at the same time. This can happen because there are few international GNSS service stations available over the Arabian Peninsula that becomes a cause of error in the interpolation of GIM data. This type of study indicates only simple comparisons such as correlation coefficient and a standard deviation is not enough for comparative analysis; we need to study it in depth by using suitable statistical tools.