GPS Data and SHF Modelling of the Low-Latitude Ionosphere

Abstract

The model is based on spherical harmonic functions (SHF), which provide a suitable representation for ionospheric behavior. The model is constructed by computing spherical harmonic coefficients through a weighted least square method, utilizing measured vertical total electron content (TEC) data from seventeen GPS Aided Geo Augmented Navigation stations.The accuracy of the SHF model is evaluated based on the residual error and compared with other standard grid models. The diurnal TEC variations are well represented by the SHF model, and it also demonstrates good performance in depicting ionospheric delays during the summer and autumn equinox seasons. Overall, the results indicate that the SHF model is effective in estimating ionospheric delays and provides valuable insights into ionospheric behavior in the Indian region.