Validation of Global TEC Mapping Model Based on Spherical Harmonic Expansion towards TEC Mapping over Egypt from a Regional GPS Network

摘要

Unlike the interpolation process of Total Electron Content (TEC) maps made by Ionospheric Associate Analysis Centers (IAAC) over areas have no International GNSS Service (IGS) stations, A TEC mapping tool with a temporal resolution of 1 h based on GPS dual frequency observations was developed. This tool was written under MATLAB environment and can be used globally to produce GIMs from local GPS networks in several areas with low number of IGS stations or without. As the geomagnetic storm field affect directly on the TEC, three stormy days and other three quiet days were chosen for validating the developed model. The estimated TEC resulted from the model firstly was compared with Center for Orbit Determination in Europe (CODE) TEC results using the RINEX data of ten Eurobian IGS stations. The comparison of the results shows a convergence between CODE and GTM estimated TEC. The maximum differences were 2.52 TECU and 1.31 TECU for the stormy and quiet days, respectively. Then the new models was used to generate TEC maps of Egypt using a regional network with interval of 1 h have a high temporal resolution compared to global ionosphere maps which are produced by several analysis centers.