Improvement of equatorial density distribution of the global core plasma model using GPS-derived TEC

The global core plasma model (GCPM) is a realistic electron density model of the inner magnetosphere. By using long-term total electron content (TEC) data obtained from several GPS tracking stations along the equator and a low Earth orbit satellite, the accuracy of the GCPM equatorial density is examined. According to the statistical analysis of the GPS TEC, we found a remarkable feature in bias errors in the GCPM-derived TEC. Most of the errors are found to distribute in the topside ionosphere due to the simple representation of the density there.