Climatological analysis and modeling of the ionospheric global electron content

In this paper, we calculate the ionospheric global electron content (GEC) from the GPS TEC data along the geographic longitude 120°E during the period of 1996–2004, and investigate the relationship between GEC and 10.7 cm solar radio flux F_10.7 and its seasonal dependence with partial correlation analysis. Our results show that GEC is closely correlated with solar activity index F_10.7 and is also related with annual and semiannual variations. An empirical GEC model driven by those factors is then to examine the influences of different solar activity proxies for the model input. The results suggest that GEC mainly depends on solar activity and the seasonal variations; the latter is also modulated by solar activity. Furthermore, the magnitude of semiannual variation is a little greater than that of annual variation. Our empirical GEC model is proved to be better than the model proposed by Afraimovich et al. Supported by the Knowledge Innovation Project of Chinese Academy of Sciences (Grant No.KZCX3-SW-144), the National Natural Science Foundation of China (Grant No.40636032), and the National Important Basic Research Project (Grant No.2006CB806306)