An EOF Based Empirical Model Of TEC Over Wuhan



In this paper, the empirical orthogonal function (EOF) analysis is introduced to develop an empirical model of monthly median of total electron content (TEC) over Wuhan in the years 1980-1990. Compared with the models constructed by Fourier series analysis, the EOF model is more valuable, and in comparison with International Reference Ionosphere 2000 (IRI 2000), it has higher precision. The result shows that the EOF base function may signify TEC diurnal variation and its coefficients signify, the long-term variation, that the first order EOF component may represent most TEC variations and the first three components constitute almost 99.7% of actual data, and that the standard deviation of the EOF model in 1986 (a solar minimum ) was 2.9313 TECU and in 1990 (a solar maximum) was 10.401 TECU, while of IRI, it was 4.7239 and 14.592 TECU. Thus it would be worthy to suggest that the EOF analysis be further used to the analysis and modeling of the joint multiple ionospheric parameters, including the important parameters such as NmF2, hmF2, over a single station or network stations. In addition, some experiments have been done to improve the external driver of the model. It reveals that taking F107A as the external driver of the model can improve its precision and stability.