Establishment of N m F 2 empirical model in the northern hemisphere based on COSMIC occultation data

Abstract

Ionospheric peak value of F2 layer (N (m) F (2)) is an important parameter in the ionosphere, which has important applications in short-wave communication, ionospheric modeling and so on. In this paper, the empirical orthogonal function (EOF) decomposition method is used to analyze the N (m) F (2) obtained from the occultation data. Daily spatial distribution of N (m) F (2) at the same time is relatively even. Variance of first modal is much larger than the other modals. A local wavelet power spectrum (LWPS) method is applied to analysis the cycle of F (10.7) index and time coefficient of first modal. The result shows that they have similar cycle distribution, indicating that F (10.7) index is the main factor affecting variation of N (m) F (2). A function is established between the tine coefficient of first modal and F (10.7) index, average F (10.7) index value of early 81 days f (p) by least squares method. The results show that contribution coefficient of f (p) is negative which indicates that f (p) has an inert effect existing in the ionosphere. Contribution coefficient of F (10.7) is positive, which is consistent with the fact that it has an anomaly in winter/spring seasons. In summary, it is feasible to establish a mid-latitude empirical N (m) F (2) model in northern hemisphere based on occultation data and EOF decomposition method.