A global model of the ionospheric F2 peak height based on EOF analysis

Abstract

Abstract. The ionospheric F2 peak height hmF2 is an important parameter that is much needed in ionospheric research and practical applications. In this paper, an attempt is made to develop a global model of hmF2. The hmF2 data, used to construct the global model, are converted from the monthly median hourly values of the ionospheric propagation factor M(3000)F2 observed by ionosondes/digisondes distributed globally, based on the strong anti-correlation existed between hmF2 and M(3000)F2. The empirical orthogonal function (EOF) analysis method, combined with harmonic function and regression analysis, is used to construct the model. The technique used in the global modelling involves two layers of EOF analysis of the dataset. The first layer EOF analysis is applied to the hmF2 dataset which decomposed the dataset into a series of orthogonal functions (EOF base functions) E k and their associated EOF coefficients P k . The base functions E k represent the intrinsic characteristic variations of the dataset with the modified dip latitude and local time, the coefficients P k represents the variations of the dataset with the universal time, season as well as solar cycle activity levels. The second layer EOF analysis is applied to the EOF coefficients P k obtained in the first layer EOF analysis. The coefficients A k , obtained in the second layer EOF analysis, are then modelled with the harmonic functions representing the seasonal (annual and semi-annual) and solar cycle variations, with their amplitudes changing with the F 10.7 index, a proxy of the solar activity level. Thus, the constructed global model incorporates the geographical location, diurnal, seasonal as well as solar cycle variations of hmF2 through the combination of EOF analysis and the harmonic function expressions of the associated EOF coefficients. Comparisons between the model results and observational data were consistent, indicating that the modelling Zhang (zhangml@mail.iggcas.ac.cn) technique used is very promising when used to construct the global model of hmF2 and it has the potential of being used for the global modelling/mapping of other ionospheric parameters. Statistical analysis on model-data comparison showed that our constructed model of hmF2, based on the EOF expansion method, compares better with the observational data than the model currently used in the International Reference Ionosphere (IRI) model.

Modeling ionospheric <I>fo</I>F2 by using empirical orthogonal function analysis

“…Dvinskikh (1988) first introduced EOF analysis into the empirical modeling of the ionospheric parameters. It has been confirmed by many researchers that EOF analysis is a powerful method for ionospheric modeling and data analysis (e.g., Singer and Dvinskikh, 1991;Daniell et al, 1995;Matsuo et al, 2002Matsuo et al, , 2005Marsh et al, 2004;Zhao et al, 2005;Zapfe et al, 2006;Liu et al, 2008;Mao et al, 2008;Zhang et al, 2009;Matsuo and Forbes, 2010, and more). According to EOF theory, the variation of the ionospheric parameters are attributed to different factors which can be extracted and separated in terms of their relative "contribution" with respect to ionospheric parameters.…”

“…This makes EOF analysis method a highly effective way of empirical modeling not only by greatly reducing the modeling parameters but also by considerably saving the computation time compared with other expansion methods. For further details of EOF decomposition, readers may refer to Dvinskikh (1988), Xu and Kamide (2004), and Zhang et al (2009).…”

“…Of particular intention is concentrated on modeling the ionospheric parameters such as foE, foF2, hmF2, and M(3000)F2, etc. based on empirical orthogonal function analysis (e.g., Dvinskikh, 1988;Liu et al, 2008;Zhang et al, 2009). In this paper, we will focus on constructing single station model of ionospheric foF2 for Wakkanai (Geographic 45. (Liang, 1990;Adeniyi et al, 2003;Bilitza et al, 2006;Vlasov and Kelley, 2010).…”

Global median model of the F2-layer peak height based on ionospheric radio-occultation and ground-based Digisonde observations

“…So, Zhang et al (2009Zhang et al ( , 2014 use the empirical orthogonal functions to develop a global h m F2 model. However, the first work uses the indirect derivation of h m F2 from M(3000)F2, f o F2 and f o E. In the following work (Zhang et al, 2014) the authors used the combined data from the satellite radio-occultation measurements and the 10 ground-based ionospheric sounders.…”

A new global model for the ionospheric F2 peak height for radio wave propagation

“…Another approach of ionospheric parameter modelling based on empirical orthogonal function (EOF) analysis of the observational data set is studied by Liu et al (2008), and Zhang et al (2009). Furthermore, Gulyaeva et al (2008) recently developed a numerical model of hmF2 using about 90 000 electron density profiles derived from observations taken by topside sounder satellites ISIS1, ISIS2, IK19 and Cosmos-1809during 1969-1987 In this paper, we derive an empirical hmF2 model based on non-linear least squares technique.…”