SIMP-1 model: Mapping of fo F2 monthly medians over the Northern Hemisphere

Abstract

The System of Ionosphere Monitoring and Prediction (SIMP-1), an empirical model of the monthly median state of the ionosphere, includes several blocks for a global description of the ionosphere in the D and E regions and F1 and F2 layers. In this paper, the principles of the creation of the block of the foF2 monthly medians over the Northern Hemisphere, including local models of foF2 based on data from groundbased ionospheric sounding stations and the multiquadric method of mapping, are described. It is shown that the use of effective ionospheric indices of solar activity, rather than the traditionally used sunspot number R₁₂ makes it possible to increase the accuracy of the approximated dependence of foF2 median values on the solar activity level. The local foF2 models are created in the form of a function of the ionospheric index T over 75 stations of the Northern Hemisphere for 12 months of the year and 24 moments of Universal Time. The multiquadric method, which enables the recovery of a surface exactly through foF2 values at the given station, is used for the foF2 mapping. A comparison of the SIMP-1 model with the CCIR, Prognoz MPCh, and SMI-88 (which is an ionospheric standard in RF) is performed. It is shown that the local models show a high accuracy of approximation of the foF2 observed variations, whereas the multiquadric method provides, on the whole, a higher accuracy of description of the foF2 planetary distribution. The results confirm the high efficiency of the proposed approach.