A single-station spectral model of the monthly median F-region critical frequency

Abstract

A new single-station monthly median model of the F-region critical frequency has been obtained. A goniometric functional approximation of the monthly median hourly values of f0F2 was accepted. The diurnal course of f0F2 was described by a constant component and four "tides". Only the influence of the annual and semiannual waves in the seasonal course of f0F2 was taken into account. The solar activity was depicted not only by the well known R12 - index, but also by the parameter KR, expressing the linear trend of the monthly mean values of the sunspots for the previous 12 months. The use of this new parameter gives an opportunity for the solar cycle investigated not to be divided into falling and rising parts. The main advantage of the presented monthly median spectral model is that the same approach could be used for the short-term prediction.