Calculation of the Regular Variations of the Mid-Latitude F2-Region

Abstract

In this chapter we shall deal with the regular variations of the parameters of the F2-layer of the ionosphere, which are typical in magnetically quiet conditions. These include: the annual variations of frequencies, f ₀ F2, at noon; and the seasonal and the December anomalies, the dependence of the annual variation of f ₀ F2 on the latitude and on the solar activity level. All these problems are primarily connected with the annual variations in the F2-region. Diurnal variations are also regular. We shall discuss the role played by the individual processes in the formation of the F2-region in daytime and at night. In particular, we shall concentrate on the problem of formation of the nighttime F2-layer and shall discuss the phenomenon of the nightly increase of electron concentration, which is observed in winter.