On a characteristic point at the base of the F 2 layer

Abstract

The behaviour of the point of inflection of the electron density profile below the peak of the F 2 layer, considered as a “characteristic point”, is analyzed using a large number of profiles calculated from composite ionograms obtained at low and middle latitudes southern hemisphere stations. The diurnal, seasonal and latitudinal variations of the electron density, height and height gradient at that point are discussed. It is also shown that these parameters are linearly correlated with the electron density and height of the peak of the F 2 layer. Linear correlation functions between the coordinates of the point and the values of f 0F 2 and M(3000)F 2 read in the ionograms have been found. These functions can be used to calculate the electron density, height and height gradient of the “characteristic point” in the electron density profile, from routinely scaled ionospheric parameters.