The height properties of the O- and Z-modes interference in sporadic E layer traces

Ionosphere reflectivity investigation using ionosonde is important in the study of inhomogeneous layers fine structure. For these purposes, interference beatings was studied. Therefore, in 70–80-ies of the last century, much attention was focused on the polarization beatings and mode coupling of the Es-layer (see for example [Chessell et al., 1973; Jalonen, 1981; Turunen et.al, 1980]). Considered that if where are the steep gradient of the electron density, then the energy coupling from the O-mode to the X-mode can be. It is also called the Z-mode, which is reflected in the higher height and it again becomes as O-mode. Such beatings in the mid-latitude Es-layer traces are difficult to observe in ionograms, the pattern becomes clearer only when using the A-maps. Which allowed to find and to establish the properties of O- and Z-modes beatings namely the the long dips observed in the Es-layer traces amplitude (comparing with the beatings steps of the O- and X-modes [Akchurin and Usupov, 2011]). In the A-maps these beatings resemble the “rings” and they are located in the frequency range above ƒoE to ƒoEs−ƒH/2. Such long amplitude dips have very small difference in reflection heights between the O- and Z- modes less than 200m (because it is the steep gradient conditions for the coupling and the Z-mode reflection do not differ by more than 200 meters).