Sporadic ES Layers at High Latitudes During a Magnetic Storm of March 17, 2015 According to the Vertical and Oblique Ionospheric Sounding Data

Abstract

We consider the behavior of the parameters of the ionospheric E_s layers according to the vertical sounding at the Sodankylä observatory and oblique sounding at the Lovozero (Murmansk region)—Gor’kovskaya station (Leningrad region) path during a superstorm of March 17, 2015. Temporal and spatial behavior of these parameters is compared. It was found that the storm significantly distorted the normal course of variations of the sporadic E_s layer characteristics. Specific behavior of the layers during a storm at points separated by about 300 km was detected. With the help of ray tracing calculations using the IRI model, oblique sounding ionograms were constructed for the radio path analyzed. Primary attention is given to the maximum usable frequency of the F₂ layer—MUF-F₂. Additionally, for the disturbed conditions where there is only a high-power E_s layer on the experimental ionograms, the values of MUF-E_s and the ratio K =MUF-E_s/f_oE_s for various cutoff frequencies f_oE_s of the E_s layer and its altitudes \( {h}_{E_s} \) are calculated within the framework of the well-known approximations. Calculations for the case of weak disturbance and semitransparent E_s layers are carried out with the IRI model adapted to the current diagnostics parameters. It was found that the calculated and experimental values of MUF-F₂ are close to each other or coincide, while this cannot be said about MUF-E_s. The calculated and experimental values of MUF-E_s can be matched in the model of mirror reflection from a flat layer for intense layers and the model of the E layer for thick E_s layers of low intensity.