TY JOUR TI Diurnal variations in characteristics of sporadic layer Eₛ over Irkutsk KW sporadic layer KW diurnal variations KW occurrence frequency KW height KW semidiurnal tides JO Solar-Terrestrial Physics AU Voronova, E.Y. AU Ratovsky, K.G. PY 2025 IS 11 PB Institute of Solar-Terrestrial Physics SB RAS