The nighttime winter lower ionosphere during January-February 1982

Features characterizing the nighttime winter lower ionosphere in January-February 1982 were investigated at the Volgograd station using rocket measurements of electron density, temperature, wind, water-vapor concentration, as well as ground measurements of radio-wave absorption in the ionosphere. It is shown that, despite the absence of major stratospheric warmings, the variability of ionospheric parameters was considerable in both daytime and nighttime. In some periods, variations of N sub e and L were explicitly determined by fluctuations of the level of solar and geomagnetic activity, while such a relationship was absent in other periods. Maximum values of N sub e in January were recorded in periods of maximum shift from the cyclonic vortex pole. A significant variability of the form of nighttime N sub e(h) profiles, increasing with height, was noted.