ИСТИНА

The lower polar ionosphere researches are carried out on the modified measuring complex of the observatory Tumanny (69.0N, 35.7E) since 1999. Investigations of dynamic processes caused by movements of neutral atmosphere, variations of electron density are implemented and analysis of statistical and frequency characteristics of scattered signals are carried out. Calculations of the electron concentration were carried out by technique of differential absorption. Analysis of the date has shown that there are regions of lower electron density at heights near the mesopause with life times from one minute till several hours. Radioechoes from the regions had enhanced intensities. Layers of electron concentration irregularities with scales more than 100 m at heights from 70 till 99 km were detected by the technique of spaced receiving of scattered signals. During the solar eclipse of 1999 August 11 during short time an enhanced intensity of a radioecho was detected at heights near the mesopause.