Abstract.We propose and test a method of analyzing ionograms of vertical sounding, which is based on detecting deviations of the shape of an ionogram from its regular (averaged) shape. We interpret these deviations in terms of reflection from electron density irregularities at heights corresponding to the effective height. We examine the irregularities thus discovered within the framework of a model of a localized uniformly moving irregularity, and determine their characteristic parameters: effective heights and observed vertical velocities. We analyze selected experimental data for three seasons (spring, winter, autumn) obtained nearby Irkutsk with the ISTP SB RAS fast chirp ionosonde in 2013-2015.The analysis of six days of observations conducted in these seasons has shown that in the observed vertical drift of the irregularities there are two characteristic distributions: wide velocity distribution with nearly 0 m/s mean and with standard deviation of ~250 m/s and narrow distribution with nearly -160 m/s mean. The analysis has demonstrated the effectiveness of the proposed algorithm for the automatic analysis of vertical sounding data with high repetition rate.

We present a technique of MUF real-time forecast based on time extrapolation for maximum observed frequencies smoothed over a long-term forecast along a given path. We have validated the technique of fitting current data from the long-term forecast, using the OPEMI model, transmission curve method for short paths, and method of normal waves for long paths (over 2000 km). This technique has been tested using data obtained at the chirp sounding network of ISTP SB RAS during periods of strong and weak solar activity. The quality of the forecast has been found to significantly improve in comparison to the long-term forecast, with advance intervals of real-time forecast from 15 to 30 min. The sessions, in which the real-time forecast error is less than 10 % for 15-min advance interval, comprise from 67 to 96 % of all sessions depending on season and radio path orientation.

We propose and test a method of analyzing ionograms of vertical ionospheric sounding, which is based on detecting deviations of the shape of an ionogram from its regular (averaged) shape. We interpret these deviations in terms of reflection from the electron density irregularities at heights corresponding to the effective height. We examine the irregularities thus discovered within the framework of a model of a localized uniformly moving irregularity, and determine their characteristic parameters: effective heights and observed vertical velocities. We analyze selected experimental data for three seasons (spring, winter, autumn) obtained nearby Irkutsk with a fast chirp ionosonde of ISTP SB RAS in 2013–2015. The analysis of six days of observations conducted in these seasons has shown that in the observed vertical drift of the irregularities there are two characteristic distributions: wide velocity distribution with nearly 0 m/s mean and with standard deviation of ~250 m/s and narrow distribution with nearly –160 m/s mean. The analysis has demonstrated the effectiveness of the proposed algorithm for the automatic analysis of vertical sounding data with high repetition rate.

We present a technique of MUF real-time forecast based on time extrapolation for maximum observed frequencies smoothed over a long-term forecast along a given path. We have validated the technique of fitting current data from the long-term forecast, using the OPEMI model, transmission curve method for short paths, and method of normal waves for long paths (over 2000 km). This technique has been tested using data obtained at the chirp sounding network of ISTP SB RAS during periods of strong and weak solar activity. The quality of the forecast has been found to significantly improve in comparison to the long-term forecast, with advance intervals of real-time forecast from 15 to 30 min. The sessions, in which the real-time forecast error is less than 10 % for 15-min advance interval, comprise from 67 to 96 % of all sessions depending on season and radio path orientation.