Determining dynamic parameters of different-scale ionospheric irregularities over northern Siberia

In 1995-1996, observations were carried out at Norilsk (geomagnetic latitud e and longitude 64.2 degrees N and 160.4 degrees E) to determine dynamic pa rameters of irregularities in the high-latitude ionosphere. The short-basel ine spaced-receiver method that has been implemented at the ionospheric fac ility of the Norilsk Integrated Magnetic-Ionospheric Station, provides a me ans of simultaneously measuring parameters of small-scale irregularities (s patial scale of 3-5 km) by the Similar-Fading Method (SFM), as well as of m edium-scale irregularities (time scale of 10-30 min, spatial scale of hundr eds of kilometres) by the Statistical Angle-of-arrival and Doppler Method ( SADM). About 20 h of the observational data for the F2-layer under quiet ge omagnetic conditions (K-p < 3), 20 h under disturbed conditions (K-p greate r than or equal to 3) and about 15 h for the sporadic E-layer (K-p approxim ate to 3) were processed. It has been found that the propagation directions and velocities of different-scale irregularities do not coincide. Small-sc ale irregularities of the FZ-layer travel predominantly eastward or westwar d. The velocity of the F2-layer irregularities is about 100 m/s, and under disturbed conditions it is up to 200-250 m/s. Small-scale irregularities of the sporadic E-layer travel mostly in the northward direction. It is confi rmed that the E-s-layer is haracterised by high velocities of the irregular ities (as high as 1000 m/s). Medium-scale irregularities with periods in th e range of 10-30 min travel mostly in a southward direction with velocities of 20-40 m/s. (C) 2000 Elsevier Science Ltd. All rights reserved.