Influence of an inhomogeneous structure of the high-latitude ionosphere on the long-distance propagation of high-frequency radio waves

Abstract

We present the results of experimental studies of the features of long-distance propagation of high-frequency radio waves on the large-extent subauroral Magadan–Rostov-on-Don and midlatitude Khabarovsk–Rostov-on-Don and Irkutsk–Rostov-on-Don paths, which were obtained using the ionosonde-finder with a chirp output signal. Anomalous (lateral) signals with delays of about 1–2 ms with respect to a direct signal, which arrive from the azimuths 10°–20°, are observed on the Magadan–Rostov-on-Don path. The lateral signals were observed in the morning and antemeridian hours in the time interval 08:00–10:40 MSK. In the evening and night hours, the lateral signals were not observed. During magnetic activity, the amplitude of the lateral signals was greater than that observed prior to a magnetic storm by 5–10 dB. Location of the ionospheric-perturbation regions responsible for the appearance of the lateral signals was determined as φgeogr ≈ 69°–71°N (φmagn ≈ 65°–66°N), and λ ≈ 51°–58°E. The mechanisms of the lateral-signal propagation due to lateral refraction of radio waves on patches with enhanced electron number density and due to scattering of radio waves from small-scale irregularities are considered.