Manifestations of geomagnetic activity on a transauroral HF radio path

This paper considers the results of an experiment conducted in May 2002 on the radio path St. Petersburg-Spitsbergen with a length of D = 2150 km and equipped with instrumentation for oblique ionospheric sounding (OIS). The features of OIS ionograms at various degrees of magnetic activity are revealed, and a comparison of these ionograms with the vertical sounding (VS) data at the Sodankyla observatory (Finland) is performed. This observatory is located near the reflection point of the path in question. In order to estimate the auroral absorption, riometer data from the Sodankyla observatory were included in the analysis of the OIS and VS ionograms. The merits of the OIS method as a diagnostic tool of ionospheroic plasma in comparison with VS at high latitudes are demonstrated. These merits are mainly formulated for magnetically disturbed periods: in the presence of B events (black-outs), anomalous sporadic Es formations, and a series of other events.