Fast Ionospheric Dynamics during a Substorm from Vertical and Oblique Sounding Data

Abstract

Synchronous studies have been conducted on the high-latitude ionosonde at Sodankyulä station and the low-latitude ionosonde in Cyprus Island, as well as on two radio paths (the Sodankyulä–Gor’kovskaya subauroral and Cyprus–Gor’kovskaya midlatitude paths) during the intense substorm of February 14, 2011. Fast processes (within 5–10 min) have been identified according to vertical sounding at Sodankyulä station: sporadic Es layers with an inclined track, multilayer tracks in Es layers, anomalous spreadF, well-expressed layers in diffuse F formations, rapid changes in the peak observed frequencies in the Es layer, and multijump Es reflections of signals. During the substorm, the sporadic Es layers and diffusion in the ionospheric F2 layer are the most stable. The data from vertical sounding at Sodankyulä station and oblique sounding on the Sodankyulä–Gor’kovskaya track have been found to agree qualitatively. The distance between Sodankyulä station and the reflection point of the Sodankyulä–Gor’kovskaya path is 400 km in the southern direction. Thus, the ionospheric processes during the substorm are qualitatively close, within 400 km. However, there is a difference between the vertical and oblique sounding data and the data from oblique sounding on the Gor’kovskaya–Cyprus track with a reflection point near the city of Chișinău.