High-latitude ionosphere structure in dayside sector on ground-based and satellite measurements

We report electron density measurements from satellite Cosmos-900 the presence of high-latitude dayside troughs. The trough minima near noon are localized at 70-74 degrees invariant latitude during indisturbed periods and at 60-70 degrees invariant latitude during disturbed periods. The localization and dynamics of equatorial boundary of dayside polar cusp by oblique sounding of F-region from ground-based stations and by simultaneous measurements of precipitating particles from satellite are revealed. A comparison of statistical data of dayside troughs and reflections from dayside cusp shows that a trough minimum near noon is localized by 3-4 degrees equatorward of the cusp. The obtained results are discussed. (C) 1997 COSPAR. Published by Elsevier Science Ltd.