EISCAT (European incoherent scatter radar) electron density studies

Abstract : The study of F-region electron density irregularities has continued and further runs of the Special Program have been scheduled to coincide with overpasses of the HILAT satellite. Programming improvements have led to more effective analysis of the data from both EISCAT and HILAT observations. Major variations in electrons in electron content are shown to be related to well defined enhancements of electron density. Typical periods range between 35 and 200 seconds, imply spatial structures of 12 to 70 km. These variations would have significant effects on transionospheric radio propagation. Preliminary comparisons have been made between EISCAT and HILAT measurements of total electron content. A significant difference between the measurements is observed, the HILAT observations being 2.2 times larger than those derived from EISCAT. The HILAT measurements from the December 1985 appear to be too large. A brief description is given of the first run of the Special Program on the VHF radar. Keywords: Incoherent scatter radar; Plasma structure; Ionospheric F region; Auroral Zone electron content.