Interpretation of ionospheric F-region structures in the vicinity of ionisation troughs observed by satellite radio tomography

Tomographic images of the spatial distribution of electron density in the i onospheric F-region are presented from the Russian-American Tomography Expe riment (RATE) in November 1993 as well as from campaigns carried out in nor thern Scandinavia in November 1995 and in Russia in April 1990. The reconst ructions selected display the ionisation troughs above the tomographic chai ns of receivers during geomagnetically quiet and disturbed periods. Two mat hematical models of the high-latitude ionosphere developed in the Polar Geo physical Institute have been applied for interpretation of the observed tom ographic images.