IONOSPHERIC RESPONSE TO VARIABLE ELECTRIC-FIELDS IN SMALL-SCALE AURORAL STRUCTURES

High time and space resolution optical and radar measurements have rev ealed the influence of electric fields on E-region electron density pr ofiles in small-scale auroral structures. Large electric fields are pr esent adjacent to auroral filaments produced by monoenergetic electron fluxes. The ionisation profiles measured within and beside the aurora l filaments show the effects of plasma convection due to electric fiel ds as well as the consequences of the response time to large and dynam ic fluxes of energetic electrons. Without high-resolution optical meas urements, the interpretation of the radar data is limited.