EXPERIMENTAL IONOSPHERIC TOMOGRAPHY WITH IONOSONDE INPUT AND EISCAT VERIFICATION

Results are presented of tomographic images of ionospheric electron de nsity obtained from experimental measurements of total electron conten t at a linear chain of stations. Comparison with independent measureme nts made using a special scan of the EISCAT incoherent scatter radar s how broad agreement except under extreme ionospheric conditions. The l arge-scale horizontal features of the electron density are replicated well in the tomographic image. The vertical profile is dependent on th e ionospheric model used to create the background ionosphere formed as an initial condition in the reconstruction process. The inclusion of additional independent information in the form of the electron density and height of the layer peak obtained from ionosondes, has been incor porated into the imaging procedure. The resultant tomographic images s how improved agreement with the EISCAT measurements in the vicinity of the layer maximum.