The effects of receiver location in two-station experimental ionospheric tomography

Experimental results are presented of the imaging of a narrow field-aligned trough in electron density with an associated boundary blob using the techniques of ionospheric tomography, with verification by means of independent measurements from the EISCAT radar. An authentic image is still obtained when observations from only two receiving sites are used if the structure is in the vicinity of the stations. However, the image quality is degraded when the feature, with its strong horizontal gradients, is far from overhead. The results are of importance to the application of ionospheric tomography to the study of spatial structures in electron density over remote and inhospitable regions like the polar caps where the location of ground stations is restricted.