Tomographic imaging of electron density in the auroral ionosphere

Computerised tomography involves the measurement of the line integral of a parameter along many intersecting ray paths with inversion of the resultant data to give a two-dimensional image of the parameter. In ionospheric tomography, the total electron content is measured with the reconstruction yielding electron density in a cross-section through the ionosphere. The paper reports results from a campaign of experimental observations made in Scandinavia in which the tomographic images of electron density have been compared with measurements obtained from a specially designed scan of the EISCAT radar. The `ground truth´ observations by the radar provide verification of the tomographic technique