Techniques to obtain Faraday electron content from polarimeter data at low and middle latitudes

The technique used at present to obtain Faraday electron content from polarimeter ground measurements of beacon signals is briefly reviewed and its basic assumptions are pointed out. A new alternative method is described. This method obviates the knowledge of the orientation of the transmitted electrical field and removes the so-called ambiguity problem, and it may be useful in the case of interrupted polarimeter records. It makes use of electron density profiles obtained from an ionosonde located near the subionospheric point. Numerical comparisons of this method with the conventional one give good agreement. The relative advantages of both techniques are pointed out.