A comparison of methods used for obtaining electron content from satellite observations

Measurements of the effects of the ionosphere on the polarization and the Doppler shift of radio transmissions from earth satellites permit the electron content of the ionosphere to be calculated. Thirty‐five passages of Transit 2A have been analyzed in a variety of ways to estimate the accuracy of the several methods. The most accurate method is a hybrid analysis using both Faraday and Doppler data simultaneously. Methods based on the rate of polarization rotation, on the number of rotations between two times, and on best‐fitting polynomials to either the Faraday or the Doppler data are compared and their errors estimated.