The determination of ionospheric electron content and distribution from satellite observations: 1. Theory of the analysis

Abstract

Two techniques are described which permit the integral of the electron density up to the satellite height to be deduced from the satellite radio transmissions. One method is based on the rate of polarization rotation due to the Faraday effect. The other method depends on a measurement of the total angle of polarization rotation at the time of closest approach of the satellite. If useful results are to be obtained, a number of corrections to assumptions made in the simplified analysis are necessary to account for path splitting between the two magneto-ionic components, error in the ‘high-frequency approximation,’ refraction, and satellite-antenna motion. Owing to the slow rotation of the satellite perigee position, the height of the passage at any given latitude varies. Variations of the integrated electron density with height can then be related to the electron-density profile. The results of the observations of Sputnik III radio signals in an 8-month period are included in part 2.