Comparative ionospheric and plasmaspheric electron contents from three world regions

Abstract

THE radio beacon experiment1–3 aboard the geostationary Applied Technology Satellite ATS-6 enables the determination of total electron content (TEC) to be made by two independent methods. The first—the Faraday polarisation rotation technique—has been widely used in obtaining TEC data. Faraday rotation is dependent on the Earth's magnetic field, and, since its magnitude is heavily weighted near the Earth, it is considered to provide integrated electron content values for altitudes below ∼1,500 km. The second—the dispersive-group-delay technique, in which the phase of the modulation envelope between a carrier and its sideband is compared at two frequencies—is independent of the Earth's magnetic field and thus yields the integrated electron content between the observer and the satellite signal source. The Faraday content, NF, and the dispersive-group-delay content, NT, therefore, yield the TEC up to ∼1,500 km and geostationary altitudes, respectively. The difference between NT and NF yields the content above ∼1,500 km, which is referred to as the plasmaspheric content, Np.