Mapping electron content near the main trough

Applications involving radio waves propagating through the ionosphere are subject to errors due to the effects of the medium, the electron content along the propagation path often being a key parameter. At high latitudes, steep gradients in electron content in the vicinity of the ionospheric trough are of particular importance. The sub-auroral region containing the trough is also characterised by the boundary between the relatively homogeneous mid-latitude ionosphere and the irregular auroral ionosphere. The small-scale irregularities are responsible for the scintillation of radio signals and so are also of considerable interest to propagation applications. The authors discuss the mapping of electron content and scintillation in the sub-auroral region over northern Europe. The authors describe the experiment which made use of signals transmitted from the constellation of seven NNSS satellites in near-circular polar orbits at heights of 1100 km. They describe how the measurements have been combined to give detailed information about electron content and irregularity behaviour in the vicinity of the trough as a function of both latitude and time