Ionospheric troughs in Antarctica

We report here the first observations of the dynamics of both the mid-latitude and high-latitude troughs made by the Advanced Ionospheric Sounder (AIS) at Halley Station, Antarctica (76° S, 27° W; invariant lat. 61°). This experiment is part of a major international project1 to study the sub-auroral ionosphere and its associations with the magnetosphere. Our analysis provides an accurate quantitative description of the latitudinal movements of these features and the first results delineating the orientation of the poleward edge of the mid-latitude trough. These results show that the AIS has a much greater potential for monitoring large scale ionospheric structures and for tracking their motions than more conventional radio wave experiments.