Advances in ionospheric propagation modelling at high-latitudes

Many services rely on the output of propagation planning tools to predict the future state of the ionosphere and the availability of suitable communications channels. While this approach is adequate for services operating at high-latitudes during quiet ionospheric conditions it is insufficient to deal with a disturbed ionosphere. This paper presents the results of empirical modelling of the changes that occur in the D- and E-regions of the ionosphere following the onset of disturbed conditions as defined by the occurrence of a storm sudden commencement.