FIRI: A semiempirical model of the lower ionosphere

An empirical model of the lower, nonauroral ionosphere is presented which is exclusively based on radio wave propagation data from rocket soundings. The very limited number of available profiles provides an empirical correction to a simple theoretical model. This analytical correction, which can be of a very low mathematical order, is determined individually for each pressure surface. An inclusion of this model in tabulated form into the international reference ionosphere (IRI) is foreseen, and electron density profiles for the conditions required by the user can be obtained by interpolation.