Energy spectra of incident electrons from auroral ionisation profiles

The production of ionospheric ionisation at night by auroral electrons and its height dependence are discussed. It is found that the altitude dependence of the effective recombination coefficient αsub(e) of the ions involved is of great importance in determining the ionisation profile produced by a given incident electron spectrum. Electron density profiles obtained in the auroral zone at night are examined for several nights during conditions of diffuse aurora. The incident electron spectra are computed from these measurements. (author)