Electron precipitation and ionospheric radio absorption in the auroral zones

Auroral absorption, measured with riometers at various stations, has been compared with the fluxes of energetic particles detected simultaneously by a satellite passing overhead. The absorption and the particle flux are found to be correlated, the relation depending on the time of day. The observed relationship is discussed in the light of computations of the absorption, based on the rates of ion production previously given by Rees and on reasonable atmospheric models. A case is presented for more prolonged comparisons of this kind, the combination of a polar orbit with ground-based observations at the South Pole station being particularly fruitful in this type of experiment.