Auroral hiss: a review

A review of auroral hiss emissions observed at ground-based stations and in the magnetosphere is presented. Different approaches to modelling of these emissions are discussed. It is pointed out that the most likely energy source of these emissions lies in the electrons at energies below 100 eV precipitating to the auroral ionosphere. Initially, the waves are generated due to incoherent Cerenkov radiation and they are then amplified due to beam instability on the Cerenkov resonance. Different dynamic spectra of auroral hiss emissions are interpreted in terms of wave propagation from a localized source.