Abstract:
Black auroras are recognised as spatially well-defined regions of reduced optical emissions within a much brighter, quasi-uniform diffuse auroral background. The energy of the precipitating electrons is reduced within the black aurora compared to the surrounding diffuse aurora. They are usually seen drifting eastward during the substorm recovery phase. Several theories have been proposed to explain the decrease in electron energy and flux in this region, but the underlying mechanism is as yet unknown. The black aurora phenomenon has been studied by both optical and radar methods, using the EISCAT incoherent scattar radar in Tromso, Norway in conjunction with multi-wavelength cameras. Results derived from optical and radar methods are presented here, which shows characteristic energies, as well as precipitating particle energy spectra, for both inside and outside the black aurora. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
