Flayer scintillations and the aurora

Abstract

Defense Meteorological Satellite Program photographs of the aurora are correlated with the scintillation of radio signals from both low-altitude and synchronous satellites. Measurements from several stations ranging from subauroral to auroral locations show that the irregularities producing the scintillation exist both equatorward and poleward of the optical aurora. The scintillations are seen to peak when the satellite path is through the aurora, the values falling off with distance from the aurora. Factors which allow for interpretation of the data under two different irregularity formations are applied to the median curves of the variation of scintillation with distance from the aurora for each station. The dominating irregularities for meter wavelength scintillation appear to be elongated and elliptical. To illustrate the extension of the F layer irregularities equatorward of the optical aurora, the magnetic storm of April 18, 1974, is examined. Different mechanisms for the irregularity production, such as heat flow and low-energy electron precipitation, are suggested.