Relationship of Oscillating Aurora to Substorms and Magnetic Field Line Resonances

Abstract. Oscillating auroral phenomenon are frequently associated with magnetospheric substorms. We present an analysis of photometer data which displays such oscillations in luminosity. We use data from the Gillam station in the CANOPUS array for April 1, 2000. Clear pulsations are observed at 2.2 mHz. The latitudinal distribution of the pulsations indicates that the luminosity variations, caused by precipitating electrons and protons, are modulated by large scale global compressional modes [field line resonances]. The proton and electron aurora were found to oscillate essentially out of phase. As well, the variation of phase across the peak in the luminosity resonance follows the pattern expected for the coupling of resonant Alfvèn modes by normal compressional modes in the magnetotail