RAPID AURORAL PULSATIONS WITH FREQUENCIES OF 0.05-40Hz

An image intensifier-television system equipped with an auroral photometer has been installed at Syowa Station to observe the auroral rapid luminosity fluctuations. In addition to the large amplitude auroral fluctuations observed mainly at the time of onset of an auroral substorm, several different spectral types of pulsating auroras are found in the active auroras in the frequency range from 0.05 to 40Hz, the principle dominant spectral frequencies being at about 0.08,1,10 and 25Hz. Study of the association between auroral luminosity and magnetic pulsations shows that correlations are good in case of 0.08Hz fluctuations, while poor in cases of the 1,10 and 25Hz rapid fluctuations