<i>AE</i> index variability during corotating fast solar wind streams

Abstract

We examine the AE index variability while 12 corotating fast solar wind streams pass the Earth during the ascending phase of the ongoing solar activity cycle. We apply the Discrete Fourier Transform analysis to the associated interplanetary magnetic field ( B ) data and AE time series with ∼1 min resolution. Results show noticeable periodicities in the 1–10 hour range. Moreover, the B and AE periodicities in each event are well correlated. For this reason a direct relationship between interplanetary Alfvénic waves and AE oscillations is proposed while those streams pass the Earth.