Structure analysis of geosynchronous substorm oscillations

Substorm events as observed by geostationary satellites are accompanied by large amplitude transient low frequency oscillations on the electric and magnetic field components. The "short" period oscillations (similar to 40 - 100 s) have been interpreted as standing waves confined to the thin current sheet which develops prior to the substorm onset. The signatures of these oscillations depend in particular on the position of the spacecraft relative to the current sheet, and on a, number of additional physical parameters related both to the current sheet and the waves. Changes in these parameters with time give rise to both temporal and spatial effects. Synthetic signal analysis using wavelets can be employed to investigate signatures of oscillations under different physical conditions, and it can be a useful diagnostic tool in interpreting the nature of complicated real signals in a reasonably consistent manner. Wavelet analysis has been used to illustrate the signatures of oscillations recorded at different s/c positions, as would be the situation with multi-satellite systems.