Analysis of magnetometer data using wavelet transforms

Abstract

Geomagnetic field–line resonances may be identified via the use of cross–phase analysis of data from two closely spaced meridional ground–based magnetometer stations. It has been demonstrated that preprocessing of the data using a wavelet–based filter, chosen with regard to the variance of coefficients of the wavelet components, can be used to remove both low–frequency trend and large amplitude, localized structures, thus facilitating the selection of the eigenfrequency. We demonstrate that the dependence of the variance of coefficients on the wavelet level during a geomagnetic storm event is characteristically different from that obtained from data on a day associated with quiet geomagnetic activity. This suggests that the spectral nature of magnetic disturbances excited in the magnetosphere is dependent upon the level of geomagnetic activity.