The wavelet analysis as applied to the study of geomagnetic disturbances

A wavelet analysis of the geomagnetic. disturbances observed during geomagnetic storms has been performed. Spectral estimates of the geomagnetic disturbance field have been derived from three types of experimental data: Dst variations, ground-based series of observations at magnetic observatories, and MAGSAT observations. A wavelet analysis of satellite data has indicated that two classes of different-scale spatial irregularities can be distinguished in the meridian sections of the ring current system. This division is stable for virtually the entire storm period considered. The ring current is pronouncedly asymmetric at its initial stage of growth, and a structure symmetric in the dawn-dusk plane takes shape only after stabilization of the current system. The small-scale irregularities become considerably larger and more complicated during this period. A wavelet analysis of ground-based observations of the auroral and polar disturbances has indicated that these disturbances have a complicated character: several large-scale irregularities, which reflect a smooth portion of the positive and negative bays, and small-scale irregularities, which are sometimes very intense and have a complex frequency-time structure are distinguished.