Wavelet Analyses of Geomagnetic Data regarding Major Geomagnetic Disturbances

The purpose of this study was to analyze the associated spectrum of geomagnetic field, frequencies intensity and the time of occurrence. We calculated the variation of the correlation coefficients, with mobile windows of various sizes, for the recorded magnetic components at different latitudes and latitudes. The observatories we included in our study are USA (Surlari), HON (Honolulu), SBA (Scott Base), KAK (Kakioka), THY (Tihany), UPS (Uppsala), WNG (Wingst) and Yellowknife (YKC). We used the data of these observatories from International Real-time Magnetic Observatory Network (INTERMAGNET) for the geomagnetic storm from October 28-31, 2003. We have used for this purpose a series of filtering algorithms, spectral analysis and wavelet with different mother functions at different levels. In the paper, we show the Fourier and wavelet analysis of geomagnetic data recorded at different observatories regarding geomagnetic storms. Fourier analysis hightlights predominant frequencies of magnetic field components. Wavelet analysis provides information about the frequency ranges of magnetic fields, which contain long time intervals for medium frequency information and short time intervals for highlight frequencies, details of the analyzed signals. Also, the wavelet analysis allows us to decompose geomagnetic signals in different waves. The analyses presented are significant for the studies of the geomagnetic storm. The data for the next days after the storm showed a mitigation of the perturbations and a transition to quiet days of the geomagnetic field.