SPECTRAL STRUCTURE OF THE NORTH ATLANTIC OSCILLATION

E. A. Rybak and O. O. Rybak

Year-to-year variations of the intensity and phase of the North Atlantic Oscillation (NAO) play a key role in the formation of weather conditions over Europe and the Mediterranean basin. The NAO indices calculated from data of different meteorological stations in general equally describe the frequency-time structure of its variability. The non-evolution autoregression spectrum of the NAO has a bimodal structure. Noise filtration and subsequent reconstruction of the series makes it possible to localize spectral peaks. Wavelet analysis of the series of monthly mean and annual mean values of the NAO index is indicative of a alternation of regimes with different prevailing types of interannual variability.