Wavelet Analysis on Solar Wind Parameters and Geomagnetic Indices

The geomagnetic activity is the result of the solar wind-magnetosphere interaction. It varies following the basic 11-year solar cycle; yet shorter time-scale variations appear intermittently. We study the quasi-periodic behavior of the characteristics of solar wind (speed, temperature, pressure, density) and the interplanetary magnetic field (B (x) , B (y) , B (z) , beta, Alfv,n Mach number) and the variations of the geomagnetic activity indices (D (ST), AE, A (p) and K (p)). In the analysis of the corresponding 14 time series, which span four solar cycles (1966 -aEuro parts per thousand 2010), we use both a wavelet expansion and the Lomb/Scargle periodograms. Our results verify intermittent periodicities in our time-series data, which correspond to already known solar activity variations on timescales shorter than the sunspot cycle; some of these are shared between the solar wind parameters and geomagnetic indices.