Wavelet Analysis on Solar Wind Parameters and Geomagnetic Indices |
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Authors: | C Katsavrias P Preka-Papadema X Moussas |
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Institution: | 1. Section of Astrophysics, Astronomy and Mechanics, Department of Physics, University of Athens, Panepistimiopolis Zografos (Athens), 15783, Greece
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Abstract: | 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 , β, Alfvén 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?–?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. |
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