Influence of the b solar wind parameter on statistical characteristics of the Ap index in the solar activity cycle

We have studied the effect of the β solar wind parameter (equal to the ratio of the plasma pressure to the magnetic pressure) on statistical characteristics of the A p index reflecting the triggering behavior of the activity of Earth’s magnetosphere. The trigger effect of the dynamics of magnetospheric activity consists in the abrupt transition from the periodic mode to the chaotic mode in the solar activity cycle. It is shown that cumulative amplitude distribution functions and power spectra of the A p index of both the periodic and chaotic modes are well approximated by power and exponential functions respectively. At the same time, the indices of power functions and the indices characterizing the slope of the A p index spectrum differ significantly in magnitude for the periodic and chaotic modes. We have found that A p nonlinearly depends on β for both the modes of magnetospheric dynamics. The maximum of the A p index amplitude for periodic modes is observed when β>1; and for chaotic ones, when β