Illustration how O⁺ daily variabilities are derived. Top main panel: 5-min solar-wind speeds v_sw(t) (top, left) and expectation values ) (top, right) are used to construct a time series of expected counts (blue, bottom). Together with the time series of observed counts (red, bottom), observed and expected daily values can be derived. Bottom main panel: time series of observed (red) and expected (blue) daily counts (top). Error bars denote the uncertainty due to counting statistic. Finally the time series of the resulting daily variability is displayed (bottom).