The P2 (4-8 mHz) and P5 (32-64 mHz) events occurred more
frequently at high solar wind speeds. This is especially clear for the
P5 events. The occurrence rates for the P3 (8-16 mHz) and
P4 (16-32 mHz) events maximize when Vp = 400-450 km/s and
Vp = 500-550 km/s, respectively, but neither case has a high
normalized occurrence rate when the solar wind speed is higher
than 550 km/s.
Figure 9. Normalized occurrence rates for events at different solar wind speeds.