Local Time Dependence of High-Latitude Pc5 Wave Activity Driven by Interplanetary Shocks and Foreshock Transients, Using a New ULF Index

We present a study of ground-based Pc5 ultra-low frequency (ULF) wave response to over 400 interplanetary (IP) shocks and 18 foreshock transients. We investigated the local time dependence of magnetospheric Pc5 wave power generated by IP shocks and foreshock transients and whether this dependence is related to the impact angle of IP shocks and impact point of foreshock transients. To study this, we created a new magnetic local time dependent high-latitude Pc5 ULF wave index using magnetic field measurements from high latitude magnetometers obtained from SuperMAG. Our findings indicate that the impact angle of an IP shock does not determine the location of the peak Pc5 power. However, we find that frontal shocks drive stronger wave power than inclined shocks. Shock speed and dynamic pressure ratio correlate moderately with the peak Pc5 power. During 61% of the studied foreshock transients, we observe a clear Pc5 response, that is, the wave power increased significantly. The distribution of Pc5 power is consistent with the propagation direction of the transients. The results suggest that the size of the foreshock transient and the solar wind speed may affect the observed Pc5 wave response. Although the Pc5 response to IP shocks and foreshock transients differ, foreshock transients can drive Pc5 wave power comparable to IP shocks.