Summary plot of the reverse SIR shock on 2008 March 9. (a)–(c) Magnitude ﹩| B| ﹩, azimuthal angle ϕ_B, and elevation angle θ_B of IMF in 1 s resolution, (d) solar wind proton bulk velocity in 1 minute resolution. (e)–(g) Count rate per minute of ∼10–40 keV/nuc He²⁺, ∼8–20 keV/nuc He⁺, and ∼10–40 keV/nuc H⁺. The right blue line indicates the shock arrival at ∼1950 UT, and the bold colored lines mark the boundaries of the four periods analyzed in this study.