Panels (a)–(b) show the negative real (−ω_r) and imaginary (ω_i) parts of the wave frequency (normalized to the proton cyclotron frequency ω_p) vs. wavenumber for upstream low-frequency A/IC waves for the IP shock in Figure 5. Solutions use the fitted VDF from Figure 6 as input to a linear dispersion solver. Orange lines show Doppler-shift-derived dispersions based on the observed wave frequency near ω_p. Panels (c)–(d) show the same analysis for downstream A/IC waves.