Source (red) and advective (blue) terms at a fixed r = 1.5r_p and θ = 0.2, plotted over azimuthal angle ϕ. From top to bottom, we plot these terms for ρ (in units of Ω_pρ_0,p), T_g (Ω_pT_g,0,p), υ_r, υ_θ, and υ_ϕ (Ω_pc_s,iso,p), where the p subscript indicates quantities taken at the planet location in the initial condition. A thin dashed gray line passes through the azimuthal peak of the density spiral, showing the significant offset between terms driving spiral perturbations in each quantity.