Seasonal evolution of frost on 30° south-facing slopes (blue), flat surfaces (red), and 30° north-facing slopes (black) on Pluto, shown for latitudes 40°N (A, B), 20°N (C, D), 0°N (E, F), and 10°S (G, H). For each latitude, N₂ frost thickness is shown in the left panels, and CH₄ frost thickness in the right panels. The dashed gray line marks the date of the New Horizons flyby. For cases with perennial accumulations, thickness values have been rescaled for clarity. The frost thicknesses shown here are zonal averages of the model outputs between 40°E and 150°E, corresponding to the Cthulhu region.