Phase-averaged M³ measurement versus model comparison for E_c = 0.520 eV and E_w = 0.090 eV. M³-inferred surface abundances are compared with model abundances sampled at the corresponding phase, local-time, and latitude bins. Panels (a) and (b) show M³ and model surface abundance as a function of local time for the low-latitude 0°–30° and midlatitude 30°–60° bins, respectively. Model values are shown with cross symbols, and M³ values are shown with circles. Gray vertical bars in panels (a) and (b) show the range of model abundances sampled within the corresponding latitude and local-time bin. Panels (c) and (d) show signed residuals, defined as model minus M³ abundance. Points are colored by lunar phase angle, with magnetospheric sector labels shown next to the color bar.