(a) Spatial variations in magnetic Reynolds number (R_M (Eq. (22)), left) and (b) thermal ionization fraction (x_e, right) for WASP-18 b. Large areas of the dayside are in the intermediate and high-R_M regimes, while ionization varies over many orders of magnitude, motivating an anisotropic drag treatment that accounts for local conductivity and magnetic geometry. The lines show gas temperature-pressure profiles averaged over all latitudes and over different regions in the atmosphere: dayside (−90^◦< ϕ ≤ 90^◦), nightside (|ϕ| > 90^◦), morning (−97.5^◦≤ ϕ ≤ −82.5^◦) and evening terminator (82.5^◦≥ ϕ ≥ 97.5^◦). The results of the simulation with anisotropic drag were used in the calculation of R_M, x_e, and the averaged temperature-pressure profiles shown here.