Soil porosity (﹩\phi ﹩), and thus the fraction of the surface exposed to the underlying pore space, changes the rate of methane evaporation. Low-porosity, more densely packed regolith restricts (a) surface methane flux compared with loosely packed, high-porosity materials, which directly influences (b–d) the surface energy balance and (e) the scale of the PBL. The maximum depth on the PBL on Tsol 3 is listed in the main text. Note that panel (a) is scaled by ﹩1\times {10}^{-6}﹩. Individual simulations are labeled in panel (a) and include simulations with prescribed porosities (﹩\phi ﹩ = 0.5,0.1,0.05, and 0.02).