Methane Reaction-Diffusion Filter in Permafrost (2D)

This 2D companion to the 3D permafrost methane simulator computes the same soil-column biofilter through a completely different, independently derived numerical method. Rather than following individual methane molecules as random-walking particles, it discretizes the real advection-diffusion-reaction partial differential equation onto a finite-difference grid spanning a soil cross-section, and integrates it forward in time with an explicit, mass-conserving scheme (Fickian diffusion via a 5-point Laplacian, a conservative upwind advection term for the buoyant upward drift, first-order oxidation kinetics above the water table, and patchy production hotspots below it, modeling the real spatial heterogeneity of organic-rich decomposition zones that a rotationally-symmetric 3D column cannot show). The live heatmap renders the CH₄ concentration field directly, a side profile plots the horizontally-averaged concentration against depth, and the same emission-flux, oxidation-rate and filter-efficiency readouts as the 3D sim let you compare the two models' predictions side by side.