Ozone

Stratospheric Chapman mechanism for ozone production and destruction (Seinfeld & Pandis 2006 Ch. 5, §5.2, Eqs. 5.1-5.17). Two-state ODE on atomic oxygen O and ozone O3 driven by the four canonical Chapman reactions: O2 photolysis (j_O2), three-body recombination O + O2 + M → O3 + M (k2 with power-law T-dependence (T_ref/T)^2.4), O3 photolysis (j_O3), and the O + O3 → 2 O2 odd-oxygen sink (k4 with Arrhenius temperature dependence). Odd oxygen Ox = O + O3 is *not* exactly conserved — the Chapman cycle has a net Ox source (2·j_O2·O2·M from O2 photolysis) balanced against an Ox sink (2·k4·O·O3 from the O+O3 reaction) — but on short timescales (≲ 10 s under default mid-stratosphere conditions) the net change is small (~4e-5 relative drift) and the upstream test treats it as quasi-conserved at rtol=1e-4. Migrated from GasChem.jl@8c12c048 src/StratosphericChemistry.jl:51 (`ChapmanMechanism` @component). Rate coefficients carry SI units throughout, converted from Seinfeld & Pandis CGS values via cm^6/molec^2/s × 1e-12 → m^6/s for the 3-body k2 and cm^3/molec/s × 1e-6 → m^3/s for the bimolecular k4.

POLLU air-pollution photochemistry mechanism from GasChem.jl. 20 species and 25 reactions (15 thermal + 10 photolytic) describing tropospheric NOx / odd-oxygen / hydrocarbon / sulfur chemistry. Introduced by Verwer (1994) as a stiff-ODE benchmark for chemical-kinetics integrators and widely used since as a standard stiff test problem. Hand-translated from the upstream Catalyst @reaction_network in GasChem.jl src/Pollu.jl: 25 rate constants carried verbatim as parameters, 20 species with their declared reservoir defaults, and 25 mass-action reactions numbered R1..R25 in the canonical POLLU order. All reaction rates are bare parameter references and all substrate stoichiometries are 1, so the serialized mass-action system matches the upstream combinatoric_ratelaws=false ReactionSystem exactly.

Comprehensive stratospheric ozone chemistry (Seinfeld & Pandis 2006, Chapter 5) — a monolithic 15-state ODE plus 5 algebraic family sums combining the Chapman mechanism, O(1D) photochemistry, the N2O NOx source, and the NOx / HOx / ClOx / BrOx catalytic ozone-destruction cycles. Migrated from GasChem.jl@8c12c048 src/StratosphericChemistry.jl:497. SI units throughout.

SuperFast gas-phase atmospheric chemistry mechanism from GasChem.jl. 12 active species + 3 quasi-constant reservoirs (O2/CH4/H2O; constant=true per ESS gt-ertm), 27 reactions covering tropospheric ozone chemistry. Regenerated from the upstream MTK ReactionSystem via mtk2esm (ESS gt-dod2). Fractional stoichiometries preserved directly (ESS gt-1e96); rate-law wrappers (arrhenius, third-body falloff, JPL 15-10 OH+CO, H2O-dependent HO2+HO2) inlined as Expression trees.