Radical-Chemistry

Stratospheric HOx catalytic ozone destruction cycle (Seinfeld & Pandis 2006 Ch. 5, §5.4, Eqs. 5.23-5.28). Two-state ODE on the radicals OH and HO2 driven by reactions with O3, atomic O, and NO; HOx = OH + HO2 is exactly conserved by construction (D(OH) + D(HO2) ≡ 0). Migrated from GasChem.jl@8c12c048 src/StratosphericChemistry.jl:187 (`HOxCycle` @component). All rate coefficients are temperature-dependent Arrhenius forms k_X = k_X_A · exp(C_X / T) with the Seinfeld & Pandis bimolecular CGS pre-factors converted to SI via the cm³/molec/s × 1e-6 → m³/s factor; SI rates and SI number-density concentrations (m^-3) are preserved verbatim from upstream.