 Chapman ozone equilibrium

Chapman ozone equilibrium balances production and destruction of atomic oxygen and ozone in a minimal oxygen-only atmospheric photochemistry model. Write square brackets for number densities. Define photolysis rate coefficients $J_1,J_3$ and collisional rate constants $K_2,K_4$ byThe collision partner $\mathrm{M}$ removes excess formation energy without being consumed. The third-body requirement reflects conservation of energy and momentum conservation during ozone formation.^[ref]

Adding the reaction rate equations for atomic oxygen and ozone cancels their rapid interconversion. A local steady state givesIf ozone loss is predominantly photolytic, $J_3\gg K_4[\mathrm{O}]$, its separate balance isCombining the two balances yieldsThe two factors of two in oxygen-atom production and destruction cancel in the first balance. This is a sunlit local steady state, with specified temperature, radiation and background number densities; transport and additional catalytic chemistry need not obey this four-reaction estimate.