Tropospheric-Budget

Complete tropospheric mass-budget model for a trace species, from Seinfeld & Pandis (2006) Ch. 2 §2.3, Eqs. 2.13-2.17. A single linear first-order ODE on the species burden Q drives the dynamics: dQ/dt = (P_n + P_a + P_c) - (k_d + k_w + k_c + k_t)·Q — total production from natural emissions, anthropogenic emissions, and in-troposphere chemical production, balanced against first-order removal by dry deposition, wet deposition, chemical loss, and cross-tropopause transport to the stratosphere. The model also reports the algebraic diagnostics that the textbook builds on this budget: the total production rate P_total and removal rate R_total, the total first-order removal rate constant k_total, the per-pathway lifetimes tau_dry/tau_wet/tau_chem/tau_transport = 1/k_X, the total atmospheric lifetime tau_total = 1/k_total (Eq. 2.15), and the production-based lifetime tau_production = Q/P_total (Eqs. 2.16-2.17), which equals tau_total once the burden has relaxed to steady state. Migrated from GasChem.jl@280ee50f src/AtmosphericLifetime.jl:336 (`TroposphericBudget` @component). The system is linear with constant coefficients, so the burden has the exact closed form Q(t) = Q_ss + (Q_0 - Q_ss)·exp(-k_total·t) with steady state Q_ss = P_total/k_total; every inline-test expected value below is that analytic solution.