Combined

Parameters-preset model representing typical remote/background tropospheric conditions with low NOx. Migrated from GasChem.jl@8c12c048 src/combined_system.jl:261 (`RemoteConditions` @component). Eleven species concentrations are declared as parameters in SI units (m⁻³); the model exposes them as algebraic outputs (`*_out`) so a parent system or test harness can read presets without depending on MTK parameter-introspection APIs. Based on Seinfeld & Pandis Chapter 6 background conditions: ~30 ppb O₃, ~10 ppt NO, ~20 ppt NO₂, ~80 ppb CO.

Combined tropospheric chemistry diagnostic system (Seinfeld & Pandis 2006, Chapter 6) — couples three photochemical subsystems into a comprehensive steady-state diagnostic model of tropospheric photochemistry: OH production from O3 photolysis (§6.1), the NOx photochemical cycle (§6.2), and CO oxidation chemistry (§6.3). Migrated from GasChem.jl@8c12c048 src/combined_system.jl:54 (`TroposphericChemistrySystem` @component). The three subsystems — `oh` (OHProduction), `nox` (NOxPhotochemistry), `co` (COOxidation) — are inlined verbatim (ESS spec §4.7 subsystem composition) from their already-migrated standalone .esm files; the parent supplies 14 coupling equations feeding the shared species (O3, NO, NO2, OH, HO2, CO, CH3O2, H2O, M, O2) into the subsystems and 9 combined-diagnostic equations (total/net O3 production, ozone production efficiency, NOx loss rate, HOx chain length). Purely algebraic — a steady-state diagnostic system with no time derivatives. SI units throughout (m^-3 for concentrations, m^3/s for bimolecular rate constants).

Parameters-preset component that exposes typical lower-troposphere chemical composition (Seinfeld & Pandis 2006, Chapter 6) as observable outputs. Migrated from GasChem.jl@280ee50f src/combined_system.jl:177 (`TypicalConditions` @component). The component declares 11 species concentrations as parameters with fixed default values in SI units (m^-3) for typical mid-latitude lower-tropospheric daytime conditions — total air number density M = 2.5e25 m^-3 at STP, O2 = 5.25e24 m^-3 (21% of M), H2O = 4.0e23 m^-3 (~50% RH at 298 K), O3 = 1.0e18 m^-3 (~40 ppb), NO = 2.5e15 m^-3 (~0.1 ppb), NO2 = 2.5e16 m^-3 (~1 ppb), CO = 2.5e18 m^-3 (~100 ppb), CH4 = 4.5e19 m^-3 (~1800 ppb), OH = 1.0e12 m^-3 (typical daytime), HO2 = 1.0e14 m^-3 (typical daytime), CH3O2 = 1.0e14 m^-3 (typical daytime) — and 11 passthrough algebraic equations of the form `<species>_out ~ <species>` that publish each species parameter on the canonical `<species>_out(t)` observable name. This design exists because the upstream `TroposphericChemistrySystem` consumes species concentrations on the bare names (M, O2, H2O, O3, NO, NO2, OH, HO2, CO, CH4, CH3O2) and a downstream consumer can compose a conditions preset by binding its preset parameters into those input variables — the `_out` suffix makes the conditions component a publishable upstream of any compose graph. Parameterized as observed-only with 11 passthrough/identity equations — no time derivatives, no `@register_symbolic` dependencies, no PDE — matching the upstream `length(equations(sys)) == 11` / `length(unknowns(sys)) == 11` structural shape.

Parameter-preset condition system representing typical urban-air-quality lower-troposphere conditions with elevated NOx, CO, and reduced HOx, following Seinfeld & Pandis (2006) Chapter 6. Migrated from GasChem.jl@8c12c048 src/combined_system.jl:219 (`UrbanConditions` @component). The component declares 11 species number-density parameters (M, O2, H2O, O3, NO, NO2, CO, CH4, OH, HO2, CH3O2) with urban-regime defaults in SI units (m^-3) and 11 corresponding `_out` output state variables, one per parameter, defined by identity equations `*_out ~ *`. The component is a sibling preset to `TypicalConditions` (background-air defaults) and `RemoteConditions` (clean-remote defaults); together they parametrize the three canonical regimes the upstream `TroposphericChemistrySystem` is exercised against. Compared to TypicalConditions: NO is 100x higher (10 vs 0.1 ppb), NO2 is 30x higher (30 vs 1 ppb), CO is 20x higher (2000 vs 100 ppb), and OH/HO2 are reduced 2x (titrated by the elevated NOx and CO oxidation chain). All concentrations are positive number densities at standard temperature and pressure; the `_out` indirection lets downstream consumers wire the preset values into the canonical tropospheric-chemistry input interface without renaming.