rate_RO2NO_b2
GEOS-Chem gas-phase reaction rate laws — the 37 rate-coefficient builder functions of GasChem.jl src/geoschem_ratelaws.jl, adapted from the GEOS-Chem KPP/fullchem mechanism (github.com/geoschem/geos-chem, commit 4722f288). Each builder computes a single reaction rate coefficient k from temperature and air number density: constant rates (constant_k, constant_k_1), modified-Arrhenius forms in ppb and SI molecular units (arrhenius_ppb, arrhenius_ppb_3, arrhenius_mlc_SI, arrhenius_mlc_1, arrplus_*, tunplus_*), Troe / third-body pressure-dependent falloff rates (arr_3rdbody, arr_3rdbody_1, rate_OHCO, rate_PAN_abab, rate_PAN_acac, eq_const, eq_const_1), and a family of mechanism-specific rates for HO2, RO2+NO, isoprene, glycolaldehyde, DMS and HNO3 chemistry. Each rate law is migrated as an independent purely-algebraic model: the inputs (T, num_density, Arrhenius coefficients) are parameters, the rate coefficient k is the single state variable defined by one algebraic equation, and an inline test reproduces the rate constant asserted by the corresponding @testitem in GasChem.jl test/geoschem_ratelaws_test.jl (compiled at T=293 K, num_density = 2.7e19 molec/cm^3). The GEOS-Chem license applies (github.com/geoschem/geos-chem/blob/main/LICENSE.txt).
Description
GEOS-Chem gas-phase reaction rate laws — the 37 rate-coefficient builder functions of GasChem.jl src/geoschem_ratelaws.jl, adapted from the GEOS-Chem KPP/fullchem mechanism (github.com/geoschem/geos-chem, commit 4722f288). Each builder computes a single reaction rate coefficient k from temperature and air number density: constant rates (constant_k, constant_k_1), modified-Arrhenius forms in ppb and SI molecular units (arrhenius_ppb, arrhenius_ppb_3, arrhenius_mlc_SI, arrhenius_mlc_1, arrplus_, tunplus_), Troe / third-body pressure-dependent falloff rates (arr_3rdbody, arr_3rdbody_1, rate_OHCO, rate_PAN_abab, rate_PAN_acac, eq_const, eq_const_1), and a family of mechanism-specific rates for HO2, RO2+NO, isoprene, glycolaldehyde, DMS and HNO3 chemistry. Each rate law is migrated as an independent purely-algebraic model: the inputs (T, num_density, Arrhenius coefficients) are parameters, the rate coefficient k is the single state variable defined by one algebraic equation, and an inline test reproduces the rate constant asserted by the corresponding @testitem in GasChem.jl test/geoschem_ratelaws_test.jl (compiled at T=293 K, num_density = 2.7e19 molec/cm^3). The GEOS-Chem license applies (github.com/geoschem/geos-chem/blob/main/LICENSE.txt).
Reference
_source_ref: GasChem.jl@8c12c048482b515fb8eb2110bf8ab4b4f4e71309:src/geoschem_ratelaws.jl:461 (rate_RO2NO_b2 rate-law builder function).
Rate law for the ‘B’ (NO2-forming) branch of RO2 + NO reactions with a1 > 1 (ETO2/A3O2/R4O2/B3O2 + NO): k = k0*(1 - fyrno3) * C, the complement of the rate_RO2NO_a2 branching ratio.
Migration shape: the upstream rate_RO2NO_b2 returns a Catalyst ReactionSystem carrying zero reactions and one variable k(t) bound by a single algebraic equation k ~ model: the rate-law inputs (T, num_density, Arrhenius coefficients) are type: parameter, the output k is the single type: state variable, and equations holds the one defining equation. No equation carries a D(.) operator, so the trajectory is constant in time and the inline test samples at t=0 (the observed-only convention of sibling files multiple_removal.esm / ope.esm).
Units: variables carry no units field — the rate expression folds the upstream MTK unit conversions into numeric literals, so every quantity is nominally dimensionless to the structural validator. This is the convention of the sibling GEOS-Chem file geoschem_fullchem.esm; physical units are documented in prose in each variable’s description.
Tolerance rationale (model-level rel=1e-8 / abs=1e-30): the rate law is a single closed-form algebraic expression evaluated once (no time integration, no stiff dynamics). rel=1e-8 sits at the upstream Julia approximate-equality default (approx uses rtol=sqrt(eps(Float64))=~1.49e-8) and comfortably absorbs the libm exp / ^ / log10 rounding differences between the Julia reference values and the Python ESS runner; abs=1e-30 is a near-zero floor that gates no assertion here (the smallest pinned rate constant across the file is eq_const k=~2.1e-27).
Upstream test reproduction: the inline test upstream_rate_RO2NO_b2 pins k at the parameter defaults to the value asserted by the @testitem "rate_RO2NO_b2" block in GasChem.jl test/geoschem_ratelaws_test.jl, which compiles the rate law at T=293.0 K and num_density=2.7e19/N_A*cm3_m3 mol/m^3 and checks the resulting rate constant k._
Parameters
| Name | Units | Default | Description |
|---|---|---|---|
T | 293.0 | Air temperature (K). Default 293.0 K is the scenario temperature of the upstream geoschem_ratelaws_test.jl RateLawSetup test snippet. | |
num_density | 44.834554813693856 | Number density of air (mol/m^3). Default 44.834554813693856 mol/m^3 equals 2.7e19 molec/cm^3 — the upstream test value 2.7e19/N_A*cm3_m3 (N_A = 6.02214076e23, cm3_m3 = 1.0e6). | |
a0 | 2.6e-12 | Arrhenius pre-exponential of the base rate k0. | |
c0 | 365.0 | Arrhenius exponential temperature term of k0. [K] | |
a1 | 2.0 | Carbon-number parameter of the branching ratio. |
Observed
| Name | Units | Default | Description |
|---|---|---|---|
k | Reaction rate coefficient produced by the rate_RO2NO_b2 rate law, output in ppb^-1*s^-1. Defined by one algebraic equation; the system carries no time derivative. |
Observed expressions
$$ k = a0 \cdot e^{\frac{c0}{T}} \cdot \frac{300.0}{T}^{0.0} \cdot 1 \times 10^{-6} \cdot 1000000.0 \cdot \left(1.0 - \frac{\frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{1.0 + \frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{0.826 \cdot e^{\frac{0.0}{T}} \cdot \frac{300.0}{T}^{8.1} \cdot 1 \times 10^{-6} \cdot 1000000.0}} \cdot 0.411^{\frac{1.0}{1.0 + \log_{10}\left(\frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{0.826 \cdot e^{\frac{0.0}{T}} \cdot \frac{300.0}{T}^{8.1} \cdot 1 \times 10^{-6} \cdot 1000000.0}\right) \cdot \log_{10}\left(\frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{0.826 \cdot e^{\frac{0.0}{T}} \cdot \frac{300.0}{T}^{8.1} \cdot 1 \times 10^{-6} \cdot 1000000.0}\right)}}}{1.0 + \frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{1.0 + \frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{0.826 \cdot e^{\frac{0.0}{T}} \cdot \frac{300.0}{T}^{8.1} \cdot 1 \times 10^{-6} \cdot 1000000.0}} \cdot 0.411^{\frac{1.0}{1.0 + \log_{10}\left(\frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{0.826 \cdot e^{\frac{0.0}{T}} \cdot \frac{300.0}{T}^{8.1} \cdot 1 \times 10^{-6} \cdot 1000000.0}\right) \cdot \log_{10}\left(\frac{1.94 \times 10^{-22} \cdot e^{0.97 \cdot a1} \cdot num_{density} \cdot 6.02214076 \times 10^{17}}{0.826 \cdot e^{\frac{0.0}{T}} \cdot \frac{300.0}{T}^{8.1} \cdot 1 \times 10^{-6} \cdot 1000000.0}\right)}}}\right) \cdot num_{density} \cdot 1 \times 10^{-9} \cdot 6.02214076 \times 10^{17} $$Reaction rate coefficient produced by the rate_RO2NO_b2 rate law, output in ppb^-1*s^-1. Defined by one algebraic equation; the system carries no time derivative.
Raw .esm
Raw .esm JSON (this component)
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"notes": "source_ref: GasChem.jl@8c12c048482b515fb8eb2110bf8ab4b4f4e71309:src/geoschem_ratelaws.jl:461 (`rate_RO2NO_b2` rate-law builder function).\n\nRate law for the 'B' (NO2-forming) branch of RO2 + NO reactions with a1 > 1 (ETO2/A3O2/R4O2/B3O2 + NO): k = k0*(1 - fyrno3) * C, the complement of the rate_RO2NO_a2 branching ratio.\n\nMigration shape: the upstream `rate_RO2NO_b2` returns a Catalyst `ReactionSystem` carrying zero reactions and one variable k(t) bound by a single algebraic equation k ~ <rate expression> (the @constants in the source are MTK unit-bookkeeping; their numeric values N_A=6.02214076e23, cm3_m3=1.0e6, ppb_unit=1.0e-9, k_unit_inv=1.0e6 are folded into the .esm expression AST as literals). It is migrated here as a purely-algebraic `model`: the rate-law inputs (T, num_density, Arrhenius coefficients) are `type: parameter`, the output k is the single `type: state` variable, and `equations` holds the one defining equation. No equation carries a D(.) operator, so the trajectory is constant in time and the inline test samples at t=0 (the observed-only convention of sibling files multiple_removal.esm / ope.esm).\n\nUnits: variables carry no `units` field — the rate expression folds the upstream MTK unit conversions into numeric literals, so every quantity is nominally dimensionless to the structural validator. This is the convention of the sibling GEOS-Chem file geoschem_fullchem.esm; physical units are documented in prose in each variable's `description`.\n\nTolerance rationale (model-level rel=1e-8 / abs=1e-30): the rate law is a single closed-form algebraic expression evaluated once (no time integration, no stiff dynamics). rel=1e-8 sits at the upstream Julia approximate-equality default (`approx` uses rtol=sqrt(eps(Float64))=~1.49e-8) and comfortably absorbs the libm exp / ^ / log10 rounding differences between the Julia reference values and the Python ESS runner; abs=1e-30 is a near-zero floor that gates no assertion here (the smallest pinned rate constant across the file is eq_const k=~2.1e-27).\n\nUpstream test reproduction: the inline test `upstream_rate_RO2NO_b2` pins k at the parameter defaults to the value asserted by the `@testitem \"rate_RO2NO_b2\"` block in GasChem.jl test/geoschem_ratelaws_test.jl, which compiles the rate law at T=293.0 K and num_density=2.7e19/N_A*cm3_m3 mol/m^3 and checks the resulting rate constant k."
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]
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