Deposition-Velocity

ModelingToolkit implementation of particle (aerosol) dry deposition from Seinfeld & Pandis (2006), Atmospheric Chemistry and Physics, 2nd ed., Chapter 19 (Dry Deposition), Eq. 19.7. Computes the particle dry deposition velocity v [m/s] for a single aerosol size and the corresponding first-order deposition rate k = v/z [1/s], as a resistance network: v = 1/(R_a + R_b + R_a*R_b*V_s) + V_s, where R_a is the aerodynamic resistance (Eqs. 19.13-19.14), R_b is the quasi-laminar sublayer resistance (Eq. 19.27), and V_s is the gravitational settling velocity (Eq. 9.42). R_b combines Brownian diffusion (Schmidt number), inertial impaction (Stokes number) and interception, with land-use-dependent collector geometry from the Seinfeld & Pandis Table 19.2 characteristic-radius table. Migrated from AtmosphericDeposition.jl@e4468c79 src/dry_deposition.jl:1040 (the DryDepositionAerosol builder); its DryDepParticle kernel (src/dry_deposition.jl:272) and the whole helper chain (ra, mu, mfp, cc, vs, dParticle, sc, stSmooth/stVeg, RbParticle) are inlined. Purely algebraic: no differential states -- the 27 computed quantities are observed variables defined by inline expressions.

ModelingToolkit implementation of the complete gas dry-deposition velocity model from Seinfeld & Pandis (2006), Atmospheric Chemistry and Physics, 2nd ed., Chapter 19 (Dry Deposition), Eq. 19.2 (deposition velocity) and Eq. 19.1 (deposition flux). The gas dry-deposition velocity follows the resistance-in-series model: a depositing gas crosses three resistances stacked in series between the reference height and the surface -- the aerodynamic resistance r_a (turbulent transport through the surface layer, Eq. 19.14), the quasi-laminar resistance r_b (molecular diffusion across the thin stagnant sublayer in contact with the surface, Eq. 19.17), and the surface resistance r_c (uptake by the canopy along four parallel pathways, Wesely 1989, Eq. 19.50). The deposition velocity is the reciprocal of their sum, v_d = 1/(r_a + r_b + r_c), and the downward deposition flux is F = -v_d*C for a gas concentration C at the reference height. Migrated from AtmosphericDeposition.jl@e4468c79 src/seinfeld_pandis_ch19.jl:416 (`DryDepositionGas` @component), which composes three MTK subsystems via `System(eqs, t; systems=[aero, qlam, surf])` plus its own coupling equations. Represented here as a subsystem-composed ESS model (spec section 4.7): the `aero` subsystem inlines the already-migrated AerodynamicResistance component (aerodynamic_resistance.esm, esm-x8pg), `qlam` inlines QuasiLaminarResistanceGas (quasi_laminar_gas.esm, esm-t3wp), and `surf` inlines SurfaceResistance (surface_resistance.esm, esm-ug1i), wired together by seven top-level coupling equations. Algebraic (no time derivative): u_star, C, G and T_s are input parameters; r_t, v_d and F are algebraic state outputs.

Composite particle dry-deposition model from Seinfeld & Pandis (2006), Atmospheric Chemistry and Physics, 2nd ed., Chapter 19 (Dry Deposition). Given the surface-layer friction velocity and an aerosol particle's properties it computes the particle dry deposition velocity v_d (Eq. 19.7) and the resulting downward deposition flux F (Eq. 19.1). Eq. 19.7, v_d = 1/(r_a + r_b + r_a*r_b*v_s) + v_s, combines the resistance-network pathway -- turbulent transport through the aerodynamic resistance r_a and the quasi-laminar boundary-layer resistance r_b, with the r_a*r_b*v_s cross term capturing gravitational settling acting inside the resistance network -- with a direct gravitational-settling term v_s; the flux F = -v_d*C (Eq. 19.1) is negative for downward transport. The competition between Brownian diffusion (efficient for sub-0.1 um particles) and inertial impaction (efficient for super-um particles) leaves a deposition-velocity minimum at accumulation-mode sizes. Migrated from AtmosphericDeposition.jl@e4468c79 src/seinfeld_pandis_ch19.jl:479 (the DryDepositionParticle @component), which composes three MTK subsystems via System(eqs, t; systems=[aero, settling, qlam]). Represented here as a subsystem-composed ESS model (spec §4.7): the aero subsystem inlines the already-migrated AerodynamicResistance component (aerodynamic_resistance.esm, esm-x8pg), settling inlines ParticleSettling (particle_settling.esm, esm-egwt) and qlam inlines QuasiLaminarResistanceParticle (quasi_laminar_particle.esm, esm-brbr), wired by six top-level coupling equations. Purely algebraic (no D() time-derivative anywhere): u_star and C are input parameters; v_d and F are algebraic state outputs.

Net wet deposition diagnostics — wet deposition flux, washout ratio, and wet deposition velocity — for a trace species removed from the atmosphere by falling rain, from Seinfeld & Pandis (2006), Atmospheric Chemistry and Physics, 2nd ed., Chapter 20 (Wet Deposition), Eqs. 20.6-20.9. Given the species concentration in ground-level rainwater (C_rain), its gas-phase concentration in air (C_air), and the precipitation rate (p₀), the component evaluates three quantities: the wet deposition flux F_w = C_rain·p₀ (Eq. 20.7) — the downward species mass flux carried to the surface by rain; the dimensionless washout ratio w_r = C_rain/C_air (Eq. 20.6) — a measure of how strongly the species partitions into rainwater; and the wet deposition velocity u_w = F_w/C_air (Eq. 20.8), equivalently w_r·p₀ (Eq. 20.9) — the flux normalized by the air-phase concentration. Migrated from AtmosphericDeposition.jl@e4468c79 src/seinfeld_pandis_2006_ch20.jl:451 (`WetDepositionFlux` @component). Flat observed-only algebraic model: C_rain, C_air and p₀ are the input parameters and F_w, w_r, u_w are the algebraic outputs, each fixed by one equation with no time derivative. The upstream @component is a single flat System with no subsystems; the migration-tracker `coupling.couple` feature tag and `depends_on: ParticleScavengingCoeff, GasScavengingCoeff` describe a conceptual relationship that the source code does not implement, so this is migrated as a standalone flat model.