What each input means (and typical ranges)

Meteorology

• Wind @10 m (m/s) — Mean wind speed measured at 10 m. Typical near-surface winds range ~0–15 m/s; strong events >15 m/s are possible in storms. Used to compute friction velocity and erosion initiation.
• Stability class (A–F) — Pasquill–Gifford/Turner stability: A,B = very/ moderately unstable (sunny, convective); C = slightly unstable; D = neutral (overcast, windy); E,F = stable (night, light winds). Controls σ_y, σ_z growth and reflection term. (Turner, 1969)
• Wind dir from N (°) — Meteorological direction the wind blows from (0–360). Used with field orientation to compute effective fetch.
• Include ground reflection — Image-source term that doubles the vertical Gaussian about z=0 for a ground-level receptor (standard in simple Gaussian plumes). (Turner, 1969)

Soil & texture

• Sand / Silt / Clay (%) — Particle size fractions; auto-normalized to sum 100%. USDA texture triangle is the reference classification. (USDA NRCS, 2017)
• Organic carbon, FOC (%) — Soil organic carbon fraction. Commonly ~0.5–5% in mineral topsoils but broader 0.1–10% occurs depending on land use and climate; drives sorption via K_oc. (USDA NRCS, 2017)
• Topsoil water, ST (%) — Gravimetric water content. Typical agricultural topsoils range roughly 5–30% by mass; dries down under warm/windy conditions.
• Time step, TS (s) — Integration step for wind erosion flux Y_W. Shorter steps resolve transients; 600–3600 s is a practical range.

Roughness & Vegetation / Management

• Random roughness RRUF (mm) — Standard deviation of microrelief heights after removing slope/tillage trend; typical freshly tilled fields ~10–30 mm, smoother crusted surfaces ~2–10 mm. Larger values increase sheltering and reduce erosion. (Potter et al., 1990; Vinci et al., 2020)
• Wind vs ridge angle (°) — Angle between wind and oriented roughness (ridges). Max shelter near 90° (cross-ridge).
• Ridge height RHTT (mm) — Oriented roughness height; higher ridges generally reduce erosion flux via sheltering.
• Conventional / Conservation / No-till fractions — Fractions (0–1) of the field under each tillage system; the model converts to an effective management multiplier.
• Residue-treated fraction — Fraction with residue retained (0–1); residue strongly reduces erodibility and C-factor.
• Cover crops fraction — Fraction with live cover in the erosive season (0–1); reduces C-factor.
• Crop C-factor (Panagos 2015) — RUSLE cover-management factor (unitless). Typical values: perennial/forest ≪ 0.1; small grains/forage ~0.05–0.3; row crops higher depending on residue and cover. You can use Panagos et al. (2015) EU-scale estimates as guidance. (Panagos et al., 2015; ESDAC)

Geometry, Sorption & Receptor

• Field length FL (km), Field width FW (km) — Planform dimensions; combined with wind/row angle to compute effective fetch width WL. Typical fields: 0.1–1 km scale.
• K_oc (mL/g) — Organic carbon–water partition coefficient driving pesticide sorption (K_d=K_oc·f_oc). Non-ionic pesticides span orders of magnitude (~10–10⁵ mL/g). (ECETOC, 2013; Baker & Hites, 2000)
• Pesticide mass per m², m (mg) — Mass of active ingredient present in the wind-erodible surface layer per ground area (mg/m²). Derive from application rate × interception × degradation/volatilization losses.
• Soil particle diameter DIAM (m) — Characteristic eroding particle/aggregate diameter. Wind-erodible fractions often tens to a few hundred micrometres (e.g., 20–200 µm); emitted PM includes finer particles.
• Source height Hs (m) — Effective release height (0–2 m typical for surface erosion; higher if lofted).
• Receptor distance X (m) — Downwind distance to sampler; tens to thousands of meters are common in near-field assessments.
• Sampler height Z (m) — Inlet height; 1–2 m typical for near-ground samplers.

Temporal plume (PG moving frame)

• PG stability class — Same A–F notion but using Pasquill–Gifford rural σ fits for time-varying plan view. (Briggs, 1973; Turner, 1969)
• Wind speed U (m/s) — Advection speed for moving-frame plume (x_rel = x − U·t).
• Downwind extent (km), Crosswind half-width (km) — Domain size for the plan view.
• Grid resolution (m) — Raster cell size; 25–100 m is a good balance.
• Log color scale — Toggle to reveal gradients over several orders of magnitude.
• Δt (s), Time window (min), Play — Controls for stepping and animating the moving plume.
• Focus distance X (m) — Used to extract a time-series at a fixed downwind location.

Notes on typical ranges and interpretation

• Ranges above are indicative; local soils, crops, and weather can differ substantially.
• C-factor and management fractions interact multiplicatively; small improvements (residue/cover) can yield order-of-magnitude reductions in Y_W.
• Stability strongly affects downwind decay; stable nights (E–F) keep plumes narrow and elevated; unstable days (A–C) dilute faster.

References

1. Turner, D. B. (1969). Workbook of Atmospheric Dispersion Estimates, U.S. EPA.
2. Briggs, G. A. (1973). Diffusion Estimation for Small Emissions; Pasquill–Gifford σ_y, σ_z equations.
3. USDA NRCS (2017). Soil Survey Manual, Ch. 3 — USDA texture triangle.
4. Potter, K. N., Zobeck, T. M., & Hagan, L. J. (1990s). Microrelief/Random roughness and wind erosion indices.
5. Vinci, A. et al. (2020). Comparative evaluation of random roughness indices.
6. Panagos, P. et al. (2015). Estimating the soil erosion cover-management (C) factor at the European scale.
7. ESDAC (JRC). C-factor datasets and documentation for Europe.
8. ECETOC (2013). Organic carbon–water partition (K_oc) overview; ranges across chemicals. - Technical report 123
9. Baker, J., & Hites, R. (2000). Estimating K_oc for persistent organic pollutants.