# ISCST3 Tech Guide

## 5. Symbols

Symbol |
Definition |

A | Linear decay term for vertical dispersion in Schulman-Scire downwash (dimensionless) |

Ae | Effective area for open pit emissions (dimensionless) |

D | Exponential decay term for Gaussian plume equation (dimensionless) |

DB | Brownian diffusivity (cm/s) |

Dr | Relative pit depth (dimensionless) |

de | Effective pit depth (m) |

dp | Particle diameter for particulate emissions (µm) |

ds | Stack inside diameter (m) |

Fb | Buoyancy flux parameter (m4/s3) |

Fd | Dry deposition flux (g/m2) |

Fm | Momentum flux parameter (m4/s2) |

FQ | Plume depletion factor for dry deposition (dimensionless) |

FT | Terrain adjustment factor (dimensionless) |

Fw | Wet deposition flux (g/m2) |

f | Frequency of occurrence of a wind speed and stability category combination (dimensionless) |

g | Acceleration due to gravity (9.80616 m/s2) |

hb | Building height (m) |

he | Plume (or effective stack) height (m) |

hs | Physical stack height (m) |

hter | Height of terrain above stack base (m) |

hs´ | Release height modified for stack-tip downwash (m) |

hw | Crosswind projected width of building adjacent to a stack (m) |

>k | von Karman constant (= 0.4) |

L | Monin-Obukhov length (m) |

Ly | Initial plume length for Schulman-Scire downwash sources with enhanced lateral plume spread (m) |

Lb | Lesser of the building height and crosswind projected building width (m) |

Alongwind length of open pit source (m) | |

P(x,y) | Profile adjustment factor (dimensionless) |

p | Wind speed power law profile exponent (dimensionless) |

QA | Area Source pollutant emission rate (g/s) |

Qe | Effective emission rate for effective area source for an open pit source (g/s) |

Qi | Adjusted emission rate for particle size category for open pit emissions (g/s) |

Qs | Pollutant emission rate (g/s) |

Q | Total amount of pollutant emitted during time period (g) |

R | Precipitation rate (mm/hr) |

Ro | Initial plume radius for Schulman-Scire downwash sources (m) |

R(z,zd) | Atmospheric resistance to vertical transport (s/cm) |

r | Radial distance range in a polar receptor network (m) |

ra | Atmospheric resistance (s/cm) |

rd | Deposition layer resistance (s/cm) |

s | Stability parameter = FUNC {g {{ theta}/ z } over {T_a}} |

S | Smoothing term for smoothing across adjacent sectors in the Long Term model (dimensionless) |

SCF | Splip correction factor (dimensionless) |

Sc | Schmidt number = FUNC { upsilon /D_B } (dimensionless) |

St | Stokes number = FUNC { (v_g/g)```(u_*^2/upsilon) } (dimensionless) |

Ta | Ambient temperature (K) |

Ts | Stack gas exit temperature (K) |

uref | Wind speed measured at reference anemometer height (m/s) |

us | Wind speed adjusted to release height (m/s) |

u* | Surface friction velocity (m/s) |

V | Vertical term of the Gaussian plume equation (dimensionless) |

Vd | Vertical term with dry deposition of the Gaussian plume equation (dimensionless) |

vd | Particle deposition velocity (cm/s) |

vg | Gravitational settling velocity for particles (cm/s) |

vs | Stack gas exit velocity (m/s) |

X | X-coordinate in a Cartesian grid receptor network (m) |

xo | Length of side of square area source (m) |

Y | Y-coordinate in a Cartesian grid receptor network (m) |

Direction in a polar receptor network (degrees) | |

x | Downwind distance from source to receptor (m) |

xy | Lateral virtual point source distance (m) |

xz | Vertical virtual point source distance (m) |

xf | Downwind distance to final plume rise (m) |

x* | Downwind distance at which turbulence dominates entrainment (m) |

y | Crosswind distance from source to receptor (m) |

z | Receptor/terrain height above mean sea level (m) |

zd | Dry deposition reference height (m) |

zr | Receptor height above ground level (i.e. flagpole) (m) |

zref | Reference height for wind speed power law (m) |

zs | Stack base elevation above mean sea level (m) |

zi | Mixing height (m) |

zo | Surface roughness height (m) |

Entrainment coefficient used in buoyant rise for Schulman-Scire downwash sources = 0.6 | |

Jet entrainment coefficient used in gradual momentum plume rise calculations FUNC {~=~{1 over 3} + {{u_s} over {v_s}}} | |

Plume rise (m) | |

Potential temperature gradient with height (K/m) | |

Escape fraction of particle size category for open pit emissions (dimensionless) | |

Precipitation scavenging ratio (s-1) | |

Precipitation rate coefficient (s-mm/hr)-1 | |

pi = 3.14159 | |

Decay coefficient = 0.693/T1/2 (s-1) | |

Stability adjustment factor (dimensionless) | |

Fraction of mass in a particular settling velocity category for particulates (dimensionless) | |

Particle density (g/cm3) | |

Density of air (g/cm3) | |

Horizontal (lateral) dispersion parameter (m) | |

Initial horizontal dispersion parameter for virtual point source (m) | |

Effective lateral dispersion parameter including effects of buoyancy-induced dispersion (m) | |

Vertical dispersion parameter (m) | |

Initial vertical dispersion parameter for virtual point source (m) | |

Effective vertical dispersion parameter including effects of buoyancy-induced dispersion (m) | |

Viscosity of air 0.15 cm2/s | |

Absolute viscosity of air 1.81 x 10-4 g/cm/s | |

Concentration (µg/m3) | |

Concentration with dry deposition effects) |