Gaussian_dispersion

Lagrangian Gaussian puff horizontal dispersion model based on turbulent velocity fluctuation standard deviations (σu). Integrates the growth of horizontal dispersion standard deviations sigma_x and sigma_y from the Kolmogorov-type closure d(sigma)/dt = sqrt(2)*sigma_u, and computes the ground-level centerline concentration per unit mass assuming a top-hat vertical distribution within the lowest grid layer (height dz). Migrated from EnvironmentalTransport.jl@a48559c4 src/GaussianDispersion.jl:378 (GaussianKC @component). When coupled, sigma_u_x and sigma_u_y are provided by BoundaryLayerMixingKC and z_agl is provided by Puff; in standalone mode all three are treated as constant parameters.

Classic Gaussian plume dispersion model parameterized with Pasquill-Gifford-Briggs (PGB) stability classification and dispersion coefficients. Given the current puff position (lon, lat) and height above ground (z_agl), classifies atmospheric stability from near-surface meteorology (wind speed, solar radiation, cloud fraction, temperature lapse), selects Briggs dispersion-curve coefficients, computes the haversine downwind distance from the source, and evaluates horizontal (sigma_h) and vertical (sigma_z) dispersion widths and the ground-level Gaussian concentration (C_gl). Migrated from EnvironmentalTransport.jl@a48559c4 src/GaussianDispersion.jl:83. When coupled with Puff, lon/lat/z_agl are supplied by the Puff component; in standalone mode they are treated as constant parameters.