What do the dispersion parameters σ_y and σ_z characterize in Gaussian plume modeling?

What do the dispersion parameters σ_y and σ_z characterize in Gaussian plume modeling?

• A. Temperature distribution
• B. Wind shear
• C. Horizontal and vertical spread due to turbulence
• D. Plume rise

Answer: (C)

In Gaussian plume modeling, the dispersion parameters describe how the plume spreads horizontally and vertically due to atmospheric turbulence. The horizontal dispersion parameter, σ_y, and the vertical dispersion parameter, σ_z, represent the standard deviations of the concentration profile across the crosswind and in height, respectively. They quantify how the plume widens as it is advected downwind, with larger values indicating more dilution and a broader plume. These parameters are central because the concentration field is modeled as a Gaussian in y and z, with σ_y and σ_z setting the plume’s cross-sectional widths. They depend on downwind distance, atmospheric stability, and surface roughness, and they generally grow with distance from the source, shaping how peak concentrations evolve downwind. They are not about temperature distribution, wind shear, or plume rise.

In Gaussian plume modeling, the dispersion parameters describe how the plume spreads horizontally and vertically due to atmospheric turbulence. The horizontal dispersion parameter, σ_y, and the vertical dispersion parameter, σ_z, represent the standard deviations of the concentration profile across the crosswind and in height, respectively. They quantify how the plume widens as it is advected downwind, with larger values indicating more dilution and a broader plume.

These parameters are central because the concentration field is modeled as a Gaussian in y and z, with σ_y and σ_z setting the plume’s cross-sectional widths. They depend on downwind distance, atmospheric stability, and surface roughness, and they generally grow with distance from the source, shaping how peak concentrations evolve downwind.

They are not about temperature distribution, wind shear, or plume rise.