Atmospheric dispersion modeling

Atmospheric dispersion modeling uses mathematical simulations to estimate how pollutants or other airborne substances move, dilute, transform, and deposit in the atmosphere.

Gaussian plume model: A steady-state model that represents a pollutant plume with Gaussian concentration profiles across and above the wind direction. It is the classic formulation for estimating concentrations from continuous emissions in steady winds.
Air quality modeling: The simulation of atmospheric pollutant emissions, transport, chemistry, and concentrations. Dispersion modeling supplies the transport component of broader air-quality simulations.
Emission inventory: A systematic estimate of pollutant emissions from sources across a region and time period. Inventories provide the source strengths that regional dispersion calculations require.
Eulerian model: A model that calculates atmospheric quantities at fixed locations on a spatial grid. Eulerian models solve for concentrations on grids, unlike particle-tracking approaches.
Lagrangian dispersion model: A model that tracks air parcels or particles as they move through a simulated flow. Tracking particles captures changing winds and turbulent transport without assuming a fixed plume shape.
Regulatory air dispersion modeling: The use of approved dispersion models to estimate pollutant concentrations for permitting and compliance decisions. Regulators use specified model settings to test whether proposed sources meet air-quality limits.
Meteorological data: Measurements or analyses describing atmospheric conditions such as wind, temperature, and pressure. Winds and temperature structure determine where and how quickly pollutants disperse.
Box model: A simplified model that treats a region as a well-mixed volume with defined inputs and outputs. It sacrifices spatial plume detail for a compact description of regional pollutant budgets.
Computational fluid dynamics: Numerical methods for solving fluid-flow equations across spatially resolved domains. CFD resolves buildings and terrain that simpler dispersion models represent only approximately.
Emergency response modeling: The rapid use of models to estimate hazards and guide decisions during accidents or releases. A release simulation can help identify downwind areas that may need protective action.

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Air pollution controlRelated: Models estimate how controlled emissions affect concentrations downwind.