Gaussian Plume Concentration Calculator

Example preset

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Inputs

Emission rate Q

Wind speed u (m/s)

Please enter u as the representative wind speed near the discharge height (be careful when using the wind speed 10m above the ground as is).

Effective discharge height H (m)

H = chimney physical height + plume rise (this tool does not calculate rise separately).

Stability class (A~F)

Downwind distance x (m)

Lateral distance y (m)

Receptor height z (m)

Display unit

Ground reflection (image method)

Advanced options (line heatmap)

Line x min (m) Line x max (m) Number of line points N

heat map

Heat x min (m) Heat x max (m) Heat y half width (m) Heatmap x divisions Heatmap y divisions

Calculation result

Concentration C (selected unit)

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status

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σy (m)	—
σz (m)	—
model	—

Details (exponential term/intermediate value)

Centerline concentration profile (y=0, z=0)

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distance x	Concentration C (µg/m³)	log10(C+ε)

Isoconcentration heatmap (x-y, z=0)

low — high

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Formulas and assumptions

Reflection ON:C = Q/(2πuσyσz) × exp(-y²/(2σy²)) × [exp(-(z-H)²/(2σz²)) + exp(-(z+H)²/(2σz²))]
Reflection OFF: Calculate with the second term in square brackets as 0.
σy and σz use the Briggs rural approximation (A-F). Recommended x range: 100 to 10,000 m.
Results are short-term average estimates from a steady-state model. Apply time-averaging corrections when needed.
Set u to a representative wind speed near the emission height. Use caution when comparing with near-ground observations.

FAQ

What assumptions does the Gaussian plume model make?

It assumes steady wind, continuous emission from a point source, flat terrain, and statistical plume spreading. Use the result as a screening or learning estimate, not as a site-specific dispersion study.

What do stability classes A-F mean?

Stability classes describe atmospheric turbulence. A is very unstable with strong mixing, D is neutral, and F is stable with weaker vertical mixing.

What is ground reflection?

Ground reflection adds an image plume below the surface so the model approximates reflection from the ground. Turn it off only when your classroom case explicitly asks for no reflection.

Can I use this for regulatory compliance?

No. Compliance work needs approved methods, local meteorology, terrain, averaging times, receptor grids, and professional review.

Are my inputs uploaded somewhere?

No. Core calculations run in your browser. A share URL may encode parameters if you choose to copy and send it.