AQS Air Dispersion Modeling 3

Question 1

The AERMAP terrain preprocessor in the AERMOD modeling system is used to:

Accepted Answer

Extract terrain elevation data and compute hill height scales for sources and receptors

Answer

AERMAP processes digital elevation model (DEM) data to assign terrain heights to receptors and sources and compute the hill height scales required by AERMOD's terrain algorithms.

Question 2

Under stable atmospheric conditions (Pasquill-Gifford Class E or F), which plume behavior pattern is most commonly observed?

Accepted Answer

Fanning — wide horizontal spread with minimal vertical mixing

Answer

Fanning plumes occur under stable conditions because strong temperature stratification suppresses vertical turbulence, causing the plume to spread primarily in the horizontal crosswind direction.

Question 3

For regulatory modeling to compare with the 24-hour PM2.5 National Ambient Air Quality Standard, the model output should be analyzed using which averaging period?

Accepted Answer

24-hour average concentrations

Answer

The 24-hour PM2.5 NAAQS (35 µg/m³) requires model predictions to be expressed as 24-hour averages to allow direct comparison with the standard.

Question 4

A wind rose diagram is primarily used to display:

Accepted Answer

The frequency distribution and speed of winds from different compass directions at a monitoring site

Answer

A wind rose shows the frequency of occurrence and wind speed magnitudes from each compass direction at a location over a specified period, characterizing the local wind climate.

Question 5

The 'critical wind speed' for maximum ground-level concentration from a buoyant stack plume is the wind speed at which:

Accepted Answer

The reduction in plume rise from stronger winds exactly offsets the increased horizontal dilution, yielding the highest ground concentration

Answer

At the critical wind speed, greater winds simultaneously reduce buoyancy-induced plume rise and increase dilution; the balance point between these competing effects produces the maximum ground-level concentration.

(AQS) Air Quality Specialist Certification Practice Test

(AQS) Air Quality Specialist Certification Practice Test

AQS Air Dispersion Modeling 3