Air Dispersion Modeling

What is Air Dispersion Modeling?

Air dispersion modeling provides a visual mathematical simulation of how air pollutants disperse in the ambient atmosphere. Based on emissions source and meteorological data as well as topography information, a dispersion model calculates an estimate of the downwind concentration of pollutants as they travel away from emissions sources.

How are dispersion models used?

Dispersion models can be used to determine whether a new source will adversely impact an area or to predict whether the control of an individual source will have a beneficial effect. For example, these models are used to determine compliance with National Ambient Air Quality Standards (NAAQS) and other regulatory requirements, such as New Source Review (NSR) and Prevention of Significant Deterioration (PSD) regulations.

ADEQ Modeling Guidance for Permits 

ADEQ has developed a guidance document to help applicants understand air quality modeling procedures with regard to Air Quality Permit applications for sources located in Arizona under ADEQ jurisdiction | See Guidance >

ADEQ AERMET Pre-processed Meteorological Data 

ADEQ processed the meteorological data using AERMET version 16216 along with AERMINUTE version 15272 and AERSURFACE version 13016.  Data are available for the five-year period of 2012 to 2016 for all stations except Yuma.  For Yuma, data are available from 2009 to 2013 because substantial one-minute/five-minute data are missing during the most recent years.  For Kingman, Page, Winslow, St. Johns and Safford, five-minute data were used to supplement the one-minute data because monthly one-minute data are missing from June to December 2013.  The ADJ_U* option was used to process all meteorological data |  View Data > 

One-Hour NOModeling Data

ADEQ compiled five-year hourly ozone ambient air quality monitoring data for nine ozone monitors across Arizona.  These hourly ozone data, concurrent with ADEQ's pre-processed meteorological data, may be used in Tier 3 modeling for one-hour NO2. Moreover, ADEQ compiled one-hour NO2 background concentrations for seven monitors in Arizona and one monitor in New Mexico. The background concentrations were calculated  based on 98 percentile of the Seasonal Hour-Of-Day, taking diurnal and seasonal patterns of ambient air quality monitoring data into account | View Data >