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Source: EPA, User’s Guide for the AERMOD Meteorological Preprocessor (AERMET), http://www.epa.gov/ttn/scram/metobsdata_procaccprogs.htm#aermet. November 2004, 

## D.2.4 Airport Capacity and Configurations 

For dispersion modeling, EDMS/AEDT requires the capacity of runway use configurations as inputs to the Delay and Sequence Module. Configurations represent specific wind flows, cloud ceiling, and visibility conditions. For such configurations, the airfield capacity should established (i.e., the number of departures during which the hourly arrivals are at maximum and the number of arrivals during which the hourly departures are at maximum). The Aviation System Performance Metrics (ASPM) database can be used to establish the hourly capacity of an airport. 84 

## D.2.5 Spatial Allocation 

EDMS/AEDT and AERMOD incorporates specific details on source location (i.e., airport layout and roadway network) and activity variation to develop a spatial representation of each emission source. The locations of emission sources and receptors should be represented in the Universal Transverse Mercator (UTM) coordinate system and the analysis should be centered on the airport reference point. 85 Emission source locations can be determined using airport layout plans, aerial photographs, drawings, maps, available databases, and/or site visits. The location of endpoints can be obtained from AEDT or the FAA’s Airport Master Record. 86 

Other spatial allocation parameters included in an air dispersion modeling analysis include the following: 

• Runway utilization 

• Taxipaths 

• Apron/Gate Assignments 

The percent of time the various runways are used for departures/arrivals are developed distribute the aircraft operations to each runway endpoint. To accommodate EDMS /AEDT and AERMOD, the runway utilization is developed by aircraft size (i.e., small, large and heavy) for each airfield configuration. 

