## Concentration / Setup Run / Pollutant Definition

There are four CONTROL file entries, lines 11(1) through 14(4), that correspond with each line of the pollutant menu shown in the illustration below.

10- Number of different pollutants

Default: 1

Multiple pollutant species may be defined for emissions. Each pollutant is assigned to its own particle or puff and therefore may behave differently due to deposition or other pollutant specific characteristics. Each will be tracked on its own concentration grid. The following four entries are repeated for each pollutant defined.

11(1)- Pollutant four Character Identification

Default: TEST

Provides a four-character label that can be used to identify the pollutant. The label is written with the concentration output grid to identify output records associated with that pollutant and will appear in display labels. Additional user supplied deposition and chemistry calculations may be keyed to this identification string.

12(2)- Emission rate (per hour)

Default: 1.0

Mass units released each hour. Units are arbitrary except when specific chemical transformation subroutines are associated with the calculation. Output air concentration units will be in the same units as specified on this line. For instance an input of kg/hr results in an output of kg/m3. When multiple sources are defined this rate is assigned to all sources unless the optional parameters are present on line 3(1).

13(3)- Hours of emission

Default: 1.0

The duration of emission may be defined in fractional hours. An emission duration of less than one time-step will be emitted over one time-step with a total emission that would yield the requested rate over the emission duration.

14(4)- Release start time: year month day hour minute

Default: [simulation start]

The previously specified hours of emission start at this time. An entry of zero's in the field, when input is read from a file, will also result in the selection of the default values that will correspond with the starting time of the meteorological data file. Day and hour are treated as relative to the file start when month is set to zero.

Temporal or Area Emission Variations

This menu is only designed to input point source emission rates. Unless additional input values are provided in the control file after each emission location, the same rate will apply to all defined point sources for the duration of the emission. When more complex emission scenarios are required, emission data can be read in from a file that defines a diurnal emission cycle for any number of pollutants at any number of locations. If the emission rate is to vary in time beyond one diurnal cycle, there is another input file that can be defined to set a new rate with each emission cycle. In this latter scenario the rate as well as the location may be changed.

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