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DFE World: Design & the Global Environment
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Air Pollution
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Exercises


 

Central Campus Air Quality Model (CCAQM) Instructions

 

·         Run Conditions

 

 

o      Wind Speed (m/s) - The minimum choice available for CALINE4 (0.5 m/s).  Alternatively, EPA (1992) recommends a value of 1 m/s as the worst-case wind speed.

 

o      Wind Direction (degrees) - should be specified with respect to the chosen Cartesian coordinate system, with zero degrees corresponding to true north. This is the direction the wind is blowing from, measured clockwise in degrees from the north (0 = north, 90 = east, 180 = south, 270 = west).  Most users should opt for the "Worst-Case Wind Angle" choice on the Job Parameters screen.  If "Worst-Case" is selected, CALINE4 does not use this input.

 

o      Wind Direction Std. Dev. (degrees) - The statistical standard deviation of the Wind Direction.  See Table 5 for recommended values.

 

o      Atmospheric Stability Class (1-7) - A measure of the turbulence of the atmosphere.  Values 1 through 7 correspond to the standard definitions for stability class A through E.  Stability class G (or 7) represents the most stable conditions.  See Table for recommendations of worst-case conditions.

 

o      Mixing Height (m) - The altitude to which thermal turbulence occurs due to solar heating of the ground.  Reasonable values for the worst-case mixing height rarely have a significant impact on CALINE4 model results.

 

o      Ambient Temperature (degrees C) - The ambient air temperature significantly affects vehicle CO emissions. A temperature that reflects wintertime conditions should be selected, expressed in degrees Celsius.

 

o      Ambient Pollution Concentration (ppm) - This measure reflects the pre-existing background level of carbon monoxide, expressed in parts per million.  CALINE4 adds the pre-existing and modeled CO concentrations together to determine the total impact at each receptor.  A reasonable ambient concentration of CO is 3 ppm.