1. NONROAD Model Sensitivity to Temperature
12/1/2003
Rosa Chi
EAS6792

2. EPA NONROAD Model
Includes the following major emission source categories:
recreational equipment
construction and mining equipment
industrial
lawn and garden
agricultural
commercial
logging
airport ground support
railway maintenance
recreational marine vessels
More than 260 specific equipment types modeled!

3. Emissions Conversion Factors PM Fractions HC Conversions Population
Emission Factors
Activity
Geographic Allocation
Age Distribution
Deterioration
Rated Power
Load Factor
Hours per Year
EF Corrections
Activity Corrections
Growth
Scrappage
Seasonal/ Monthly Corrections
Weekend/ Weekday Corrections
Average Life
Temperature
RVP
Oxygenate
Fuel Sulfur

4. Emissions Calculations
Emissions = (Population) x (Rated Power) x (Load Factor) x (Activity) x (Emission Factor)
(Emission Factor) = (Base EF) * (Temperature Correction Factor) * (Other Factors)

5. Temperature Corrections
Pollutants: HC, CO, NOx
Evaporative Emissions: Ideal Gas Law
4-stroke Exhaust Emissions:
TCF = exp [ A * (Tamb-75) ]
“A” depends on Tamb and pollutant
No corrections for 2-stroke, diesel
How important is spatial resolution?

6. Sensitivity Analysis Scenario
State of Georgia
August 18, 2000
State-wide average, min, max temperatures based on 97 NWS weather stations covering 86 counties.

7. Assumptions Vary temperatures up and down by 10%
Sensitivity = 5 * (E110% - E90%)/E100%
Assume linear!

8. Aug. 18, 2000 Base Emissions

12. Emissions Sensitivities

14. Summary of Results Exhaust Emissions THC CO NOx
Largest % decrease in a single county
-0.2%
-2.3%
-0.4%
Largest % increase in a single county
0.3%
2.0%
1.4%

15. Conclusions Finer spatial temperature resolution not needed Caveats:
May not apply for large temperature ranges
Effect in winter not studied
Shows importance of modeling spatial temperature difference in model as is, not importance of temperature difference in real life!