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

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!

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

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

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?

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

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

Aug. 18, 2000 Base Emissions

Emissions Sensitivities

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%

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!