1. Brief Description of CALPUFF Navajo Nation Environmental Protection Agency

2. CALPUFF Modeling System CALMET :Meteorological Model CALPUFF: Transport & Dispersion Model CALPOST : File Processor POSTUTIL : ammonia background concentrations

3. Visibility Measurement Visibility is measured in deciviews Analogous to the decibel scale for sound Deciviews = 10*ln(bext / 10) Extinction increases with the amount of pollution Lower deciview values represent better visibility Increasing deciview values represent increasingly poor visibility

4. 40 CFR Part 51 Appendix Y BART Guidelines Deciview are estimated using the CALPUFF CALPUFF model includes – SO 2, SO 4, NO x, secondary organic aerosol (SOA), fine particulate matter (PMF), coarse particulate matter (PMC), and elemental carbon (EC). Semi-empirical chemical module – conversion of SO 2 to particulate sulfate and NO x to particulate nitrate – rate dependent on meteorological conditions and background ozone concentration

5. Interagency Monitoring of Protected Visual Environments (IMPROVE) Old IMPROVE or Method 6 equation is: bext = 3 * f(RH) * [sulfate]+ 3 * f(RH) * [nitrate]+ 4 * [organic mass]+ 10 * [elemental carbon]+ 1 * [fine soil]+ 0.6 * [coarse mass]+ 10 10 is for Rayleigh scattering f(RH) is a water growth factor for sulfate and nitrate relative humidity (RH), ranging from 1 at low humidity to 18 at 98% humidity

6. Interagency Monitoring of Protected Visual Environments (IMPROVE) The revised (new) IMPROVE or Method 8 equation is: bext = 2.2 * fS(RH) * [small sulfate] + 4.8 * fL(RH) * [large sulfate]+ 2.4 * fS(RH) * [small nitrate] + 5.1 * fL(RH) * [large nitrate]+ 2.8 * [small organic mass] + 6.1 * [large organic mass]+ 10 * [elemental carbon]+ 1 * [fine soil]+ 1.7 * fSS(RH) * [sea salt]+ 0.6 * [coarse mass]+ Rayleigh scattering (site- specific)+ 0.33 * [NO2 (ppb)]

7. Applications of CALPUFF Long range transport Visibility assessments and Class I area impact studies Criteria pollutant modeling- SIP Secondary pollutant formation and particulate matter modeling