1. Natural Background Visibility Feb. 6, 2004 Presentation to VISTAS State Air Directors Mt. Cammerer, Great Smoky Mtn. National Park

2. Natural Conditions – the IMPROVE Equation IMPROVE equation is used in regional haze rules for calculating reconstructed extinction from IMPROVE chemical composition data: Bext =3 * f(RH)*([Ammonium] Sulfate+ [Ammonium] Nitrate)+ 4 * 1.4 x OC+ 1 * SOIL Mass + 0.6 * Coarse Mass + 10 * EC + Rayleigh Scattering The EPA RHR calls for expressing visibility conditions in terms of deciviews (dv) that is defined as: dv = 10 ln (bext/10)

3. Natural Conditions: EPA Default Approach East (mg/m3) Ammonium Sulfate0.23 Ammonium Nitrate0.10 Organic Carbon Mass1.40 Elemental Carbon0.02 Soil0.50 Coarse Mass3.00 The default annual natural levels of PM components in EPA’s guidance (based on values that were developed for the NAPAP by Trijonis,1990) are used in the equation to calculate annual average Natural Conditions 20% worst natural conditions (dv) determined from the annual average 20% Worst (dv) = Annual Average (dv) + 1.28x 3 dv (sites in East)

4. Natural Background Visibility: Policy Considerations VISTAS assumptions must be comparable to EPA and other RPOs Retain defaults for this first SIP? Identify alternative ranges for each Class I area in southeastern US? How/when address non-US transported anthropogenic emissions? Does change in assumptions for 2064 affect reasonable progress goals for 2018?

5. VISTAS Class 1 Area Visibility Targets Worst 20% days 0 5 10 15 20 25 30 35 1988-19921990-19941992-19961994-19981996-20001998-2002 2010 202020302040 2050 20602064 Deciviews 5 year Average 0 10 20 30 40 50 60 70 80 90 Standard Visual Range Miles Everglades Mammoth Cave Median SVR 2018

6. Default vs Alternative Calculations: Does it make a difference in 2018? Natural Background (EPA default) Natural Background (with changes) 2000 2018 YEAR 2064 29.9 dV 20% Haziest Days

7. Extinction (Mm-1) Coarse Soil Organics EC NH 3 NO 3 (NH 4 ) 2 SO 4 Rayleigh Dolly Sods, WV Shenandoah, VA James Rvier Face, VA Mammoth Cave, KY Sipsey, AL Great Smoky Mtns, TN Linville Gorge, NC Swan Quarter, NC Cape Romain, SC Okefenokee, GA Chassahowitzka, FL Everglades, FL Shining Rock, NC Light Extinction on 20% Haziest Days - IMPROVE 1998 - 2001

8. Natural Background Visibility: Potential Changes to Default Calculations for VISTAS Class I Areas Potential change ConfidenceControversyMagnitude 1 Change applied to daily and annual calculations Mm -1 20% haziest days represented by 92 nd percentile, not 90 th HL(+.42 dv) 20% haziest days represented differently than normal distribution LM? Multiplier for Total Organic Carbon mass is >1.4 M L (1.6-1.8) M-H (2.0-2.1) H (+2.8) Decrease extinction efficiency for S, N, or OC to offset increased OC mass MM? decrease 1 Magnitude estimated as high (H), medium (M), or low (L) impact to light extinction in mm -1 on 20% haziest days

9. Potential change ConfidenceControversyMagnitude 1 Change applied to daily and annual calculations Mm -1 Seasalt as NaCl MLM (>+1) Transported non-US anthropogenic Sulfur, Nitrogen MMM (~+1) 1 Magnitude estimated as high (H), medium (M), or low (L) impact to light extinction in mm -1 on 20% haziest days Natural Background Visibility: Potential Changes to Default Calculations for VISTAS Class I Areas

10. Potential changeConfidenceControversyMagnitude Episodic events – How apply to 20% haziest days or annual? How accounted in annual default assumptions? Organic Carbon (OC) gaseous emissions from vegetation: Apr – Oct L-M M-H (+1-5) OC and Elemental Carbon (EC) from “natural” fires events in US L-M L (+<1) Transported non-US anthropogenic Carbon (OC+EC) (including fire) M-LL-M L (?) OC from ocean LML (+<1) Natural Background Visibility: Potential Changes to Default Calculations for VISTAS Class I Areas 1 Magnitude estimated as high (H), medium (M), or low (L) impact to light extinction in mm -1 on 20% haziest days

11. Potential changeConfidenceControversyMagnitude Episodic events – How apply to 20% haziest days or annual? How accounted in annual default assumptions? Asian Dust MLL (<0.5) African Dust MLL (<0.5) Seasalt reaction increases NO3 L-M L (?) Others? 1 Magnitude estimated as high (H), medium (M), or low (L) impact to light extinction in mm -1 on 20% haziest days Natural Background Visibility: Potential Changes to Default Calculations for VISTAS Class I Areas

12. EPRI Recommendations for Refining Natural Background Calculation The table on following slide shows impact of using alternative assumptions taking into account: Background concentrations of ammonium sulfate, ammonium nitrate, OCM and EC as estimated by Dr. Daniel Jacob’s group STI approach to calculate natural visibility for the 20% worst days A factor of 2.0 to convert OC to OCM A varying scattering efficiency for ammonium sulfate and ammonium nitrate using equation developed by STI

13. Impact of using EPRI-recommended approach on concentration reductions* needed by 2018 Class I site All Species Reduction (EPA Default) All Species Reduction (EPRI Approach) Sulfate and Nitrate Reduction (EPA Default) Sulfate and Nitrate Reduction (EPRI Approach) Acadia35%30%44%37% Big Bend34%26%62%49% Boundary Waters32%26%46%33% Grand Canyon28%23%70%>100% # Great Smoky41%35%49%40% Mount Rainier35%23%60%50% *Assuming uniform reductions in anthropogenically caused portion of the baseline concentrations # Sulfate and nitrate concentrations reductions alone will not be sufficient to achieve the first progress goal 15-35 percent lower concentrations reductions needed by 2018 using EPRI’s recommended approach than if use EPA’s default approach

14. VISTAS Recommendations: Feb 6, 2004 Follow up with VISTAS Data Workgroup Evaluate changes in assumptions where agreement among states and stakeholders 92% used to represent 20% haziest days OC multiplied by 1.8 to calculate OC mass Others? Define level of effort to refine estimates seasalt, biogenic, fire, dust, transported non-US Follow up with VISTAS Planning Workgroup Evaluate benefits of control strategies against reasonable progress goals Don’t change the reasonable progress goal for inter- continental transport, but estimate contribution if goal not met in 2018 Coordinate with EPA and other RPOS

15. Jan 2004 Revised 2002 VISTAS Em Inv Feb 2004 MM5 Met runs 6 mo 2002 Apr 2004 Draft “2018” National Inv Sep 2004 Revised 2002 National Inv Mar-Sep 2004 Annual 2002 CMAQ model performance Dec 04 ? “2018” Base Run Apr 2004: DDM in CMAQ May-Oct 2004 “2018” Emissions Sensitivity Runs Sep 2004 “Typical” 2002 Modeling Inv Oct-Dec 2004: Control Strategy Inventories Jan 2005 Phase II “2018” Sensitivity Runs Jan-Jun 2005 “2018” Control Strategy Runs Apr 2004 CART:select episodes July-Dec 2005: Observations Conclusions Recommendations Jan 2005 Interim Future Year Model Runs Dec 2004 Interim Future Year Inventories Emissions, Meteorological, Air Quality Modeling Deliverables State Regulatory Activities Jan-Jun 2004 Define BART sources Jun 2004 Identify BART controls Draft 1/16/04 EPA- approved Modeling Protocol June 2005 Economic Analyses Feb 2004 Em Modeling QA + Fill Gaps Jan 2004 Met modeling protocol Feb 2004 AQ modeling protocol Jan 2004 AQ Phase I wrapup Jan-Mar 2004 Define inv growth and control assumptions Dec 2004 Revised 2002 Base Run (model performance) Oct 2004: Revised “2018” Em Inv Sept 2004 MM5 Met Final Report Dec 2004 “Typical” 2002 Run (compare to “2018” runs) Aug 2004 Natural Background and Reasonable Progress Goals