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1、Projected Visibility Changes andSignificance Calculations using theWRAP CMAQ Modeling ResultsWRAP Regional Modeling Center (RMC)University of California at Riverside, CE-CERTENVIRON International CorporationPresents:/slides/ralph/RPO Modeling apr2302.pptProjecting Visibility ChangesKey to Regional H
2、aze Rule (RHR)Must show visibility progress in Section 308 SIPs that meet targetsNeed to project visibility improvements in Section 309 SIPs (no specific targets)EPA Draft Guidance uses models in a relative sense to estimate changes in visibility from 2008 to 2018 for Section 308 SIPsPresents:/slide
3、s/ralph/RPO Modeling apr2302.pptVisibility Significance CalculationRegional Haze Rule (RHR) Section 309 Requirements:Determine whether emissions from Mobile Sources or Road Dust contribute “significantly” to visibility impairment at any of the 16 Class I areas on the Colorado PlateauIf either Mobile
4、 Sources or Road Dust are found to contribute “significantly”, then:Mobile Sources: emissions budgets and tracking system must be establishedRoad Dust: “necessary and appropriate emissions management strategies” must be implementedPresents:/slides/ralph/RPO Modeling apr2302.pptProposed Procedures fo
5、r Projecting Visibility Improvements/Significance CalculationsBased on:Recommendations from the WRAP Mobile Sources Forum Draft June 10, 2002 documentEPAs Draft Guidance for showing visibility progress as part of the RHR (several documents)Availability of visibility measurements and modeling results
6、1996 Baseline Measurements and Estimates2018 Projected EstimatesDiscussions among WRAP participantsPresents:/slides/ralph/RPO Modeling apr2302.pptWRAP Mobile Source Forum (06/10/02)Proposed Cumulative “Significance” TestApply to all Mobile Source or Road Dust emissions in the 9 transport statesSigni
7、ficance Metric = Percent change in extinction over a clean natural background for worst days, Bext ( dv/10)If Bext 10% ( dv 5% threshold is used for individual urban area or state/reservation.If Bext 10% ( dv 1): Bext 1% threshold is used, unless region is found to be in the lowest 20% of contributi
8、onsPresents:/slides/ralph/RPO Modeling apr2302.pptEPA Draft Guidance for Showing Progress as part of the Regional Haze RuleProgress based on changes in extinction for the mean of the Worst 20% (W20) and Best 20% (B20) observed visibility daysModeling results are used in a relative basis using Relati
9、ve Reduction Factors (RRFs), the ratio of future-year to base-year model estimates, to scale the observed visibilityRRFs are applied on a species-by-species basisRRFs are estimated for each Class I areaPresents:/slides/ralph/RPO Modeling apr2302.pptAvailability of WRAP Modeling Results1996 Base Case
10、 and 2018 Base Case and Emission Control Scenarios - No 2003 Base CaseSubstitute 1996 (need 1996 No Mobile/Road Dust scenarios)2018 No Mobile Sources/Road Dust Scenarios included all states/reservationsNeed to redo for just 9-state transport regionNo Mobile Sources was On-Road Mobile Sources onlyNee
11、d to include Non-Road Sources1996 Baseline Year - Not all Class I Areas have measurementsNeed to perform IMPROVE site to Class I area mappingPresents:/slides/ralph/RPO Modeling apr2302.pptProjecting Future-Year Visibility Changesusing RRFs (Scaled Modeling Results)Scale observed 1996 concentrations
12、using modeling resultsSeparate for each Class I AreaSeparate for each species (SO4, NO3, OC, EC, Soil, and CM)Calculated based on the mean of the Worst 20% (W20) and Best 20% (B20) observed visibility days during 1996e.g., SO42018 = SO4Obs_1996 x (SO4Model _2018/SO4Model_1996)Presents:/slides/ralph/
13、RPO Modeling apr2302.pptProjecting Future-Year Visibility ChangesCalculate RRFs for Each IMPROVE speciesSO4 sulfate, ammonium sulfate SO4(NH4)2NO3nitrate, ammonium nitrate NO3NH4OC organic compound/ matter OC, OMEC elemental carbon SootPMFother fine particulates ( 10% ?Presents:/slides/ralph/RPO Mod
14、eling apr2302.pptProjecting Future-Year Visibility Changes16 Class I Areas on the Colorado PlateauOther Class I Areas in 9-State Transport Region, except CaliforniaCalifornia Class I areasProject visibility changes from 1996 to 2018 Analyze differences in visibility between 2018 Emission Scenarios (
15、Is SO2 Annex better than Command & Control w/ Uncertainty?)Presents:/slides/ralph/RPO Modeling apr2302.ppt Projecting Visibility Changes - CAVEATS Emission UncertaintiesNo wind blown dust = Cant use RRFs for No Road Dust Scenario= Need to set RRFCM = 1.0Ammonia, etc.Modeling UncertaintiesWinter nitr
16、ate overestimationMore a Best 20% than Worst 20% problemObserved worst case days may not be modeled worst case days = Conservative Results for Worst 20% days?Presents:/slides/ralph/RPO Modeling apr2302.pptGrand Canyon NP Progress - Worst 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.pptGrand C
17、anyon NP Progress - Best 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.pptProjection of Visibility Changes - Best 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.pptProjection of Visibility Changes - Worst 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.ppt2018 Results 16 Class I Areas
18、 - Best 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.ppt2018 Results 16 Class I Areas - Worst 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.pptSO2 Emission Differences 2018 SO2 Annex Milestone vs. Command & Control w/ UncertaintyPresents:/slides/ralph/RPO Modeling apr2302.ppt2018 Result
19、s Other Class I Areas - Worst 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.ppt2018 Results Other Class I Areas - Worst 20% DaysPresents:/slides/ralph/RPO Modeling apr2302.pptNo On-Road Mobile Source Emissions SignificanceScaled W20 Modeling Results using RRFsPresents:/slides/ralph/RPO Modelin
20、g apr2302.pptRoad Dust Emissions Significance TestCan not use model RRFs approach to scale observed PM concentrationsCoarse Mass (CM) and Soil IMPROVE measurements include wind blown dust that is not included in the inventoryIMPROVE measured CM and Soil include local sources that are subgrid-scale t
21、o the model (36-km)For a sensitivity calculation, used absolute model changes in extinction from 2018 Base Case and 2018 No Road Dust scenariosPresents:/slides/ralph/RPO Modeling apr2302.pptRoad Dust Emissions Significance TestUsing W20 Absolute Model Results (No RRFs)Presents:/slides/ralph/RPO Mode
22、ling apr2302.pptSummary of Projected Future-Year Changesin Visibility from 1996 to 2018Class I areas on the Colorado PlateauBest 20%: Improvements in 9 out of 16 Areas (56%)Worst 20%: Improvements in 12 out of 16 Areas (75%)Other Class I Areas in 9-State Region (Less CA)Best 20%: Improvements in 24
23、out of 40 Areas (60%)Worst 20%: Improvements in 29 out of 40 Areas (73%)California Class I AreasBest 20%: Improvements in 17 out of 29 Areas (57%)Worst 20%: Improvements in 23 out of 29 Areas (79%)Presents:/slides/ralph/RPO Modeling apr2302.pptSummary of Visibility Benefits of 2018 SO2 Annex Milesto
24、ne vs. Command and Control w/ UncertaintyClass I areas on the Colorado PlateauBest 20%: The same or better in all 16 Class I AreasWorst 20%: The same or better in 15 out of 16 Class I Areas (exception is Petrified Forest)Other Class I Areas in 9-State Region (Less CA)Best 20%: The same or better in
25、39 of 40 Class I Areas (exception is Chiricahua Wilderness)Worst 20%: The same or better in 39 of 40 Class I Areas (exception is Eagles Nest Wilderness) California Class I AreasBest and Worst 20%: The same or better in all 29 Areas Presents:/slides/ralph/RPO Modeling apr2302.pptMobile Source and Roa
26、d Dust Significance using Proposed Cumulative Significance ThresholdPreliminary Mobile Source Sensitivity for 2018Need to redo adding Non-Road Sources and limit to just 9-state transport regionFor just On-Road Mobile, Bext ranges from 3.6% to 8.1% (proposed threshold Bext 10%)Adding Non-Road sources will likely exceed 10%Preliminary Road Dust Sensitivity for 2018Missing wind blown dust, so used absolute modeling resultsNo Road Dust change in extinction ranges from 0.8% to 3.1% at 16 Class I AreasPresents:/slides/ralph/RPO Modeling apr2302.ppt
