Development, Maintenance andEvaluation of CALPUFFPresented at:9thConference on Air Quality ModelingOctober 9-10, 2008by:Joseph ScireTRC Environmental Corporation**Model Development Model Development** **• CALPUFF system undergoes continual refinement and development, with new features and productivity** **enhancements. EPA provides no funding for development or maintenance activities.** **• TRC has developed graphical interfaces and visualization tools which are distributed to the pu** **blic without cost** **• Technical developments are made within TRC both with and without external funding** **• EPRI PRIME downwash module • Flexible coordinate transformations** **• MMS updates for coastal applications • VISTAS enhancements** **• Forest Service enhancements • NASA and Forest Service sub-hourly Version 6** **Model Development • Technical developments are also contributed from** **other users and researchers • Hybrid puff-particle version - Switzerland** **• Large-particle settling (volcanic ash) - Italy • Solar radiation effects on canyon sidewalls and te** **rrain shadowing - Italy** **• TRC has implemented procedures to satisfy current regulatory needs without federal funding and** **distributes these codes to the public for free incl uding:** **• EPA BART 98 th** **percentile computations • Proposed 2008 FLM (FLAG) visibility method** **• Processors are continuously updated to accept new or** **revised data formats • TRC has develop interfaces to mesoscale prognostic** **meteorological models such as MM5, WRF, RUC, RAMS and Eta and distributes these codes to the** **public for free. Model Development** **• Graphical User Interfaces (GUIs) –** CALPRO**• Geophysical processors (TERREL, CTGCOMP, CTGPROC, MAKEGEO)** **• Surface meteorological data processor (SMERGE) • Upper air data processor (READ62)** **• Precipitation processors (PXTRACT, PMERGE) –** COORDS**• Converts to/from any of the following Geodetic, UT M, Lambert Conic** **Conformal, Tangential Transverse Mercator, Polar Ster eographic,** **Equatorial Mercator, Lambert Azimuthal Equal Area • Datums (~150 different datums available worldwide, inc** **luding WGS-84, NAD-27, NAD-83)** **–**BUOY**• Processes buoy data and creates SEA.DAT files –** UAMAKE**• Extracts data from a prognostic (e.g., MM5) file to create soundings as** **replacements for missing upper air data Model Development** **• Graphical User Interfaces (GUIs) –** PRTMET**• Produces vector plots, contour plots of meteorologi cal fields** **• Time series files for plotting • Uses Surfer plotting package (Golden Software pack** **age) –** CALVIEW**• Displays vector/contour/3-D perspective plots • Animations** **–**CALWindRose**• Wind rose plotting software • Displays wind roses directly from SURF.DAT, UP.DAT,** **CALMET.DAT or 3D.DAT files** **–**SurfSizer**• Utility working with Surfer to quickly re-size plo ts** **–**SurfExporter**• Utility working with Surfer to quickly export plot s in various formats** **(BMP, JPG, TIF, etc.) and user-specified resolution Model Development** **• Graphical User Interfaces (GUIs) –** SIA Generator**• Develops a radius of concentration values above a threshold** **• Useful for determining the Significant Impact Area ( SIA)** **–**PICtoReport**• Imports image files into PowerPoint or Word • Automatic sizing and centering of each image** **• Works with PNG, BMP, JPG, TIF, GIF and BLN files –** CALPUFF Plot (currently in testing phase)**• Generates KML files from BPIP input files • Enables 3D viewing of building layout in Google Ea** **rth • Useful for QA and display purposes** **•**New:**Ability to overlay concentration isopleths on base map** 

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docket-customerservice@epa.gov**Model Development • Graphical User Interfaces (GUIs)** **–**FEPS2BAEM**• Fire Emission Production Simulator (FEPS) is a Fores t Service model** **that predicts fuel consumption and emissions from wil dfires and** **controlled burns • FEPS2BAEM converts FEPS output data to the CALPUFF** **buoyant area source emissions file format (BAEMARB.DAT)** **–**ScavCoeff**• Estimates size-dependent wet scavenging coefficient s for liquid and** **frozen precipitation • For particulate matter < 20** μ**m diameter –** AER2CAL**• Converts AERMOD output concentration files into CAL PUFF formatted** **concentrations files • Allows use of CALPUFF postprocessing tools with AER** **MOD output • Contour plots, animations, base maps, etc.** **Model Development • Additional processor options and datasets** **– Terrain data options include 30arcsec (900m), 3 arc sec (90 m), 1 arcsec** **(30m) USGS DEMs, SRTM data format, generic data format s** **– Landuse – new option to process NLCD format • Repartitioning of HNO** **3 /NO** **3 (POSTUTIL)** **– Source contribution analysis – Streamlined one-step ALM processing** **– Non-linear chemistry effects (NO 3** **) – Computation of total S and N deposition** **•**No-Observations version of CALMET**– Uses gridded 3-D data fields as initial guess fiel ds** **– Adjusts winds for fine-scale terrain effects on CA LMET grid** **– Allows forecast applications Model Development - CALMET** **•**New interface programs**– WRF – NCEP models: ETA and RUC2** **– RAMS – MM5 (Version 3)** **– enhanced output (3D.DAT, 2D.DAT files) •** SEA.DAT files**created from MM5 model using high resolution sea-su rface** **temperature data •** COARE Algorithms**•**Convective mixing over water**– Maul-Carson (M-C) scheme and Batchvarova-Gryning (B-G ) scheme** **(1994) Model Development - CALPUFF** **• Boundary condition module • Rain hat option on stacks** **• Mass balance/flux tracking options • Horizontal puff splitting** **• NH 3** **as an active species • New turbulence profile option using AERMOD profile** **– Original CALPUFF turbulence parameterization – AERMOD turbulence profiles** **• AERMOD met data options – Option in CALPUFF to read AERMOD met data files** **– Utility to create AERMOD met files from 3-D CALMET output** **Model Development - CALPUFF • Time Step < 1 Hour (CALMET, CALPUFF)** **• Secondary organic aerosol module • Terrain enhancement of precipitation** **• Fogging and icing (cooling towers) – Visible plume lengths** **– Frequency of plume-induced fogging and icing • Turbulence advection** **• Platform downwash • Back trajectory analysis** **Model Development – On-going • Nested grid option** **• Option to name receptor sets and process by recept or group** **• Meteorological evaluation software (METSERIES and METCOMP)** **– Wind rose (graphics completed) – Time series plots** **– Scatter plots – Statistics** **– X-Z cross sections – Standard report** **• Enhanced animation options – Create, name and save animation files for future pla** **ying (completed) – Display of puff movements and growth (on-going)** **Model Maintenance Model Maintenance** **• With few exceptions, all model maintenance is done without contractual funding support** **• Investigate all reported issues. Request detailed error reports and test datasets from user** **• About 75% found to be due to data problems, hardware problems or input errors** **• Bugs are isolated and fixed with detailed updates to** **in-code documentation and version/level journaling • Model Change Bulletin (MCB) updated** **• Updated code(s) run in EPA CALPUFF Update Tool and results sent to EPA** **Model Maintenance CALPUFF MCB History** **No Action February 14, 2008** **MCB-E No Action** **June 27, 2008 MCB-E (Part 2)** **June 29, 2007 Accepted** **December 16, 2005 May 1, 2007** **June 23, 2007 MCB-B** **MCB-C – VISTAS MCB-D** **June, 2006 Accepted** **July 16, 2004 MCB-A** **April 15, 2003 FR Notice** **Official Version**EPA ActionCALPUFF**Note: MCB-C contains all fixes in VISTAS version r eleased August 4, 2006** **Model Maintenance – The Plan • TRC** **– provides developmental model version as a mechanism for quickly evaluating bug-fixes and** **model enhancements • EPA action at periodic intervals** **– reviews bug fixes and considers new options and features** **• accept/recommend new features • suggest changes/modifications** **• Accepted features placed in regulatory recommended option set** **• Other features may be retained for additional test ing,** **or abandoned or not recommended for regulatory use Model Maintenance - Reality** **• Problems with Review Process – Long delay in EPA reviewing bug fixes** **– EPA review of model enhancements on hold • Example Enhancement** **– Surface station data assigned to grid cells using nearest-station in EPA-approved CALMET** **– Surface station data interpolated to grid cells us ing** **1/R 2** **weights in VISTAS CALMET – Nearest-station technique leads to sharp gradients** **– EPA criticizes sharp gradients yet has not considered this enhancement which was in the** **VISTAS code and removed at EPA’s insistence in the current EPA-approved code** **Model Maintenance • Earth Tech/TRC commitments have been** **scrupulously adhered to: – Model maintenance continues to be done by TRC** **without EPA support – Agreement to keep regulatory model unchanged** **on web site – EPA determines “EPA-approved” version** **• What has happened to process? – Changes at EPA in management and staff** **– EPA Modeling Group – some loss of institutional memory and continuity?** **Model Maintenance • EPA presentations at 2007 and 2008 R/S/L Modelers** **Workshops contain misleading statements about CALPUFF, and include examples that do not reflect** **good modeling practice • CALPUFF Regulatory Update (June 2008 R/S/L** **Workshop) – “Lack of adequate documentation”** **• “New MREG option in CALMET not well-documented” • “User’s guide last updated in 2000”** **• “Many important technical details are not document ed,** **except in code” – “serious unresolved technical concerns”** **Model Maintenance • Documentation?** **– 885 pages of detailed technical documentation and user** **guide updates in March 2006 describing MMS changes – 853 pages of documentation in original user guides** **– Compares well in technical detail and content with AERMOD** **documentation • Why should this be known to EPA? MMS project** **changes were the subject of the EPA oversight: – EPA represented on Scientific Review Board for MMS** **project (John Irwin, Modeling Group, OAQPS) – MMS presentation was made at June 2007 EPA R/S/L** **Modelers Workshop. Updated User’s Guides available online since early 2006 (listed in presentation)** **– Multiple references made to MMS reports by TRC to EPA** **during VISTAS model review Model Maintenance** **• Constructive criticism and helpful suggestions are always welcome, but vague references to problems** **without backup and data are not helpful or constructive.** **• CALMET MREG Option? – Option formulated by TRC with EPA review** **– Input file language presents option choices • Unresolved Technical Concerns?** **– Issue was default value for new CALMET input variable. Value resolved to EPA satisfaction (May** **2007) Model Maintenance** **VISTAS CALMET technical enhancements in v5.8 awaiting EPA review** **• Fully interpolated 2D fields for surface-layer temperature and density instead of nearest-station** **selection of surface meteorological data • Use consistent surface-layer stability correction** **profiles throughout • Recognize convective over-water boundary layer** **(instead of using neutral boundary layer formulatio ns** **from OCD) • Use Coupled Ocean Atmosphere Response** **Experiment (COARE) bulk flux model for overwater fluxes in place of older OCD methods** **• Updated convective boundary layer parameterization following Batchvarova and Gryning** **Model Maintenance • EPA CALPUFF studies used in EPA presentations** **have not been open review by TRC or the public • Important for transparency that all modeling files** **on which decisions/memos are based are made** **promptly public – Results presented in public forums rather than** **communicated directly – Modeling and data files not available** **– Lack of constructive criticism with a focus on resolving issues** **Wind Field Bull’s Eye From Bret Anderson (USEPA Region 7)’s presentation** **at the 2007 Regional State Local Modelers Workshop** **“Illustration of meteorological issues – CALMET diag nostic meteorological model”,** **When MM5 does not match the observations** **• Bull’s eye features is a result of MM5 winds not matching observations. Issue may be with** **MM5 or a non-representative observation • Solution:** **– (1) Pure NOOBS mode : MM5 only fields – (2) Pure observation mode** **– (3) Hybrid mode with MM5 as initial guess field, small R1-R2, matching the observations right at the** **stations and MM5 fields away from them – (4) Hybrid mode with poorly selected large R1/R2,** **creating a bull’s eye, with station winds clashing with** **MM5 fields So 3 good ways to run CALMET without creating a sha** **rp discontinuity and 1 bad way, creating a bulls’ eye** **• Sydney Harbor – Summer sea breeze • Local observation at odds with mesoscale** **features • MM5 at 1.33 km resolution** **• 5 surface stations, 1 buoy, 1 upper air station (not used in hybrid)** **• Plots: 40km x 30km ; resolution: 1km How to run CALMET when MM5** **does not match the observations Solution 1: Run in NOOBS** **Solution 2: run in OBS-only Solution 3 : Hybrid with R1<<RMAX1** **R1=1km – RMAX1=20km 4. EPA’s bull’s eye no-solution: hybrid with** **R1>>RMAX1 R1=20km – RMAX1=3km** **AERMOD • And what would AERMOD do in this region?** **• An infinite radius bull’s eye, only matching one s tation and not** **representing observations at any other sites.... Solution for Better EPA and** **Community Input? Establish Science Advisory Committee** **• TRC-organized CALPUFF technical committee • Provide objective, unbiased advice** **• Identify model improvements • Possible Members:** **– EPA – FLMs** **– MMS – PBL Expert** **– Dispersion Modeling Expert – 2-3 Active Users (Consultants or Industry)** **– One public meeting per year via web-link • New web-based user group (or promote existing e-li** **st at Washington (Clint Bowman))** **Model Applicability and Evaluation** **Model Applicability – Near-Field: AERMOD vs. CALPUFF** Overwater turbulence module and TIBLalgorithm to treat coastal fumigationNo coastal TIBL or fumigationalgorithmCoastal effects, fumigationCALPUFF retains previous hoursemissions within domain and evaluatesimpacts from themNot treated. AERMOD has nomemory of pollutants emittedduring previous hoursMass accumulation duringstagnation. Memory?Calm winds treatedNot treated – removed from theanalysisCalm windsFull variability considered whenCALMET meteorological dataset usedNone. Single station wind isapplied over entire modelingdomainHorizontal wind variabilityCALPUFF determines surfaceconditions in each grid cell and appliesit to a puff as it passes that cell.Downwindconditions of each andevery source are evaluated on a puffby-puff basisAERMOD looks upwindofmet.stationin a radius of 1-km tocharacterize turbulence up to 50-km downwindofsourcePolicy on treating surfacevariabilityFull variability – uses 2-D gridLand use variability allowed inwind sectors centered at met.stationSpatial variability of surfacecharacteristicsYesNo – plume extend to infinityCausality effects considered?**CALPUFF AERMOD** **Feature Model Applicability – Complex Terrain** **• EPA indicates AERMOD is suitable for complex terrain permitting applications** **• Main Issues with AERMOD – Use of a single meteorological field to characteri** **ze flow for facility + all background sources** **– Use of surface characteristics**upwind**of meteorological station to characterize** downwind**turbulence of all sources – Causality effects (plume go to infinity each hour)** **– Use of straight-line trajectories Model Applicability – Complex Terrain** **• EPA’s argument that AERMOD is OK in complex flow regimes because only line of** **sight impact matters is flawed for 2 major reasons** **– NAAQS and PSD increments are**cumulative**standards, not single facility standards. Interacting sources matter in assessing** **compliance with the standards. – Non-peak concentrations are important in** **assessing significant contribution above/below the SILs.** **• Facility contribution above the SIL to a violation is** **considered a significant contribution 370 375 380 385 390 395 400 405 410** **UTM East (km) 4730** **4735 4740** **4745 4750** **4755 4760** 

**UTM North (km) 42.8N** **42.9N 112.5W** **112.4W 112.3W** **112.2W 112.1W** **-1 100** **300 500** **700 900** **1100 1300** **1500 1700** **1900 2100** **2300 2500** **2700 2900** **3100 3300** **3500 3700** **3900 4500** **Terrain (m) .** **. UTM Zone: 12** **Datum: WGS-84 Hemisphere: N** **Surface Meteorological Stations (used by Calmet) Upper air radiosonde station (used by Calme)** **Surface and Upper air Station (used by Aermod) 10m Calmet wind field 6 Jan (23h00) - 7 Jan (05h00)** **1993 Wind Vectors (10m) – Complex Terrain with Channeled** **Flow CALPUFF – Cumulative Impacts** **370 375 380 385 390 395 400 405 410 UTM East (km)** **4730 4735** **4740 4745** **4750 4755** **4760**

**U T**  **M N**  **o r**  **t h**  **( k**  **m )** **42.8N 42.9N** **112.5W 112.4W** **112.3W 112.2W** **112.1W -1** **100 300** **500 700** **900 1100** **1300 1500** **1700 1900** **2100 2300** **2500 2700** **2900 3100** **3300 3500** **3700 3900** **4500 Terrain** **Elevation (m)** **. .** **UTM Zone: 12 Datum: WGS-84** **Hemisphere: N INKOM** **HOSP FMC** CALPUFF shows channeling of flow. Background plumesinteract to produce cumulative impacts in valley.**370 375 380 385 390 395 400 405 410 UTM East (km)** **4730 4735** **4740 4745** **4750 4755** **4760**

**U T**  **M N**  **o r**  **t h**  **( k**  **m )** **42.8N 42.9N** **112.5W 112.4W** **112.3W 112.2W** **112.1W -1** **100 300** **500 700** **900 1100** **1300 1500** **1700 1900** **2100 2300** **2500 2700** **2900 3100** **3300 3500** **3700 3900** **4500 Terrain** **Elevation (m)** **. .** **UTM Zone: 12 Datum: WGS-84** **Hemisphere: N AERMOD Impacts – INKOM Source** AERMOD produces straight-line impacts in terrainusing INKOM met. data. Note the lack of channelingof the flow into the NW-SE oriented valley.**INKOM AERMOD – Cumulative Impacts** **370 375 380 385 390 395 400 405 410 UTM East (km)** **4730 4735** **4740 4745** **4750 4755** **4760**

**U T**  **M N**  **o r**  **t h**  **( k**  **m )** **42.8N 42.9N** **112.5W 112.4W** **112.3W 112.2W** **112.1W -1** **100 300** **500 700** **900 1100** **1300 1500** **1700 1900** **2100 2300** **2500 2700** **2900 3100** **3300 3500** **3700 3900** **4500 Terrain** **Elevation (m)** **. .** **UTM Zone: 12 Datum: WGS-84** **Hemisphere: N**AERMOD produces incorrect cross-valley and downvalley impacts for HOSP and FMC sources. Note lackof plume interaction in AERMOD cumulative impacts.**FMC HOSP** **INKOM Model Applicability** **• Coastal case – Sea breeze penetration over portion of** **domain – Relatively simple terrain** **– 3 sources – Most inland source considered as main** **“facility” source (met data based on it) • Demonstrates even in simple terrain,** **spatial variability can be important Sea Breeze Case – July 7, 1988 – 1:00pm LST** **260 280 300 320 340 360 380 400 420 UTM East (km)** **4640 4660** **4680 4700** **4720 4740** **4760**

**UTM North (km) 1** **2 3** **42.0N 42.5N** **43.0N 72.0W** **71.5W 71.0W** **70.5W 70.0W** LandBreezeSeaBreeze**260 280 300 320 340 360 380 400 420 UTM East (km)** **4640 4660** **4680 4700** **4720 4740** **4760**

**UTM North (km) 1** **2 3** **42.0N 42.5N** **43.0N 72.0W** **71.5W 71.0W** **70.5W 70.0W** **Sea Breeze Case – July 7, 1988 – 1:00pm LST 1** **2 3** Direction ofAERMOD Plumes**Comparison of AERMOD Plume Trajectories (Blue Arrow s)** **with CALPUFF Trajectories (Filled Contours) CALPUFF Plumes - filled contours** **Model Applicability • Random plume in AERMOD creates an** **upwind halo around every source that results in concentrations being** **predicted upwind • Can be problematic for** cumulativeimpact assessments**and assessing significant contributions to violations** **• Upwind concentrations can even exceed downwind concentrations and** **SILs in AERMOD -100 -80 -60 -40 -20 0 20 40 60 80 100** **Distance (km) -100** **-80 -60** **-40 -20** **0 20** **40 60** **80 100** 

**D i**  **s t**  **a n**  **c e**  **( k**  **m )** **0.0005 0.001** **0.0025 0.005** **0.01 0.02** **0.04 0.08** **0.16 0.32** **0.64 1.2** **2.4 U(10m) = 4.5 m/s** **M-O L = 9000. m****u* = 0.780 m/s****w* = 0.0 m/s****Zi = 2449 m z0 = 1 m** **Source Wind Direction** **AERMOD Predicted Concentrations Steady wind (4.5 m/s), Neutral stability** AERMOD Mass Fraction Removed FromCoherent Plume to Random Plume**0.0 0.1** **0.2 0.3** **0.4 0.5** **0.6 0.7** **0 10 20 30 40 50 60 70 80 90 100**Distance (km)

Fraction Removed**Light Wind, Convective Steady Wind, Neutral** **-40 -30 -20 -10 0 10 20 30 40 50 Distance (km)** **20 30** **40 50** **60 70** **80 90** **100 110** 

**Distance (km) 0** **1 2** **3 4** **5 6** **7 8** **9 10** **11 12** **13 14** **15 16** **17 18** **19 20** **21 22** **23 24** **25 26** **AERMOD Stable Impingement Tests** **WD=340 deg**Stack**0 50** **100 150** **200 250** **300 350** **400 450** **500 550** **600 650** **700 Terrain Elevation (m)** **-20 -10 0 10 20 Distance (km)** **50 60** **70 80** 

**D i**  **s t**  **a n**  **c e**  **( k**  **m )** **0 2** **4 6** **8 10** **12 14** **16 18** **20 22** **24 26** Stack**Conc. (ug/m3)** **Wind Direction (340 deg.)**Wide area of upwind conc. >>downwind concentrations**AERMOD – Problem: upwind concentrations larger than downwind concentrations** **Spatial Land Use Variability AERSURFACE Users Guide:** **• “Determining effective surface characteristics for the purpose of** **processing meteorological data for use with the AER MOD** **model presents many challenges.” •** “AERMOD is a steady-state plume model which assumesspatially uniform meteorological conditions acrossthemodeling domain for each hour of meteorology, whilelandcover across the domain is typically very heterogeneous.”**• “A sound understanding of the important physical p rocesses** **represented in the AERMOD model algorithms ... and the** **sensitivity of those algorithms to surface characte ristics is** **needed in order to properly interpret the available data and** **make an appropriate determination.” Data Representativeness** **AERMOD Implementation Guide (January 9, 2008) • “... data representativeness can be thought of in** **terms of constructing realistic planetary boundary layer (PBL) similarity profiles and adequately** **characterizing the dispersive capacity of the atmosphere.”** **• “... the determination of representativeness of sit e** **specific data for AERMOD applications should also include an assessment of surface characteristics of** **the measurement and source locations and cannot be based solely on proximity.”** **AERSURFACE Results (1km) AERSURFACE Roughness** **Lengths (m) for June by Wind Direction Sector** **.01 .34** **.11 .10** **Roughness lengths upwind of measurement location characterize** **local boundary layer (Move location 1km East and smooth water disappears** **from characterization) AERMOD Dispersion** **• Surface Roughness for Dispersion Downwind of Each Source** **• Averaged Surface Roughness Upwind of Met. Measurements** **1 km Up to 50** **km Met Location** **Source Location(s) .01** **.01 .34** **.11 .10** **.11 .10** **.34 “** Upwind**” roughness at measurement location determines** downwind**dispersion at source location in AERMOD** **Downwind Roughness (m) for AERMOD Sources** **.34 .11** **.01 .10** **Source B .34** **.11 .01** **.10 Source A** **Roughness distribution near Source A is not appropriate for modeling interacting** **Source B, nor is it appropriate for much of the 50km region around Source A** **AERMOD Sensitivity to Surface Property Processing** **• Current Guidance: 1 km search radius for surface roughness, with upwind sectors determined by the us** **er. Albedo and Bowen ratio determined for a 10km square** **centered at location. • Previous Guidance: 3 km search radius for surface** **roughness, albedo, and Bowen ratio with upwind sect ors** **determined by the user. • Significance of change characterized for actual pe** **rmitting application** **– 4 stacks (2 at 231 m, 3 m and 27 m stack heights) – Nearly 3500 receptors** **– One full year of surface meteorological data (Loui sville** **International Airport - SDF) AERMOD Sensitivity to Surface** **Property Processing -3%** **-39% -43%** **-34% AERSURFACE 1-km Method** **(airport – onsite location) % Change in Peak Concentrations** **-0.3% 103%** **123% 89%** **AERSURFACE 1-km method – previous 3- km method** **at Airport location**Annual24-hr8-hr1-hrAveraging Time**• Switch to AERSURACE with 1-km radius for z0 increa sed maximum** **short term concentration predictions from AERMOD by more than a** **factor of 2 • Using airport roughness instead of onsite roughnes** **s changes reduces AERMOD predicted short term concentrations** **by up to 43% AERMOD Sensitivity to AERMAP** **DATUM Error • EPA comment: Magnitude of changes in concentratio** **ns due to CALPUFF v5.8 were larger than expected** **• All models will be sensitive to changes in the inp ut** **parameters, including changes due to errors. • Example: coordinate transformation corrected in** **AERMAP • Significance of AERMAP changes characterized for a** **n actual permitting application** **– 2 tall stacks (231 m stack height) – 2 short stacks (3 m and 27 m stack height)** **– Nearly 3500 receptors AERMOD Sensitivity to AERMAP** **DATUM Error 27 %** **-96 % -99 %** **-97 % -99 %** **Paired (correct location) % Change in Peak Concentrations** **[ (bad-corrected)/corrected ] 30 %** **1784 % 10246 %** **10980 % 7307 %** **Paired (bad location) 27 %** **43 % 52 %** **7 % 48 %** **Overall Maximum Annual** **24-hr 8-hr** **3-hr 1-hr** **Averaging Time •Large differences frequently result from code chan** **ges •Differences at specific locations (paired in space** **) can be especially sensitive** **Model Sensitivity • All dispersion models are sensitive to** **changes in model inputs • Skill that an experienced, competent** **and objective modeler brings is ability to make appropriate decisions on how a** **model should be run • Regulatory guidance has a role in** **model applications, but cookbook formulas do not work well in many** **cases CALPUFF Model Evaluation** **• Long-range transport – CAPTEX** **field data for long-range transport distances – Inel** **field data for intermediate transport distances – Wyoming** **dataset (long and short range – cumulative impacts) • Short-intermediate distances** **– Kincaid SF 6** **: tracer releases from 187m stack in flat terrain – Lovett SO** **2 : ambient monitoring on ridge near 145m stack in** **Hudson river valley – PRIME** **datasets (building downwash) – Arkadelphia SF** **6 : tracer releases from line source vents (potrooms)** **– Tennessee SO 2** **: 2 years of monitoring of emissions from potrooms and stacks** **– Overwater and coastal datasets (5) • Ventura, Carpinteria, Pismo Beach, Cameron (0.5 – 8** **km) • Oresund (22 - 42 km)** **AERMOD Model Evaluation 9 used in developing/tuning model algorithms** **7 used to develop/test PRIME downwash module common to ISC-PRIME,** **AERMOD, and CALPUFF (PRIME)** **(PRIME) (PRIME)** **(PRIME) (PRIME)** **(PRIME) (PRIME)** **(PRIME) Westvaco** **Prairie Grass Tracy** **Millstone Martin’s Creek** **Lovett Lee (wind tunnel)** **Kincaid SO2 EOCR** **Kincaid SF6 Clifty Creek** **Indianapolis Baldwin** **DAEC Bowline** **Bowline (subset) AGA** **Alaska Independent** **Developmental 17 AERMOD Evaluation Datasets** **Model Evaluation AERMOD (non-PRIME) Developmental Datasets** **Yes Yes** **Yes Yes** **Yes**OnsiteSigmaW**0.89 (1hr) 1.03 (3hr)** **1.01 (24hr) 0.85 (annual)** **0.98 (3hr) 0.94 (24hr)** **0.30 (annual) 0.77 (1hr)** **1.11 (1hr)**Modeled/ObservedRHC (EPA)**0.46 m release** **145 m Stack 187 m Stack** **187 m Stack 84 m Stack** SourceType(s)OnsiteSigmaThetaMultipleSourceFacilitiesTerrainLandUseSite**Yes None** **Flat Rural** **Prairie Grass (SO2)** **Yes None** **Complex Rural** **Lovett (SO2)** **Yes None** **Flat Rural** **Kincaid (SO2)** **Yes None** **Flat Rural** **Kincaid (SF6)** **Yes None** **Flat Urban** **Indianapolis (SF6)** **Model Evaluation AERMOD (non-PRIME) Independent Evaluation Datasets** **Yes Yes** **No No** **No**OnsiteSigma-W**1.06 (3hr) 1.07 (24hr)** **1.59 (annual) 1.04 (1hr)** **1.12 (3hr) 1.78 (24hr)** **0.78 (annual) 1.05 (3hr)** **0.67 (24hr) 0.54 (annual)** **1.24 (3hr) 0.97 (24hr)** **0.97 (annual)**Modeled/ObservedRHC (EPA)**183 m Stack 91 m Stack** **122 m to 183 m Stacks** **Three 208 m Stacks** **Three 184 m Stacks** SourceType(s)OnsiteSigma-ThetaMultipleSourceFacilitiesTerrainLandUseSite**Yes None** **Complex Rural** **Westvaco (SO2)** **Yes None** **Complex Rural** **Tracy (SF6)** **Yes None** **Complex Rural** **Martin’s Creek (SO2)** **No None** **Half of Stack Ht.** **Rural Clifty Creek** **(SO2) No** **None Flat** **Rural Baldwin** **(SO2) Model Evaluation** **AERMOD (PRIME) Datasets No** **No No** **No Yes** **No**OnsiteSigmaW**0.51 (neutral) 2.50 (stable)** **None 64.8 m** **stack Flat** **“Rural” Lee (wind** **tunnel) 1.72 (1hr)** **Yes None** **Rooftop? Flat** **Rural EOCR** **(SF6) 0.44 (46 m)** **1.32 (29 m) 0.69 (46 m)** **0.25 (24 m) 0.51 (1m)** **1.14 (1hr) 1.43 (24hr)** **1.06(1hr) 0.92 (1hr)** Modeled/ObservedRHC (EPA)**48m and 29m stacks** **1 m, 24m & 46m** **rooftops Two 87 m** **Stacks 39 m Stack** **10-25 m Stack** SourceType(s)OnsiteSigmaThetaMultipleSourceFacilitiesTerrainLandUseSite**No None** **Flat Coastal** **Millstone (SF6)** **Yes None** **Flat Rural** **DAEC (SF6)** **No None** **Flat Rural** **Bowline Point (SO2)** **Yes None** **Flat Rural** **Alaska (SF6)** **No None** **Flat Rural** **AGA (SF6)** **Model Evaluation Number of building downwash studies with very** **long buildings 0** **Number in coastal locations, but not a fumigation scenario due to downwash** **(PRIME building downwash dataset) 1** **Number in complex terrain involving multi-facility impacts** **0 Number involving cumulative impact assessments** **0 17 AERMOD Evaluation Datasets** **•AERMOD has not been evaluated for use in assessing design** **concentration limits arising from interacting facil ities, especially those in** **complex geographic areas •Evaluation datasets include evidence of underpredi** **ction Model Evaluation** AERMOD Results for Kincaid SF6 Tracer Dataset**• Arc-maximum results (best if samplers capture maxi mum)** **• Kincaid SF6 distributed in Model Validation Kit (M VK) used in** **“Harmonisation of Atmospheric Dispersion Modelling fo r Regulatory** **Purposes” workshops • MVK includes Quality Index (QI) values established** **for subset of the data – QI=0: disregard value** **– QI=1: most probably not the maximum value – QI=2: identified value may be near a local maximu** **m – QI=3: identified value is a well-defined maximum** **0.64 (underprediction) MVK Subset for QI=3** **0.68 (underprediction) MVK Subset for QI=2 or 3** **0.77 (underprediction) EPA (all data?)** **Modeled/ Observed RHC Kincaid SF6 Dataset** **Model Evaluation SO** **2 Evaluation – Tennessee Smelter** **• SO 2** **measured upwind and 300m downwind of facility • Primary sources: 4 potrooms (line sources), 4 bank** **s of scrubber stacks (point sources)** **• Two years of data evaluated as part of 1981 BLP ev aluation which** **resulted in BLP acceptance as a**Guideline Model**• Simulations with BLP, AERMOD and CALPUFF**114.2116.2AERMOD19.617.1BLP18.515.8CALPUFF138Observed19771976Units: (μg/m3)**Observed vs Predicted Q-Q Plots – 1977 (1-hr Average SO** **2 Concentrations)** **60 70** **80 90** **95 98** **99 99.8** **99.9 99.99** **99.999 10** **20 30** **40 50** **60 70** **80 90** **100 200** **300 400** **500 600** **700 800** **900 1000** **1100 1200** **1300**Cumulative Frequency (%) 

# Concentrations ( μ g/m 3 

# )ObservationsAERMODBLPCALPUFF**Overwater Evaluation Datasets • OCD datasets (4 datasets)** **– Ventura, Carpinteria, Pismo Beach, Cameron – Test of overwater dispersion over 4-8 km range exc** **ept for Carpinteria and Gaviota (<1km)** **– Both stable and unstable conditions • Oresund Experiment** **– Tracer experiments across 20 km-wide strait of Ore sund** **between Denmark and Sweden – Tracer released at height of 95m or 115m** **– Transport distances to monitors: 22-44 km Cameron, Carpinteria, Pismo Beach, Ventura** **All CALMET Configurations with CALPUFF Configuratio n A** CALPUFF Configuration(Modeled Sigma-v >0.37 m/s)A -- Modeled Iy, CALPUFF Turbs, Draxler FyB -- Observed Iy, CALPUFF Turbs, Draxler FyE -- Modeled Iy, AERMOD Turbs, Draxler FyF -- Observed Iy, AERMOD Turbs, Draxler FyC -- Modeled Iy, CALPUFF Turbs, Variable TLyD -- Observed Iy, CALPUFF Turbs, Variable TLyG -- Modeled Iy, AERMOD Turbs, Variable TLyH -- Observed Iy, AERMOD Turbs, Variable TlyCALMET Configurationc0 – OCD overwater BL parameter modulec10d – COARE module (standard “deep water”)c10s – COARE module with shallow water adj.c11 – COARE module with wave option 1c12 – COARE module with wave option 2OCD5 with Modeled Iy (Sigma-v >0.37 m/s)OCDCALPUFF**0.66 0.54** **OCD5 0.84** **0.62 CALPUFF** **(AERMOD Turbulence Profile) 0.83** **0.60 CALPUFF** **(CALPUFF Turbulence Profile)**CorrelationFraction withinfactor of 2Observed Iy**0.71 0.54** **OCD5 0.85** **0.67 CALPUFF** **(AERMOD Turbulence Profile) 0.84** **0.66 CALPUFF** **(CALPUFF Turbulence Profile)**CorrelationFraction withinfactor of 2Modeled IyFactor of 2 and Correlation statistics**310 320 330 340 350 360 370 380 390 UTM East (km) Zone 33N, Datum: EUR-M** **6140 6150** **6160 6170** **6180 6190** **6200 6210** **6220**

**UTM North (km) Zone 33N, Datum: EUR-M Gladsaxe** **Barseback Snow/Ice** **Tundra Barren** **Wetland Water** **Forest Range** **Agriculture Urban/Built-Up** **Land Use 10** **15 20** **25 30** **35 40** **45 50** **55 60** **65 70** **75 80** **85 90** **95 100** **. .** **. .** **Strait of Oresund Denmark** **Sweden Sampler Locations** **Tracer Releases Terrain Contour 25m** **Oresund**CALMET - CALPUFF Configuration-Zi1 – No Turb Advection, Maul-CarsonMixing Ht-Zi1OW – No Turb Advection, Maul-CarsonMixing Ht , Obs Overwater-Zi2 – No Turb Advection, BatchvarovaGryning Mixing Ht-Zi1OW – No Turb Advection,Batchvarova-Gryning Mixing Ht ,Obs Overwater-800Zi1 –Turb Advection (800s),Maul-Carson Mixing Ht-800Zi1OW –Turb Advection (800s),Maul-Carson Mixing Ht ,Obs Overwater-800Zi2 –Turb Advection (800s),Batchvarova-Gryning Mixing Ht-800Zi1OW –Turb Advection (800s),Batchvarova-Gryning Mixing Ht ,Obs OverwaterNo turbulenceadvectionWith turbulenceadvection**0 0.2** **0.4 0.6** **0.8 1** **1.2 1.4** **1.6 1.8** **2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2** Bridger IMPROVE [SO4]. Units: ug/m **3 of SO4

CALPUFF Predicted [SO4]. Units: ug/m**3 of SO4**CALPUFF PERFORMANCE PREDICTING SO 4** **W/ BCs and ALM (BRIDGER IMPROVE SITE) 2 x overprediction** **2 x underprediction prediction =** **observations**IMPROVE Aerosol Observations**0 0.1** **0.2 0.3** **0.4 0.5** **0.6 0 0.1 0.2 0.3 0.4 0.5 0.6** Bridger IMPROVE [NO3]. Units: ug/m**3 of NO3

CALPUFF Predicted [NO3]. Units: ug/m**3 of NO3**CALPUFF PERFORMANCE PREDICTING NO 3** **W/ BCs and ALM (BRIDGER IMPROVE SITE) 2 x overprediction** **2x underprediction prediction =** **observation OBSERVED AND PREDICTED SO** **4, NO** **3 and SO** **2 (ug/m** **3 )** **90% .207** **.172 .585** **.366 SO** **2 78%** **.081 .082** **.0922 .0978** **NO 3** **94% .248** **.286 .492** **.453 SO** **4 Within** **2x Pred** **SD Obs** **SD Pred** **Mean Obs** **Mean Species** **OBSERVED AND PREDICTED B ext** **(Mm -1** **) BRIDGER TRANSMISSOMETER SITE** **- -** **7.2 5.5** **4.6 Standard** **Deviation -0.030** **-0.017 24.7** **22.5 23.2** **Mean Fractional** **Bias Method 6** **Fractional Bias** **Method 2 Obs** **CALPUFF Method 6** **CALPUFF Method 2** **Variable OBSERVED and PREDICTED ANNUAL WET S** **and N DEPOSITION (kg/ha/yr) AT NADP SITES 0.72** **0.73 Gypsum** **S 1.24** **1.18 Gypsum** **N 0.79** **0.97 South Pass** **S 1.28** **1.43 South Pass** **N 0.83** **1.11 Sinks Canyon** **S 1.36** **1.34 Sinks Canyon** **N 0.69** **0.75 Pinedale** **S 1.17** **0.99 Pinedale** **N Predicted** **Wet Flux Observed** **Wet Flux Site** **Specie s** **Model Evaluation Summary • AERMOD has been shown to perform well in certain** **circumstances but has shown underprediction in several of the EPA datasets.** **• No evaluation data presented by EPA for cumulative impacts assessments or for upwind impacts predicted** **by random plume, or multi-source impacts • Most evaluations method different from typical** **permitting study (i.e., observed turbulence rather than** **predicted turbulence) • AERMOD model formulation makes it unsuitable for** **many non-steady-state situations Consistency vs. Accuracy** **Paragraph 1(d) of the**Guideline**: “The model that most accurately estimates concentra** **tions in the area of interest is always sought. However, it is clear from the ne** **eds expressed by the States and EPA Regional Offices, by many industries and trade** **associations, and also by the deliberations of Congress, that** consistency in the selection and application ofmodels and data based should be sought, even in case-by-case analyses**. Consistency ensures that air quality control agenci** **es and the general public have a common basis for estimating pollutant concentration** **s, assessing control strategies and specifying emission limits.** Such consistency is not, however, promoted at theexpense of model and data base accuracy**. The**Guideline**provides a consistent basis for selection of the model accurate models and data** **bases for use in air quality assessments.”** **Summary • AERMOD should not automatically be preferred over** **CALPUFF in applications involving non-steady-state application** **• AERMOD has significant issues with cumulative impacts** **• AERMOD sensitive to specification of land use and surface properties may involve substantial error** **associated with its inability to vary surface prope rties** **appropriately for the facility source and especiall y** **background sources. • The intent of the GAQM should be followed to allow** **CALPUFF use wherever complex flow or non-steady state conditions are important**