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Appendix E-1b
Regional Haze Modeling for Southeastern VISTAS II
Regional Haze Analysis Project
Final Modeling Protocol Update and Addendum
August 31, 2020
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Regional Haze Modeling for Southeastern
VISTAS II Regional Haze Analysis Project
Final Modeling Protocol
Update and Addendum to the Approved Modeling Protocol for
Task 6.1 (June 2018)
Prepared for:
SESARM, Inc.
205 Corporate Center Dr., Suite D
Stockbridge, GA 30281-7383
Under Contract No. V-2018-03-01
Prepared by:
Alpine Geophysics, LLC
387 Pollard Mine Road
Burnsville, NC 28714
and
Eastern Research Group, Inc.
1600 Perimeter Park Dr., Suite 200
Morrisville, NC 27560
Final - August 31, 2020
Alpine Project Number: TS-527
ERG Project Number: 4133.00.006
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TITLE and APPROVAL SHEET
Modeling Protocol Plan for
Southeastern VISTAS II Regional Haze Analysis Project for
SESARM (Final)
This Modeling Protocol is approved by the undersigned and effective on the latest date signed by
any party. The organizations implementing the project are Eastern Research Group, Inc. (ERG)
and Alpine Geophysics, LLC (Alpine).
8/31/2020
Regi Oommen – ERG Program Manager and Technical Project Coordinator Date
8/31/2020
Gregory Stella – Alpine Subcontract Manager Date
8/31/2020
John Hornback – SESARM Executive Director Date
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Contents
Page
1.0 INTRODUCTION ............................................................................................................1
1.1 Overview ...............................................................................................................1
1.2 Study Background .................................................................................................3
1.2.1 Natural and Current Base Model Period DV Values at the VISTAS
Class I Areas .............................................................................................6
1.2.2 Purpose ......................................................................................................7
1.3 Lead Agency and Principal Participants ...............................................................7
1.4 Related Regional Modeling Studies......................................................................7
1.4.1 EPA Preliminary 2028 Regional Haze Modeling .....................................7
1.4.2 Maine Department of Environmental Protection Tracking
Visibility Progress 2004-2016 ..................................................................9
1.5 Overview of Modeling Approach .......................................................................10
1.5.1 Episode Selection ....................................................................................10
1.5.2 Model Selection ......................................................................................10
1.5.3 Base and Future Year Emissions Data ....................................................11
1.5.4 Emission Input Preparation and QA/QC.................................................11
1.5.5 Meteorology Input Preparation and QA/QC ...........................................11
1.5.6 Initial and Boundary Conditions Development ......................................11
1.5.7 Air Quality Modeling Input Preparation and QA/QC .............................12
1.5.8 Model Performance Evaluation ..............................................................12
1.5.9 Diagnostic Sensitivity Analyses .............................................................12
1.5.10 Future Year Significant Contribution Modeling .....................................12
1.6 Project Participants and Contacts........................................................................12
1.7 Communication ...................................................................................................13
1.8 Schedule ..............................................................................................................13
2.0 MODEL SELECTION....................................................................................................16
3.0 EPISODE SELECTION .................................................................................................20
4.0 MODELING DOMAIN SELECTION ...........................................................................21
4.1 Horizontal Domains ............................................................................................21
4.2 Vertical Modeling Domain .................................................................................22
5.0 DATA AVAILABILITY ................................................................................................23
5.1 Emissions Data....................................................................................................23
5.2 Ambient Air Quality Observations .....................................................................23
5.3 Meteorological Data............................................................................................23
5.4 Ozone Column Data ............................................................................................24
5.5 Photolysis Rates ..................................................................................................24
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5.6 Land Use .............................................................................................................24
5.7 Initial and Boundary Conditions Data ................................................................24
6.0 MODEL INPUT PREPARATION PROCEDURES ......................................................27
6.1 Meteorological Inputs .........................................................................................27
6.1.1 WRF Model Science Configuration ........................................................27
6.1.2 WRF Input Data Preparation Procedures ................................................27
6.1.3 WRF Model Performance Evaluation .....................................................27
6.1.4 WRFCAMx/MCIP Reformatting Methodology .....................................28
6.1.5 Windowing from EPA 12US2 to VISTAS_12 .......................................28
6.2 Emission Inputs ...................................................................................................28
6.2.1 Available Emissions Inventory Datasets ................................................28
6.2.2 2011 Base Year Emissions......................................................................29
6.2.3 2028 Projection Year Emissions .............................................................29
6.3 Emissions Processing ..........................................................................................32
6.3.1 QA/QC of CAMx-Ready Emission Files ...............................................34
6.4 Photochemical Modeling Inputs .........................................................................35
6.4.1 CAMx Science Configuration and Input Configuration .........................35
6.4.2 VISTAS_12 Boundary And Initial Conditions .......................................37
6.4.3 VISTAS_12 Ozone Column ...................................................................37
6.4.4 Photolysis Rates ......................................................................................37
6.4.5 CAMx Land Use .....................................................................................37
6.5 EPA 2011 and 2028 Base Case Confirmation ....................................................38
6.5.1 Differences Between EPA And VISTAS Simulations ...........................38
6.5.2 Confirmation Methodology ....................................................................38
7.0 MODEL PERFORMANCE EVALUATION .................................................................40
7.1 Model Performance Evaluation ..........................................................................40
7.1.1 Overview of EPA Model Performance Evaluation
Recommendations ...................................................................................40
7.1.2 VISTAS II Calculated Model Evaluation Statistics................................41
7.1.3 Model Performance Evaluation For Weekly Wet And Weekly Dry
Deposition Species ..................................................................................43
7.2 Performance Goals and Benchmarks ..................................................................44
7.2.1 Diagnostic Evaluation .............................................................................46
8.0 AREA OF INFLUENCE ................................................................................................47
9.0 FUTURE YEAR MODELING .......................................................................................56
9.1 Regional Haze Rule Requirements .....................................................................56
9.2 Future Year to be Simulated ...............................................................................56
9.3 Future Year Baseline Air Quality Simulations ...................................................56
9.4 Calculation of 2028 Visibility .............................................................................57
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9.5 Comparison to Regional Haze “Glidepath” ........................................................59
10.0 PSAT SOURCE APPORTIONMENT ...........................................................................60
10.1 Process for Creating PSAT Contributions for Class I Areas ..............................61
11.0 MODELING DOCUMENTATION AND DATA ARCHIVE.......................................64
12.0 REFERENCES ...............................................................................................................65
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TABLES
Table 1-1. VISTAS Region Federal Class I Area List.....................................................................4
Table 1-2. Natural Conditions and Base Year Deciview (dv) Values on the 20% Clearest and
20% Most Impaired Days at each VISTAS Class I Area for the Base Model Period
(2009-2013)..........................................................................................................................6
Table 1-3. Key Participants and Contact Information for the VISTAS II Modeling Study ..........13
Table 1-4. Initial Key Deliverables and Dates for the VISTAS II Modeling Through the 2028
Source Apportionment Reporting ......................................................................................14
Table 4-1. VISTAS II Modeling Domain Specifications ..............................................................22
Table 4-2. WRF and CAMx Layers and Their Approximate Height Above Ground Level .........22
Table 5-1. Overview of Routine Ambient Data Monitoring Networks .........................................26
Table 6-1. VISTAS II Simulation Periods .....................................................................................36
Table 6-2. CAMx Simulations for the VISTAS II Project ............................................................36
Table 7-1. Fine Particulate Matter Performance Goals and Criteria .............................................45
Table 7-2. Species Mapping from CAMx_6.40 into Observation Network ..................................46
Table 8-1. IMPROVE Monitors in the VISTAS_12 Domain........................................................48
Table 8-2. Representative IMPROVE Monitor for Each VISTAS Class I Area ...........................51
Table 9-1. SMAT-CE Settings for 2028 Visibility Calculations ...................................................58
Table 9-2. Matching of CAMx_6.40 Raw Output Species to SMAT Input Variables ..................59
Table 10-1. Matching of CAMx Raw Output Species to SMAT Input Variables .........................60
Table 10-2. Matching of “Bulk Raw Species”, PSAT Output Species, and SMAT Input
Variables ............................................................................................................................61
Table 10-3. Tagged Contribution Calculation Example ................................................................62
FIGURES
Figure 1-1. VISTAS Region Class I Areas. .....................................................................................5
Figure 4-1. Map of 12km CAMx Modeling Domains. VISTAS_12 Domain Represented as
Inner Red Domain. .............................................................................................................21
Figure 6-1. Emission Processing Paths ..........................................................................................33
Figure 8-1. IMPROVE Monitor Locations and Starting Points for HYSPLIT Trajectories in
the VISTAS 12km Domain ................................................................................................49
Figure 8-2. IMPROVE Monitor Locations and Starting Points for HYSPLIT Trajectories in
the VISTAS States .............................................................................................................50
Figure 8-3. Example EWRT Calculations .....................................................................................54
Figure 8-4. Example (Q/d)*EWRT Calculations...........................................................................55
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ABBREVIATIONS / ACRONYM LIST
3DVAR Three-dimensional variational
AFWA Air Force Weather Agency
AGL Above ground level
AL Alabama
ARW Advanced research WRF
AIRMoN Atmospheric Integrated Research Monitoring Network
Alpine Alpine Geophysics, LLC
AMET Atmospheric Evaluation Tool
AoI Area of Influence
AQS Air Quality System
ARL Air Resources Laboratory
BC Boundary conditions
BEIS Biogenic Emissions Inventory System
bext Beta extinction
BNDEXTR Program used to extract boundary conditions
CAIR Clean Air Interstate Rule
CAMD Clean Air Markets Division
CAMx Comprehensive Air Quality Model with Extensions
CASTNET Clean Air Status and Trends Network
CB6r4 Version 6 Revision 4 of the Carbon Bond chemical mechanism
CCRS Coarse PM species (CAMx PM species)
CEM Continuous Emissions Monitoring
CFR Code of Federal Regulation
CIRA Cooperative Institute for Research in the Atmosphere
Cl Chorine
CMAQ Community Multiscale Air Quality
CMV Commercial marine vessel
CO Carbon monoxide
CONUS Continental United States
CPRM Coarse PM
CSAPR Cross-state Air Pollution Role
CSN Chemical Speciation Network
CWT Concentration weighted trajectory
d Distance
DJF December, January, and February
dv Deciview
EC Elemental carbon
EDAS Eta data assimilation system
EF Emission factor
EGU Electric generating unit
EIS Emission Inventory System
EPA United States Environmental Protection Agency
ERG Eastern Research Group, Inc.
ERTAC Eastern Regional Technical Advisory Committee
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EWRT Extinction-weighted residency time
f(RH) Monthly relative humidity function
FAA Federal Aviation Administration
FCRS Crustal fraction of PM
FIPS Federal Information Processing Standard
fL(RH) Monthly relative humidity function associated with large size distributions
FLM Federal Land Manager
FL Florida
FPRM Fine Other Primary (diameter ≤2.5 µm)
FR Federal Register
FSL Forecast Systems Laboratory
fs(RH) Monthly relative humidity function associated with small size distribution
fss(RH) Monthly relative humidity function associated with sea salt
FTP File Transfer Protocol
g Gram
GA Georgia
GB Gigabyte
GEOS Goddard Earth Observing Station
GHRSST Group for High Resolution Sea Surface Temperatures
GIS Geographic Information System
H+ as pH Free acidity
ha Hectare
Hg Total mercury
HGP Particulate mercury
HNO3 Nitric acid
HYSPLIT Hybrid Single Particle Lagrangian Integrated Trajectory
IC Initial conditions
IMPROVE Interagency Monitoring of Protected Visual Environments
IPXWRF Intermediate Processor for Pleim–Xiu for WRF
IPM Integrated Planning Model
JJA June, July, and August
K+ Potassium ion
km Kilometers
kv Eddy diffusivity
KY Kentucky
L Liter
LAC Light absorbing carbon
LCP Landscape
m Meters
m2 Square meters
m3 Cubic meters
MANE-VU Mid-Atlantic/Northeast Visibility Union
MAM March, April, and May
MAR Marine, aircraft, and rail
mb Millibar
MB Mean Bias
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MDA8 Daily maximum 8-hour average
MDL Method Detection Level
MDN Mercury Deposition Network
ME Mean Error
MFB Mean Fractional Bias
MFE Mean Fractional Error
mg Milligram
Mg2+ Magnesium ion
µg Microgram
MJO Multi-Jurisdictional Organization
MLM Multi-Layer Model
Mm Megameters
Modeled Mean Modeled value
MOVES Motor Vehicles Emissions Simulator
MPE Model performance evaluation
MPI Message Passing Interface
MS Mississippi
Na+ Sodium ion
NAAQS National Ambient Air Quality Standards
NADP National Atmospheric Deposition Program
NAICS North American Industry Classification System
NAM-12 North American Mesoscale forecast data at the 12-km level
NC North Carolina
NCAR National Center for Atmospheric Research
NCDC National Climatic Data Center
NCEI National Centers for Environmental Information
NCEP National Centers for Environmental Prediction
NH3 Ammonia
NH4+ Ammonium ion
NLCD National Land Cover Database
NMB Normalized Mean Bias
NME Normalized Mean Error
NO2 Nitrogen dioxide
NO Nitric oxide
NO3- Nitrate
NOAA National Oceanic and Atmospheric Administration
NODA Notice of data availability
NOx Oxides of nitrogen
O3 Ozone
OC Organic carbon
OCM Organic carbon mass
OM Organic matter
OMI Ozone Monitoring Instrument
ORIS Plant identifier issued by U.S. Department of Energy
PAL Particulate Aluminum
PAMS Photochemical Assessment Monitoring System
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Pb Lead
PBL Planetary Boundary Layer
PCA Particulate Calcium
PEC Primary elemental carbon
PFE Particulate Iron
PGI Portland Group, Inc.
PGMs Photochemical grid models
PiG Plume-in-Grid
PM Particulate matter
PM10-PRI Primary particulate matter less than or equal to 10 microns in aerodynamic
diameter
PM2.5 Fine particle; primary particulate matter less than or equal to 2.5 microns
in aerodynamic diameter
PM2.5-PRI Primary particulate matter less than or equal to 2.5 microns in
aerodynamic diameter
PNH4 Ammonium
PNO3 Particulate nitrate
POA Primary organic carbon
POC Parameter occurrence code
ppb parts per billion
PSAT Particulate Matter Source Apportionment Technology
PSCF Potential Source Contribution Factor
PSI Particulate Silicon
PSO4 Sulfate
PTI Particulate Titanium
Q Emissions
Q/d Emissions over distance
QA Quality Assurance
QC Quality control
r Pearson correlation coefficient
r2 Coefficient of Determination
RH Relative humidity
RHR Regional Haze Rule
RPG Reasonable Progress Goals
RRF Relative response factor
RRTMG Rapid Radiative Transfer Model-Global
SC South Carolina
SCC Source Classification Code
SESARM Southeastern States Air Resource Managers, Inc.
SIP State Implementation Plan
SMARTFIRE Satellite Mapping Automated Reanalysis Tool for Fire Incident
Reconciliation
SMAT-CE Software for Model Attainment Test - Community Edition
SMOKE Sparse Matrix Operator Kernel Emissions
SO2 Sulfur dioxide
SO42- Sulfate
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SOA Secondary organic aerosol
SOAP Secondary organic aerosol partitioning
SON September, October, and November
TDEP Total Deposition
TN Tennessee
TOMS Total Ozone Mapping Spectrometer
TSD Technical Support Document
URP Uniform rate of progress
USDA U.S. Department of Agriculture
USDI U.S. Department of the Interior
VA Virginia
VISTAS Visibility Improvement - State and Tribal Association of the Southeast
VISTAS_12 12-km modeling domain for the VISTAS study area
VMT Vehicle Miles Travelled
VOC Volatile organic compounds
WRF Weather Research Forecast
WV West Virginia
YSU Yonsei University
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1.0 INTRODUCTION
1.1 Overview
Southeastern States Air Resource Managers, Inc. (SESARM) has been designated by the United
States Environmental Protection Agency (EPA) as the entity responsible for coordinating
regional haze evaluations for the ten Southeastern states of Alabama, Florida, Georgia,
Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia.
The Eastern Band of Cherokee Indians and the Knox County, Tennessee local air pollution
control agency are also participating agencies. These parties are collaborating through the
Regional Planning Organization known as Visibility Improvement - State and Tribal Association
of the Southeast (VISTAS) in the technical analyses and planning activities associated with
visibility and related regional air quality issues. VISTAS analyses will support the VISTAS
states in their responsibility to develop, adopt, and implement their State Implementation Plans
(SIPs) for regional haze.
The state and local air pollution control agencies in the Southeast are mandated to protect human
health and the environment from the impacts of air pollutants. They are responsible for air
quality planning and management efforts including the evaluation, development, adoption, and
implementation of strategies controlling and managing all criteria air pollutants including fine
particles and ozone as well as regional haze. This project will focus on regional haze and
regional haze precursor emissions. Control of regional haze precursor emissions will have the
additional benefit of reducing criteria pollutants as well.
The 1999 Regional Haze Rule (RHR) identified 18 Class I Federal areas (national parks greater
than 6,000 acres and wilderness areas greater than 5,000 acres) in the VISTAS region. The 1999
RHR required states to define long-term strategies to improve visibility in Federal Class I
national parks and wilderness areas. States were required to establish baseline visibility
conditions for the period 2000-2004, natural visibility conditions in the absence of anthropogenic
influences, and an expected rate of progress to reduce emissions and incrementally improve
visibility to natural conditions by 2064. The original RHR required states to improve visibility on
the 20% most impaired days and protect visibility on the 20% least impaired days.1 The RHR
requires states to evaluate progress toward visibility improvement goals every five years and
submit revised SIPs every ten years.
EPA finalized revisions to various requirements of the RHR in January 2017 (82 FR 3078) that
were designed to strengthen, streamline, and clarify certain aspects of the agency’s regional haze
program including:
A. Strengthening the Federal Land Manager (FLM) consultation requirements to ensure that
issues and concerns are brought forward early in the planning process.
B. Updating the SIP submittal deadlines for the second planning period from July 31, 2018
to July 31, 2021 to ensure that they align where applicable with other state obligations
under the Clean Air Act. The end date for the second planning period remains 2028; that
1 RHR summary data is available at: http://vista.cira.colostate.edu/Improve/rhr-summary-data/
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is, the focus of state planning will be to establish reasonable progress goals for each Class
I area against which progress will be measured during the second planning period. This
extension will allow states to incorporate planning for other Federal programs while
conducting their regional haze planning. These other programs include: the Mercury and
Air Toxics Standards, the 2010 1-hour sulfur dioxide (SO2) National Ambient Air
Quality Standards (NAAQS); the 2012 annual fine particle (PM2.5) NAAQS; and the
2008 and 2015 ozone NAAQS.
C. Adjusting interim progress report submission deadlines so that second and subsequent
progress reports will be due by: January 31, 2025; July 31, 2033; and every ten years
thereafter. This means that one progress report will be required midway through each
planning period.
D. Removing the requirement for progress reports to take the form of SIP revisions. States
will be required to consult with FLMs and obtain public comment on their progress
reports before submission to the EPA. EPA will be reviewing but not formally approving
or disapproving these progress reports.
The RHR defines “clearest days” as the 20% of monitored days in a calendar year with the
lowest deciview (dv)index values. “Most impaired days” are defined as the 20% of monitored
days in a calendar year with the highest amounts of anthropogenic visibility impairment. The
long-term strategy and the reasonable progress goals must provide for an improvement in
visibility for the most impaired days since the baseline period and ensure no degradation in
visibility for the clearest days since the baseline period.
This document serves as the air quality Modeling Protocol for SESARM’s VISTAS II regional
haze modeling analysis in support of estimating regional haze and progress goals at southeastern
state Class I areas in projection year 2028. The reasonable progress goals must provide for a rate
of improvement sufficient to attain “natural conditions” by 2064, or justify any alternative rate.
States are to define controls to meet progress goals every 10 years, starting in 2018 that defines
progress periods ending in 2018, 2028, 2038, 2048, 2058 and finally 2064. States will determine
whether they are meeting their goals by comparing visibility conditions from one five-year
period to another (e.g., 2000-2004 to 2013- 2017). As stated in 40 CFR 51.308 (d) (1), baseline
visibility conditions, progress goals, and changes in visibility must be expressed in terms of dv
units. The dv unit of visibility impairment is derived from beta light extinction (bext) as follows:
dv = 10 ln (bext/10)
Where bext is expressed in terms of inverse megameters (Mm-1 = (106 m)-1).
This Modeling Protocol describes the overall modeling activities to be performed in order to
estimate regional haze and progress at southeastern state Class I areas in projection year 2028.
This effort is being undertaken working closely with SESARM and other state, local, and tribal
agencies.
A comprehensive Modeling Protocol for regional haze study consists of many elements. Its main
function is to serve as a means for planning and communicating how a modeled analysis will be
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performed before it occurs. The protocol guides the technical details of a modeling study and
provides a formal framework within which the scientific assumptions, operational details,
commitments and expectations of the various participants can be set forth explicitly and means
for resolution of potential differences of technical and policy opinion can be worked out openly
and within prescribed time and budget constraints.
As noted in the EPA regional haze modeling guidance, the Modeling Protocol serves several
important functions (EPA, 2007; 2014e):
• Identify the assistance available to SESARM (the lead agencies) to undertake and
evaluate the analysis needed to support the analysis;
• Identify how communication will occur among State, Local, and Federal agencies and
stakeholders to develop a consensus on various issues;
• Describe the review process applied to key steps in the analysis; and
• Describe how changes in methods and procedures or in the protocol itself will be agreed
upon and communicated with stakeholders and the appropriate EPA Regional Office.
Update and Addendum to the June 2018 Modeling Protocol
As the modeling study has evolved since approval of this modeling protocol, certain technical
aspects have been updated to account for changes in emissions inventories, modeling software
and procedures, and quality assurance procedures. These updates have been incorporated into
this version of the Modeling Protocol.
1.2 Study Background
In Section 169A of the Clean Air Act, Congress established a visibility protection goal to prevent
future and remedy existing impairment of visibility resulting from manmade pollution in certain
national parks and wilderness areas. The statute was codified at 42 U.S. Code §7491. EPA issued
regulations implementing the visibility protection mandate that may be found at 40 CFR 51.300
through 51.309. These regulations have been amended several times, most recently as published
in the Federal Register on January 10, 2017.
The 1999 RHR (64 FR 35714) identified 156 parks and natural areas as “mandatory Class I
Federal areas” for which goals would be established to improve visibility to natural conditions.
The 18 Class I areas located in the VISTAS region are tabulated in Table 1-1 that follows. Each
row contains the official Class I area name, the state(s) in which it is located, estimated total land
area in acres based on current available information, and the designated Federal Land Manager
(FLM). A map of the VISTAS Class I areas follows in Figure 1-1.
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Table 1-1. VISTAS Region Federal Class I Area List
(State) Class I Area Name Approx. Acreage Federal Land Manager
AL – Sipsey Wilderness Area 12,726 USDA Forest Service
FL – Chassahowitzka Wilderness Area 23,579 USDI Fish and Wildlife Service
FL – Everglades National Park 1,399,078 USDI National Park Service
FL – Saint Marks Wilderness Area 17,350 USDI Fish and Wildlife Service
GA/TN – Cohutta Wilderness Area GA – 35,268
TN – 1,709
USDA Forest Service
GA – Okefenokee Wilderness Area 353,981 USDI Fish and Wildlife Service
GA – Wolf Island Wilderness 5,126 USDI Fish and Wildlife Service
KY – Mammoth Cave National Park 52,830 USDI National Park Service
NC/TN – Great Smoky Mountains
National Park
NC – 277,432
TN – 244,645
USDI National Park Service
NC/TN – Joyce Kilmer-Slickrock
Wilderness
NC – 13,590
TN – 3,820
USDA Forest Service
NC – Linville Gorge Wilderness Area 11,651 USDA Forest Service
NC – Shining Rock Wilderness Area 18,479 USDA Forest Service
NC – Swanquarter Wilderness Area 8,800 USDI Fish and Wildlife Service
SC – Cape Romain Wilderness 29,000 USDI Fish and Wildlife Service
VA – James River Face Wilderness 8,907 USDA Forest Service
VA – Shenandoah National Park 199,173 USDI National Park Service
WV – Dolly Sods Wilderness 17,776 USDA Forest Service
WV – Otter Creek Wilderness 20,706 USDA Forest Service
USDA – United States Department of Agriculture. USDI – United States Department of Interior.
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'
Figure 1-1. VISTAS Region Class I Areas.
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The 1999 RHR required states to define long-term strategies to improve visibility in Federal
Class I national parks and wilderness areas. States were required to establish baseline visibility
conditions for the period 2000-2004, natural visibility conditions in the absence of anthropogenic
influences, and an expected rate of progress to reduce emissions and improve visibility
systematically to reach natural visibility conditions by 2064. The original RHR required states to
improve visibility on the 20% most impaired days and protect visibility on the 20% clearest days.
States were required to submit SIPs by December 17, 2007 demonstrating reasonable progress to
achieve incremental visibility improvements for the 2008-2018 planning period.
The RHR requires states to evaluate progress toward visibility improvement goals every five
years and submit revised SIPs every ten years. States are to consult with FLMs in developing the
SIPs.
1.2.1 Natural and Current Base Model Period DV Values at the VISTAS Class I Areas
Table 1-2 shows the U.S. EPA calculated natural conditions on the 20% most impaired days and
dv values on the 20% clearest and most impaired days at each VISTAS Class I area for the base
model period (2009-2013).
Table 1-2. Natural Conditions and Base Year Deciview (dv) Values on the 20% Clearest
and 20% Most Impaired Days at each VISTAS Class I Area for the Base Model Period
(2009-2013)2
Class I
Area
Site ID Class I Area Name
IMPROVE
Site ID
Natural Conditions
20% Most Impaired
Days (dv)
Base Year
(2009-2013)
20%
Clearest
Days (dv)
Base Year
(2009-2013)
20% Most
Impaired
Days (dv)
CHAS Chassahowitzka CHAS1 8.97 13.76 19.94
COHU Cohutta Wilderness COHU1 9.52 10.94 21.19
DOSO Dolly Sods
Wilderness
DOSO1 8.92 9.03 21.59
EVER Everglades NP EVER1 8.34 11.23 16.30
GRSM Great Smoky
Mountains NP
GRSM1 10.05 10.63 21.39
JARI James River Face
Wilderness
JARI1 9.48 11.79 21.37
JOYC Joyce-Kilmer-
Slickrock
Wilderness
GRSM1 10.05 10.63 21.39
LIGO Linville Gorge
Wilderness
LIGO1 9.70 9.70 20.39
MACA Mammoth Cave NP MACA1 9.79 13.69 24.04
OKEF Okefenokee OKEF1 9.47 13.34 20.70
OTCR Otter Creek
Wilderness
DOSO1 8.92 9.03 21.59
ROMA Cape Romain ROMA1 9.79 13.59 21.48
2 Tables 3-2 and 3-3, EPA, 2017b.
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Table 1-2. Natural Conditions and Base Year Deciview (dv) Values on the 20% Clearest
and 20% Most Impaired Days at each VISTAS Class I Area for the Base Model Period
(2009-2013)2
Class I
Area
Site ID Class I Area Name
IMPROVE
Site ID
Natural Conditions
20% Most Impaired
Days (dv)
Base Year
(2009-2013)
20%
Clearest
Days (dv)
Base Year
(2009-2013)
20% Most
Impaired
Days (dv)
SAMA St. Marks SAMA1 9.19 13.33 20.11
SHEN Shenandoah NP SHEN1 9.52 8.60 20.72
SHRO Shining Rock
Wilderness*
SHRO1 9.70 5.36 19.05
SIPS Sipsey Wilderness SIPS1 9.55 12.84 21.67
SWAN Swanquarter SWAN1 9.79 11.76 19.76
WOLF Wolf Island OKEF1 9.47 13.34 20.70
* The IMPROVE monitor at Shinning Rock Wilderness Area is missing complete data for 2010 and 2011. After consultation
with North Carolina, a 3-year average of 2009, 2012, and 2013 IMPROVE data was used to calculate the visibility (dv) for
both the 20% clearest and 20% most impaired days at Shinning Rock.
1.2.2 Purpose
This document serves as the first draft of the Air Quality Modeling Protocol plan for the
VISTAS II Regional Haze modeling analysis to be performed by the contractor team Eastern
Research Group, Inc. (ERG) and Alpine Geophysics, LLC (Alpine) with the purpose of
estimating regional haze and progress at southeastern state Class I areas in projection year 2028.
It is presumed that this information will be used by SESARM-participating states in the regional
haze SIP development process.
1.3 Lead Agency and Principal Participants
SESARM is the lead agency in the development of this regional haze modeling analysis. EPA
Region 4 in Atlanta, GA is the EPA Regional Office that will take the lead in the review and
approval process for this project.
1.4 Related Regional Modeling Studies
There are other regional haze modeling studies related to the VISTAS II regional haze modeling
analysis whose results may be useful to SESARM.
1.4.1 EPA Preliminary 2028 Regional Haze Modeling
EPA recently conducted preliminary visibility modeling (EPA, 2017b) for year 2028 with the
intention of informing the regional haze SIP development process. For their assessment, air
quality modeling was used to project visibility levels at individual Class I areas (represented by
Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring sites) to
2028 and to estimate emissions sector contributions to 2028 particulate matter (PM)
concentrations and visibility. The projected 2028 PM concentrations were converted to light
extinction coefficients and then to dvs; these values are used to evaluate visibility progress as of
Final Modeling Protocol
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2028. In addition, 2028 visibility contribution information by major emissions source sector was
calculated using particulate source apportionment technology (PSAT).
EPA found that visibility at most eastern Class I areas on the 20% most anthropogenically
impaired days is projected to be below the unadjusted glidepath in 2028, with a relatively higher
percentage of the light extinction due to domestic anthropogenic sources.
Based on their assessment of these results, EPA also identified a number of uncertainties and
model performance issues that should be addressed in future EPA, state, multistate, or
stakeholder modeling that may be used in SIP development. They have identified several aspects
of this initial modeling that should be improved upon through coordination with interested
stakeholders. These include, but are not limited to:
• Expanded domain size to reduce the impact of the boundary conditions assumptions on
predictions, especially near the domain edge.
o The boundary conditions were found to be the largest contributor to visibility at
many Class I areas, especially those near the edge of the modeling domain.
Expanding the regional photochemical modeling domain will potentially reduce
the influence from global or hemispheric model derived boundary conditions.
Those models have much coarser grid resolution and use global emissions
inventories which may not be year specific or up to date.
o There may also be recirculation of U.S. emissions in boundary conditions derived
from global models, especially where the boundary is very close to the U.S.
mainland. Moving the domain boundary further from the contiguous U.S. will
minimize this issue.
• Updated emission inventory and projections for certain sectors.
o More recent nationwide photochemical modeling has incorporated updates in
future year emissions inventories that should be considered for 2028.
Remove the Clean Power Plan and Texas regional haze FIP from the
electric generating unit (EGU) assumptions.
Updates to the oil and gas emissions projections.
New Canadian base and future year emissions.
Other emissions updates based on more recent information, such as state
review of facilities of interest within the VISTAS domain.
• Updated boundary conditions based on more recent modeling of international emissions
as well as additional modeling to help quantify and distinguish anthropogenic and natural
international contributions.
o The 2011 boundary conditions used for the regional haze modeling came from an
older version of Goddard Earth Observing System (GEOS)-Chem which did not
contain the latest international emissions estimates for 2011.
o In addition to projecting U.S. emissions to 2028, international emissions are
changing between 2011 and 2028 as well. Consideration should be given to
estimating future year global emissions to provide an alternate estimate of future
year boundary conditions.
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o Global or hemispheric models can potentially be used to adjust the visibility
glidepath for impacts from international anthropogenic sources. Sensitivity runs
and additional refinements to international inventories may be needed in order to
provide more confidence in the model results.
• Improved treatment of fire and fugitive dust emissions in the model.
o The current Comprehensive air quality model with extensions (CAMx) modeling
platform does not include estimates of natural windblown dust emissions.
Windblown dust (primarily contributing to coarse mass) is an important
component of regional haze in some Class I areas.
o The current modeling used year-specific fire emissions from 2011 which may not
be representative of a “typical year” or multi-year period. The IMPROVE
measurements used to establish both the base period impairment measurements
and progress towards natural conditions, use a five-year average of IMPROVE
measurements. Therefore, alternative estimates of fire emissions, which may
better represent a longer term average, may be more appropriate for use in
visibility projections.
o Further refinements of fire emissions may also allow exploration of possible
adjustments of the glidepath for prescribed fire impacts.
• Treatment of secondary organic aerosols (SOA) should be reviewed.
o In many locations, there is relatively high modeled SOA as a fraction of total
organic aerosols. Using the RRF approach, this apportions the modeled SOA as a
fraction of the measured total organics. There is considerable uncertainty in the
modeled SOA concentrations, which therefore translates into uncertainty in the
apportioned SOA mass.
o Additional information can be gained by running PSAT with SOA source
apportionment turned on.
• Estimation of “natural visibility conditions” used in the glidepath framework should be
further reviewed.
o Further refinements in the draft methodology can be explored.
o Further analysis of the IMPROVE data combined with modeled source
apportionment information may be useful in evaluating the natural conditions
estimates.
All of these options were considered for this project; however due to schedule and resource
constraints SESARM chose only to move forward with correcting the emission projections.
1.4.2 Maine Department of Environmental Protection Tracking Visibility Progress 2004-
2016
This document (ME DEP, 2018), prepared by the Maine Department of Environmental
Protection for the Mid-Atlantic/Northeast Visibility Union (MANE-VU), presents visibility
trends at IMPROVE monitoring sites at federal Class I areas in and adjacent to the MANE-VU
region that are subject to the USEPA’s RHR. This document also presents visibility trends at
IMPROVE Protocol monitoring sites in and adjacent to the MANE-VU region. The analyses
Final Modeling Protocol
August 2020 10
were performed to determine the extent of progress in meeting short-term and long-term
visibility goals for the first RHR SIP period that ends in 2018 using metrics specified in the state
SIPs.
The technical document provides an analysis of visibility data collected at the IMPROVE
monitoring sites, starting in the baseline period of 2000-2004 through 2012-2016, the most
recent five-year period with available data.
The results of the analysis continue to show the following:
• There continue to be definite downward trends in overall haze level at all Class I areas in
and adjacent to the MANE-VU region and at IMPROVE Protocol monitoring sites.
• Based on rolling five-year averages demonstrating progress since the 2000-2004 baseline
period, the MANE-VU Class I areas are on track to meet their 2018 Reasonable Progress
Goals (RPGs) for both 20% clearest and 20% most impaired visibility days.
• The trends are mainly driven by large reductions in sulfate light extinction, and to a lesser
extent, nitrate light extinction.
• Levels of organic carbon mass (OCM) and light absorbing carbon (LAC) appear to be
approaching natural background levels at most of the MANE-VU Class I areas.
• In all cases, the levels set by 2018 RPG’s have already been met, and progress beyond
these goals appears achievable.
• The percent contribution of nitrate light extinction has been significantly increasing at
most of the MANE-VU Class I areas.
1.5 Overview of Modeling Approach
The VISTAS II modeling proposed here will include particulate matter simulations and source
apportionment studies using the 12 kilometer (km) grid based on EPA’s 2011/2028el modeling
platform and preliminary source contribution assessment (EPA, 2017b) updated to include a
12km subdomain over the VISTAS region and augmented with revisions to EGU and non-EGU
point source projections.
1.5.1 Episode Selection
Episode selection is an important component of any modeling analysis. EPA guidance
recommends that one choose time periods which reflect the variety of meteorological conditions
which represent visibility impairment on the 20% clearest and 20% most impaired days in the
Class I areas being modeled (high and low concentrations necessary). This is best accomplished
by modeling a full year. For this analysis, Alpine will be modeling the full 2011 calendar year
with 10 days of model spin-up in 2010.
1.5.2 Model Selection
Details on the rationale for model selection are provided in Section 2. The Weather Research
Forecast (WRF) prognostic meteorological model was selected for the VISTAS II modeling.
Emissions processing will be completed using the Sparse Matrix Operator Kernel Emissions
(SMOKE) model for most source categories. The exceptions are that Biogenic Emissions
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August 2020 11
Inventory System (BEIS) model was used for biogenic emissions and there are special
processors for fires, windblown dust, lightning and sea salt emissions. The 2014 Motor Vehicle
Emissions Simulator (MOVES) onroad mobile source emissions model was used by EPA with
SMOKE-MOVES to generate onroad mobile source emissions with EPA generated vehicle
activity data provided in the 2028 regional haze analysis. The CAMx photochemical grid model,
which supports two-way grid nesting will also be used. The setup is based on the same
WRF/SMOKE/BEIS/CAMx modeling system used in the EPA 2011/2028el platform modeling.
During the preparation of this Modeling Protocol, it was noted that a newer version of CAMx,
Version 6.50, was released (April 30, 2018). After discussions with SESARM, the CC, and the
TAWG, it was decided to not use the newer version due to insufficient testing and application
history necessary for to ensure confidence in modelling results.
1.5.3 Base and Future Year Emissions Data
A 2011 base year and 2028 future year will be used for the VISTAS II modeling to be consistent
with the requirements of EPA’s RHR. The 2011 base case and 2028 future year emissions will
be founded on EPA’s “el” modeling platform with no adjustments made to 2011 estimates.
Updates will be made to EGU and non-EGU point source data within the VISTAS domain for
2028, as documented in the Task 2B report for SESARM states and Task 3B report for the non-
SESARM states. One such example is the replacement of the Eastern Regional Technical
Advisory Committee (ERTAC) EGU v.2.7 outputs with the more recent 16.0 and 16.1 outputs
based on state direction. Additionally, some states chose to not replace their EGU emissions
from the original modeling.
1.5.4 Emission Input Preparation and QA/QC
Quality assurance (QA) and quality control (QC) of the emissions datasets are critical steps in
performing air quality modeling studies. Because emissions processing is tedious, time
consuming and involves complex manipulation of many different types of large databases,
rigorous QA measures are a necessity to prevent errors in emissions processing from occurring.
The VISTAS II modeling study will utilize methods applied to the emissions platform that
follows a multistep emissions QA/QC approach. Additional QA/QC involves more robust
scrutinization of products from the multiple Benchmark Comparisons, as listed in Section 6.5.2
of this document.
1.5.5 Meteorology Input Preparation and QA/QC
The CAMx 2011 12 km meteorological inputs will be based on WRF meteorological modeling
conducted by EPA. Details on the EPA 2011 WRF application and evaluation are provided by
EPA (EPA 2014d).
1.5.6 Initial and Boundary Conditions Development
Initial concentrations (IC) and Boundary Conditions (BCs) are important inputs to the CAMx
model. Alpine intends to run 10 days of model spin-up before the first days occur in the
modeling episode so the ICs are washed out of the modeling domain before the first day of the
annual 2011 modeling period. The lateral boundary and initial species concentrations are
provided by a three-dimensional global atmospheric chemistry model, GEOS-Chem (Yantosca,
2004) standard version 8-03-02 with 8-02-01 chemistry.
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1.5.7 Air Quality Modeling Input Preparation and QA/QC
Each step of the air quality modeling will be subjected to QA/QC procedures. These procedures
will include verification of model configurations, confirmation that the correct data were used
and were processed correctly and other procedures.
1.5.8 Model Performance Evaluation
An operational model performance evaluation will be performed for particulate matter (PM2.5
species components and coarse PM) and regional haze to examine the ability of the CAMx v6.40
modeling system to simulate 2011 measured concentrations. This evaluation will focus on
graphical analyses and statistical metrics of model predictions versus observations.
1.5.9 Diagnostic Sensitivity Analyses
Depending on the confirmation run results of the CAMx 2011 base case modeling and MPE on
Alpine’s modeling system, diagnostic sensitivity tests may be conducted to try and improve
model performance. The definition of these diagnostic sensitivity tests will depend on the results
of the initial MPE for these domains.
1.5.10 Future Year Significant Contribution Modeling
PM predictions from 2011 and 2028 CAMx model simulations will be used to project 2009-2013
IMPROVE visibility data to 2028 following the approach described in EPA’s ozone, PM2.5 and
regional haze modeling guidance (US EPA, 2014b). The guidance describes the recommended
modeling analysis used to help set RPGs that reflect emissions controls in a regional haze SIP.
The CAMx PSAT method will be utilized for this effort.
1.6 Project Participants and Contacts
SESARM is the lead agency in the development of the VISTAS II modeling analysis. They will
work closely with other local agencies, other local cities and agencies, and EPA Region 4 in the
study, including the sharing of interim results as they become available. SESARM will also work
with local, state, and tribal agencies and stakeholders in the modeling analysis, where
stakeholders may include environmental groups and industry. Key participants in the VISTAS II
study and their contact information are provided in Table 1-3.
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Table 1-3. Key Participants and Contact Information for the VISTAS II Modeling Study
Organization
Individual(s)
[Role] Address Contact Numbers
Southeastern States Air Resource Managers, Inc. (SESARM)
Metro 4/
SESARM
Mr. John Hornback
SESARM Executive
Director
Southeastern States Air
Resource Managers, Inc.
205 Corporate Center Drive,
Suite D
Stockbridge, GA 30281-7383
(404) 361-4000
hornback@metro4-
sesarm.org
EPA Region 4
EPA Region 4 Mr. Rick Gillam
Environmental
Engineer
EPA Region 4
Sam Nunn Atlanta Federal
Center
61 Forsyth St., SW
Atlanta, GA 30303
(404) 562-9049
gillam.rick@epa.gov
Contractors (Modeling team)
Eastern
Research
Group, Inc.
Mr. Regi Oommen
ERG Program
Manager
Eastern Research Group, Inc.
1600 Perimeter Park Drive,
Suite 200
Morrisville, NC 27560
(919) 468.7829
regi.oommen@erg.com
Alpine
Geophysics,
LLC
Mr. Gregory Stella
Alpine Subcontract
Manager
Senior Scientist
387 Pollard Mine Road
Burnsville, NC 28714
(828) 675-9045
gms@alpinegeophysics.com
Alpine
Geophysics,
LLC
Mr. Dennis
McNally
Alpine Senior
Scientist
Senior Scientist
7341 Poppy Way
Arvada, CO 80007
(303) 421- 2211
dem@alpinegeophysics.com
1.7 Communication
Frequent communication between SESARM and the Modeling team and other participants is
anticipated. These communications will include e-mails, conference calls, and face-to-face
meetings. SESARM envisions that EPA and others will review interim products as they become
available so that comments can be received during the study to allow for corrective action as
necessary. These interim deliverables would include, but not be limited to, preliminary CAMx
model performance evaluation, preliminary current and future-year emissions assumptions and
results, and preliminary future year visibility projections and source apportionment results.
1.8 Schedule
Table 1-4 lists the current schedule for the initial key deliverables under the VISTAS II modeling
study.
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August 2020 14
Table 1-4. Initial Key Deliverables and Dates for the VISTAS II Modeling Through the 2028
Source Apportionment Reporting
Task Subtask Deliverable
Initial Due
Date
Updated
Due Date
2.1 2011 Base year emissions inventories 6/30/2018a No change
2.2a Projection Year Emissions Inventory Comparisons, draft 5/18/2018 1/10/2020
2.2b Projection Year Emissions Inventories, final 6/30/2018a 1/22/2020
2.3a1 2028 EGU Point Source Emissions, draft 5/18/2018 3/15/2020
2.3a2 2028 EGU Point Source Emissions, final 6/30/2018a 3/31/2020
2 2.3b1 2028 Non-EGU Point Source Emissions, draft 5/18/2018 3/15/2020
2.3b2 2028 Non-EGU Point Source Emissions, final 6/30/2018a 3/31/2020
2.3c1 2028 Emissions for Other Categories, draft 5/18/2018 No change
2.3c2 2028 Emissions for Other Categories, final 6/30/2018a No change
2.3d1 Emission Comparisons from 2028v6.3el and 2023v6.3en, draft 5/18/2018 No change
2.3d2 Emission Comparisons from 2028v6.3el and 2023v6.3en, final 6/30/2018a No change
2.3e1 2028 Documentation, draft 5/18/2018 5/22/2020
2.3e2 2028 Documentation, final 6/30/2018a 9/1/2020
2.4 Emissions summaries and Quality Assurance 6/30/2018a 3/31/2020
3.1 Create Photochemical Model-Ready EGU emissions files for 2028 7/13/2018a 4/6/2020
3.1.2 Scale Hourly EGU SMOKE emissions to match annual 2028 7/13/2018a 4/6/2020
3 3.2 Create Photochemical Model-Ready Non-EGU emissions files for 2028 7/13/2018a 4/6/2020
3.3a Merge EGU/non-EGU data from Subtasks 3.1 and 3.2 for CAMx
Model
7/13/2018a 4/13/2020
3.3b* Merge area/MAR data from Subtasks 3.1 and 3.2 for CAMx Model 7/13/2018a No change
4 4 Data acquisition and preparation 6/1/2018 No change
4.1 Acid deposition in watersheds 6/1/2018 No change
5 5 Area of Influence Analysis 9/1/2018 6/20/2019
5.1 SO2 and NOx emissions contribution rankings No later than
9/1/2018
6/20/2019
6 6.1a Modeling protocol, draft 5/2/2018 8/10/2020
6.1b Modeling protocol, final 6/30/2018a 9/15/2020
6.2 2011 base year air quality modeling 9/1/2018 No change
6.3 2028 projection year air quality modeling 12/1/2018 6/29/2020
7 7 Source apportionment tagging - 250 tags (final number to be
determined)
4/19/2019a 6/4/2020
8 8 Model performance evaluation 10/1/2018 12/1/2019
8.1 Model performance evaluation (related to Subtask 4.1) 10/1/2018 12/1/2019
9 9a Future-year model projections 4/19/2019 7/15/2020
9.1 Calculate Relative Response Factors (related to Subtask 4.1) 5/3/2019 9/1/2020
10 10 Website/FTP Site Development; Data Transfer and Archival Ongoing 9/30/2020
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Table 1-4. Initial Key Deliverables and Dates for the VISTAS II Modeling Through the 2028
Source Apportionment Reporting
Task Subtask Deliverable
Initial Due
Date
Updated
Due Date
11 11.1a Extraction of state-specific modeling initial conditions/boundary
conditions (5 states)
Within 1 week
after
completion of
Task 6.2 and
6.3 activities
No change
11.1b* Additional extraction of state-specific modeling initial
conditions/boundary conditions (5 states)
Within 1 week
after
completion of
Task 6.2 and
6.3 activities
No change
11.2a Extraction of state-specific meteorological files (5 states) Within 1 week
after regions
are defined by
the time the
meteorological
data is
windowed for
the
VISTAS_12
domain
No change
11.2b* Additional extraction of state-specific meteorological files (5 states) Within 1 week
after regions
are defined by
the time the
meteorological
data is
windowed for
the
VISTAS_12
domain
No change
a Revised dates based on Amendment 1, dated 5/31/2018
* Optional Task, no decision yet whether to perform it.
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2.0 MODEL SELECTION
This section introduces the models to be used in the VISTAS II regional haze modeling study.
The selection methodology presented in this chapter mirrors EPA’s preliminary 2028 regional
haze modeling (EPA, 2017b).
40 CFR Part 51 Appendix W does not identify a “preferred model” for use in reasonable
progress assessments for regional haze and therefore, EPA does not recommend a specific model
for use in these analyses. The latest EPA modeling guidance (EPA, 2014e) explicitly mentions
the Community Multiscale Air Quality Modeling System (CMAQ) and CAMx photochemical
grid models (PGMs) as the most commonly used PGMs that would satisfy EPA’s selection
criteria but notes that this is not an exhaustive list and does not imply that they are “preferred”
over other PGMs that could also be considered and used with appropriate justification. EPA’s
current modeling guidelines lists the following criteria for model selection (EPA, 2014e):
• It should not be proprietary;
• It should have received a scientific peer review;
• It should be appropriate for the specific application on a theoretical basis;
• It should be used with data bases which are available and adequate to support its
application;
• It should be shown to have performed well in past modeling applications;
• It should be applied consistently with an established protocol on methods and procedures;
• It should have a User’s guide and technical description;
• The availability of advanced features (e.g., probing tools or science algorithms) is
desirable; and
• When other criteria are satisfied, resource considerations may be important and are a
legitimate concern.
Alpine and ERG have been directed by SESARM to use EPA’s 2011el-based air quality
modeling platform which includes emissions, meteorology, and other inputs for 2011 as the base
year for the modeling described in their regional haze TSD (EPA, 2017b). EPA has projected the
2011 base year emissions to a 2028 future year base case scenario. This will be the foundation of
the emissions with revisions for this analysis as described elsewhere. The 2011 modeling
platform and projected 2028 emissions will be used to drive the 2011 base year and 2028 base
case air quality model simulations. As noted in EPA’s documentation, the 2011 base year
emissions and methods for projecting these emissions to 2028 are in large part similar to the data
and methods used by EPA in the final Cross-State Air Pollution Rule (CSAPR) Update 3 and the
subsequent notice of data availability (NODA)4 to support ozone transport for the 2015 ozone
NAAQS.
3 https://www.epa.gov/airmarkets/final-cross-state-air-pollution-rule-update
4 https://www.epa.gov/airmarkets/notice-data-availability-preliminary-interstate-ozone-transport-modeling-data-2015-ozone
Final Modeling Protocol
August 2020 17
The 2011 and 2028 emissions used for EPA’s regional haze modeling are described in the
documents:
• “Preparation of Emissions Inventories for the Version 6.3, 2011 Emissions Modeling
Platform”;5
• “Technical Support Document (TSD) Updates to Emissions Inventories for the Version
6.3 2011 Emissions Modeling Platform for the Year 2028”;6 and
• “EPA Base Case v.5.16 for 2023 Ozone Transport NODA Using IPM Incremental
Documentation.”7
The meteorological data and initial and boundary concentrations used for this regional haze
assessment, as described below, are the same as those used for the Final CSAPR Update air
quality modeling and the 2015 ozone transport NAAQS NODA.
For the VISTAS II regional haze modeling analysis, Alpine and ERG propose to use the
WRF/SMOKE/MOVES2014/BEIS/CAMx-PSAT modeling system as the primary tool for
modeling PM concentrations and visibility and in the calculation of significant contribution to
downwind Class I areas. The proposed modeling system satisfies all of EPA’s selection criteria.
The key models to be used in this regional haze modelling effort are described below:
• WRF/ARW: The Weather Research and Forecasting (WRF)8 Model is a mesoscale
numerical weather prediction system designed to serve both operational forecasting and
atmospheric research needs (Skamarock, 2004; 2006; Skamarock et al., 2005). The
Advanced Research WRF (ARW) version of WRF will be used in this regional haze
analysis study. It features multiple dynamical cores, a 3-dimensional variational
(3DVAR) data assimilation system, and a software architecture allowing for
computational parallelism and system extensibility. WRF is suitable for a broad spectrum
of applications across scales ranging from meters to thousands of kilometers. The effort
to develop WRF has been a collaborative partnership, principally among the National
Center for Atmospheric Research (NCAR), the National Oceanic and Atmospheric
Administration (NOAA), the National Centers for Environmental Prediction (NCEP) and
the Forecast Systems Laboratory (FSL), the Air Force Weather Agency (AFWA), the
Naval Research Laboratory, the University of Oklahoma, and the Federal Aviation
Administration (FAA). WRF allows researchers the ability to conduct simulations
reflecting either real data or idealized configurations. WRF provides operational
forecasting a model that is flexible and efficient computationally, while offering the
advances in physics, numerics, and data assimilation contributed by the research
community.
• MOVES2014: MOVES2014 9 is EPA’s latest onroad mobile source emissions model that
was first released in July 2014 (EPA, 2014a; 2014b; 2014c). MOVES2014 includes the
5 https://www.epa.gov/air-emissions-modeling/2011-version-63-technical-support-document
6 https://www.epa.gov/air-emissions-modeling/2011-version-63-platform
7 https://www.epa.gov/airmarkets/epa-base-case-v516-2015-ozone-naaqs-transport-noda-using-ipm-incremental-
documentation
8 http://www.wrf-model.org/index.php
9 http://www.epa.gov/otaq/models/moves/
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August 2020 18
latest onroad mobile source emissions factor information. Emission factors developed by
EPA will be used in this analysis.
• SMOKE: The SMOKE 10 modeling system is an emissions modeling system that
generates hourly gridded speciated emission inputs of mobile, nonroad, nonpoint area,
point, fire and biogenic emission sources for photochemical grid models (Coats, 1995;
Houyoux and Vukovich, 1999). As with most ‘emissions models’, SMOKE is principally
an emission processing system and not a true emissions modeling system in which
emissions estimates are simulated from ‘first principles’. This means that, with the
exception of mobile and biogenic sources, its purpose is to provide an efficient, modern
tool for converting an existing base emissions inventory data into the hourly gridded
speciated formatted emission files required by a photochemical grid model. SMOKE will
be used to prepare emission inputs for nonroad mobile, nonpoint area, and point sources.
• SMOKE-MOVES 11: SMOKE-MOVES uses an Emissions Factor (EF) Look-Up Table
from MOVES, county-level gridded vehicle miles travelled (VMT) and other activity
data, and hourly gridded meteorological data (typically from WRF) to generate hourly
gridded speciated onroad mobile source emissions inputs.
• ERTAC EGU Forecasting Tool: The ERTAC EGU Forecasting Tool 12 was developed
through a collaborative effort to improve emission inventories among the Northeastern,
Mid-Atlantic, Southeastern, and Lake Michigan area states; other member states; industry
representatives; and multi-jurisdictional organization (MJO) representatives. The tool can
be used to grow base year hourly EGU emissions inventories into future projection years.
The tool uses base year hourly EPA Clean Air Markets Division (CAMD) data, fuel
specific growth rates, and other information to estimate future emissions.
• BEIS: Biogenic emissions were modeled by EPA using version 3.61 of BEIS. First
developed in 1988, BEIS estimates volatile organic compound (VOC) emissions from
vegetation and nitric oxide (NO) emissions from soils. Because of resource limitations,
recent BEIS development has been restricted to versions that are built within the SMOKE
system.
• CAMx: The CAMx 13 model is a state-of-science “One-Atmosphere” photochemical grid
model capable of addressing ozone, PM, visibility, and acid deposition at a regional scale
for periods up to one year (Ramboll Environ, 2016). CAMx is a publicly-available open-
source computer modeling system for the integrated assessment of gaseous and
particulate air pollution. Built on today’s understanding that air quality issues are
complex, interrelated, and reach beyond the urban scale, CAMx is designed to:
(a) simulate air quality over many geographic scales; (b) treat a wide variety of inert and
chemically active pollutants including ozone, inorganic and organic PM2.5 and PM10 and
mercury and toxics; (c) provide source-receptor, sensitivity, and process analyses; and
(d) be computationally efficient and easy to use. The U.S. EPA has approved the use of
CAMx for numerous ozone, PM, and regional haze SIPs throughout the U.S. and has
used this model to evaluate regional mitigation strategies including those for most recent
10 http://www.smoke-model.org/index.cfm
11 https://www.epa.gov/sites/production/files/2016-06/documents/smoke-moves-2011.pdf
12 http://www.marama.org/2013-ertac-egu-forecasting-tool-documentation
13 http://www.camx.com
Final Modeling Protocol
August 2020 19
regional-scale rules (e.g., Transport Rule, Clean Air Interstate Rule (CAIR), NOX SIP
Call, etc.). CAMx Version 6.40 will be used in this study, with the secondary organic
aerosol partitioning (SOAP) algorithm module as the default.
• During the preparation of this Modeling Protocol, it was noted that a newer version of
CAMx, Version 6.50, was released (April 30, 2018). After discussions with SESARM,
the CC, and the TAWG, it was decided to not use the newer version due to insufficient
testing and practical usage necessary for to ensure confidence in potential modelling
results.
• PSAT: The PSAT tool of CAMx was selected to develop source contribution and
significant contribution calculations.
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August 2020 20
3.0 EPISODE SELECTION
EPA’s most recent regional haze modeling guidance (EPA, 2014e) contains recommended
procedures for selecting modeling episodes. The VISTAS II regional haze modeling will use the
annual calendar year 2011 modeling period because it satisfies the most criteria in EPA’s
modeling guidance episode selection discussion and is consistent with the base year modeling
platform. Specifically, EPA’s guidance recommends choosing a time period which reflects the
variety of meteorological conditions that represent visibility impairment on the 20% clearest and
20% most-impaired days in the Class I areas being modeled (high and low concentrations
necessary). This is best accomplished by modeling a full calendar year.
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August 2020 21
4.0 MODELING DOMAIN SELECTION
This section summarizes the modeling domain definitions for the VISTAS II regional haze
modeling, including the domain coverage, resolution, and map projection. It also discusses
emissions, aerometric, and other data available for use in model input preparation and
performance testing.
4.1 Horizontal Domains
The VISTAS II modeling will use a 12 km continental U.S. (CONUS_12 or 12US2) domain.
The 12 km nested grid modeling domain configuration is shown in Figure 4-1. The 12 km
domain shown in Figure 4-1 represents the CAMx 12km air quality and SMOKE/BEIS
emissions modeling domain. The WRF meteorological modeling was run on larger 12 km
modeling domains than used for CAMx as demonstrated in EPA’s meteorological model
performance evaluation document (EPA, 2014d). The WRF meteorological modeling domains
are defined larger than the air quality modeling domains because meteorological models can
sometimes produce artifacts in the meteorological variables near the boundaries as the prescribed
boundary conditions come into dynamic balance with the coupled equations and numerical
methods in the meteorological model.
An additional VISTAS_12 domain will be prepared that is a subset of the CONUS_12 domain,
with dimensions for both provided in Table 4-1. Development of the VISTAS_12 domain (also
presented in Figure 4-1) will require the EPA CONUS_12 simulation to be run using CAMx
Version 6.40 modeling saving 3-dimensional concentration fields for extraction using the CAMx
BNDEXTR program.
Figure 4-1. Map of 12km CAMx Modeling Domains. VISTAS_12 Domain Represented as
Inner Red Domain.
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Table 4-1. VISTAS II Modeling Domain Specifications
Domain Columns Rows Vertical Layers X Origin (km) Y Origin (km)
CONUS_12 396 246 25 -2,412 -1,620
VISTAS_12 269 242 25 -912 -1,596
4.2 Vertical Modeling Domain
The CAMx vertical structure is primarily defined by the vertical layers used in the WRF
meteorological modeling. The WRF model employs a terrain following coordinate system
defined by pressure, using multiple layer interfaces that extend from the surface to 50 mb
(approximately 19 km above sea level). EPA ran WRF using 35 vertical layers. A layer
averaging scheme is adopted for CAMx simulations whereby multiple WRF layers are combined
into one CAMx layer to reduce the air quality model computational time. Table 4-2 displays the
approach for collapsing the WRF 35 vertical layers to 25 vertical layers in CAMx and is
consistent with EPA’s draft 2028 regional haze modeling.14
Table 4-2. WRF and CAMx Layers and Their
Approximate Height Above Ground Level
CAMx
Layer
WRF
Layers Sigma P
Pressure
(mb)
Approx.
Height
(m AGL)
25 35 0.00 50.00 17,556
34 0.05 97.50 14,780
24 33 0.10 145.00 12,822
32 0.15 192.50 11,282
23 31 0.20 240.00 10,002
30 0.25 287.50 8,901
22 29 0.30 335.00 7,932
28 0.35 382.50 7,064
21 27 0.40 430.00 6,275
26 0.45 477.50 5,553
20 25 0.50 525.00 4,885
24 0.55 572.50 4,264
19 23 0.60 620.00 3,683
18 22 0.65 667.50 3,136
17 21 0.70 715.00 2,619
16 20 0.74 753.00 2,226
15 19 0.77 781.50 1,941
14 18 0.80 810.00 1,665
13 17 0.82 829.00 1,485
12 16 0.84 848.00 1,308
11 15 0.86 867.00 1,134
10 14 0.88 886.00 964
9 13 0.90 905.00 797
12 0.91 914.50 714
8 11 0.92 924.00 632
14 Table 2-2, EPA, 2017b.
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Table 4-2. WRF and CAMx Layers and Their
Approximate Height Above Ground Level
CAMx
Layer
WRF
Layers Sigma P
Pressure
(mb)
Approx.
Height
(m AGL)
10 0.93 933.50 551
7 9 0.94 943.00 470
8 0.95 952.50 390
6 7 0.96 962.00 311
5 6 0.97 971.50 232
4 5 0.98 981.00 154
4 0.99 985.75 115
3 3 0.99 990.50 77
2 2 1.00 995.25 38
1 1 1.00 997.63 19
5.0 DATA AVAILABILITY
The CAMx modeling systems requires emissions, meteorology, surface characteristics, initial
and boundary conditions (IC/BC), and ozone column data for defining the inputs.
5.1 Emissions Data
Without exception, as directed by SESARM, the 2011 base year emissions inventories for this
analysis will be based on emissions obtained from the EPA’s “el” modeling platform. This
platform was prepared by EPA and used in the regional haze modeling for 2028. Emissions for
2028 will be based on a mixture of EPA’s 2028el sectors and updated emissions as prepared by
SESARM for inclusion in this study.
5.2 Ambient Air Quality Observations
Year 2011 data from all available ambient air monitoring networks for gas and PM species are
used in the model performance evaluation. Table 5-1 summarizes routine ambient gaseous and
PM monitoring networks available in the U.S. Alpine will focus on the ambient data collected
from the IMPROVE network. This network began in 1985 as a cooperative visibility monitoring
effort between EPA, federal land management agencies, and state air agencies (IMPROVE,
2011). Data are collected at Class I areas across the United States mostly at National Parks,
National Wilderness Areas, and other protected pristine areas. Currently, there are approximately
181 IMPROVE sites that have complete annual PM2.5 mass and/or PM2.5 species data. There are
110 IMPROVE monitoring sites which represent air quality at the 156 designated Class I areas.
The 71 additional IMPROVE sites are “IMPROVE protocol” sites which are generally located in
rural areas throughout the U.S. Although these sites use the IMPROVE monitoring samplers and
collection routines, they are not located at Class I areas.
5.3 Meteorological Data
The 2011 meteorological data for the air quality modeling of 2011 and 2028 will be derived from
EPA’s run of Version 3.4 of the WRF Model (Skamarock, et al., 2008) as completed for their
regional haze modeling analysis for 2028 (EPA, 2017b).
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5.4 Ozone Column Data
Ozone column data were derived by EPA using the Total Ozone Mapping Spectrometer (TOMS)
with aboard Ozone Monitoring Instrument (OMI) satellite platform 15 for 2011 at a daily,
1 degree resolution. These data will be used as obtained directly from EPA for the 12US2
simulations. EPA developed new ozone column data for their more current 2023en simulation.
This more recent data will be used for the final VISTAS 2011 and 2028 modeling. For the
VISTAS_12 domain simulations, the data will be windowed onto the smaller VISTAS_12
domain.
5.5 Photolysis Rates
Photolysis rates were calculated using the NCAR Tropospheric Ultraviolet and Visible (TUV)
Radiation Model Version 4.8. These data will be used as obtained directly from EPA. The final
VISTAS 2011 and 2028 simulations will use the updated photolysis data EPA developed for the
2023en simulation.
5.6 Land Use
Land use and land cover data is based on the 2006 National Land Cover Database (NLCD2006)
data.16 These data will be used as obtained directly from EPA for the 12US2 simulations. For the
VISTAS_12 domain simulations, the data will be windowed onto the smaller region.
5.7 Initial and Boundary Conditions Data
The lateral boundary and initial species concentrations are provided by a three-dimensional
global atmospheric chemistry model, GEOS-Chem (Yantosca, 2004) standard version 8-03-02
with 8-02-01 chemistry. The global GEOS-Chem model simulates atmospheric chemical and
physical processes driven by assimilated meteorological observations from the NASA’s GEOS-
5.17 This model was run for 2011 with a grid resolution of 2.0 degrees x 2.5 degrees (latitude-
longitude). The predictions were used to provide one-way dynamic boundary concentrations at
one-hour intervals and an initial concentration field for the CAMx simulations. The 2011
boundary concentrations from GEOS-Chem were used for the 2011 and 2028 model simulations.
The procedures for translating GEOS-Chem predictions to initial and boundary concentrations
are described elsewhere (Henderson, 2014). More information about the GEOS-Chem model and
other applications using this tool is available at: http://www-as.harvard.edu/chemistry/trop/geos.
The initial and boundary condition files were used, as obtained from EPA. When CAMx was
updated from 6.32 to 6.40 the species in the secondary organic aerosol (SOA) scheme changed.
The SOA5, SOA6, and SOA7 were removed and SOA3 and SOA4 were redefined. Neither EPA
nor this study will remap the boundary conditions to account for this change. EPA examined the
regional haze summary data for all Class I areas and found the total organic carbon (OC) species
(not just SOA) accounted for 1-5% of the boundary condition impairment at the Southeastern
15 https://ozoneaq.gsfc.nasa.gov/data/
16 The 2006 NLCD data are available at http://www.mrlc.gov/nlcd06_data.php
17 Additional information available at: http://gmao.gsfc.nasa.gov/GEOS/ and http://wiki.seas.harvard.edu/geos-
chem/index.php/GEOS-5
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Class I areas.18 This is a small impact on regional haze and the impact of SOA on regional haze
is even smaller.
18 Brian Timin, EPA Office of Air Quality Planning and Standards (OAQPS) personal communication October 11, 2018.
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Table 5-1. Overview of Routine Ambient Data Monitoring Networks
Monitoring Network Chemical Species Measured Sampling Period Data Availability/Source
The Interagency
Monitoring of Protected
Visual Environments
(IMPROVE)
Speciated PM2.5 and PM10 (see
species mappings); light
extinction data
1 in 3 days; 24-hour
average
http://vista.cira.colostate.edu/improve/Data/IMPROVE/improv
e_data.htm
Clean Air Status and
Trends Network
(CASTNET)
Speciated PM2.5, and O3 (see
species mappings)
Approximately 1-
week average
http://www.epa.gov/castnet/data.html
National Atmospheric
Deposition Program
(NADP)
Wet deposition (hydrogen
(acidity as pH), sulfate, nitrate,
ammonium, chloride, and base
cations (such as calcium,
magnesium, potassium and
sodium)), Mercury
1-week average http://nadp.sws.uiuc.edu/
Air Quality System
(AQS)
CO, NO2, O3, SO2, PM2.5, PM10,
lead (Pb), HAPs
Typically hourly
average to 24-hour
average
http://www.epa.gov/air/data/
Chemical Speciation
Network (CSN)
Speciated PM2.5 24-hour average http://www.epa.gov/ttn/amtic/amticpm.html
Photochemical
Assessment Monitoring
Stations (PAMS)
Varies for each of 4 station
types.
Varies by station http://www.epa.gov/ttn/amtic/pamsmain.html
National Park Service
Gaseous Pollutant
Monitoring Network
Acid deposition (Dry; SO42-,
NO3-, HNO3, NH4, SO2), O3,
meteorological data
Hourly http://www2.nature.nps.gov/ard/gas/netdata1.htm
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6.0 MODEL INPUT PREPARATION PROCEDURES
This section summarizes the procedures to be used in developing the meteorological, emissions,
and air quality inputs to the CAMx model for the VISTAS II modeling on the 12 km grids for the
annual 2011 period. The 12 km CAMx modeling databases are largely based on the EPA “el”
platform databases.
6.1 Meteorological Inputs
The meteorological inputs in EPA’s “el” platform will be used directly without revision. Details
of EPA’s annual 2011 meteorological model simulation and evaluation are provided in a separate
technical support document (EPA, 2014a), which can be obtained at:
http://www.epa.gov/ttn/scram/reports/MET_TSD_2011_final_11-26-14.pdf.
6.1.1 WRF Model Science Configuration
Version 3.4 of the WRF model ARW core (Skamarock, 2008) was used for generating the 2011
simulations. Selected physics options include Pleim-Xiu land surface model, Asymmetric
Convective Model Version 2 planetary boundary layer scheme, KainFritsch cumulus
parameterization utilizing the moisture-advection trigger (Ma and Tan, 2009), Morrison double
moment microphysics, and Rapid Radiative Transfer Model-Global (RRTMG) longwave and
shortwave radiation schemes (Iacono et al., 2008). The WRF model configuration was prepared
by EPA (EPA, 2014d).
6.1.2 WRF Input Data Preparation Procedures
The WRF model simulation was initialized using the 12km North American Model (NAM-12)
analysis product provided by the National Climatic Data Center (NCDC). Where NAM-12 data
were unavailable, the 40km Eta Data Assimilation System (EDAS) analysis (ds609.2) from the
National Center for Atmospheric Research (NCAR) was used. Analysis nudging for temperature,
wind, and moisture was applied above the boundary layer only. The model simulations were
conducted in 5.5 day blocks with soil moisture and temperature carried from one block to the
next via the Intermediate Processor for Pleim–Xiu for WRF (IPXWRF) program (Gilliam and
Pleim, 2010). Land use and land cover data were based on the 2006 National Land Cover
Database (NLCD2006) data.19 Sea surface temperatures at 1 km resolution were obtained from
the Group for High Resolution Sea Surface Temperatures (GHRSST) (Stammer, et al., 2003).
As shown in Table 4-2, the WRF simulations were performed with 35 vertical layers up to
50 mb, with the thinnest layers being nearest the surface to better resolve the planetary boundary
layer (PBL). The WRF 35-layer structure was collapsed to 25 layers for the CAMx air quality
model simulations, as shown in Table 4-2.
6.1.3 WRF Model Performance Evaluation
The WRF model performance evaluation is provided in EPA’s Meteorological Model
Performance for Annual 2011 WRF v3.4 Simulation documentation report (EPA, 2014d). The
WRF model evaluation approach was based on a combination of qualitative and quantitative
analyses. The quantitative analysis was divided into monthly summaries of 2-m temperature, 2-m
19 The 2006 NLCD data are available at http://www.mrlc.gov/nlcd06_data.php
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mixing ratio, and 10-m wind speed using the boreal seasons to help generalize the model bias
and error relative to a set of standard model performance benchmarks. The qualitative approach
was to compare spatial plots of model estimated monthly total precipitation with the monthly
PRISM precipitation.
6.1.4 WRFCAMx/MCIP Reformatting Methodology
The WRF meteorological model output data was processed to provide inputs for the CAMx
photochemical grid model. The WRFCAMx processor maps WRF meteorological fields to the
format required by CAMx. It also calculates turbulent vertical exchange coefficients (Kv) that
define the rate and depth of vertical mixing in CAMx. The methodology used by EPA to reform
the meteorological data into CAMx format is provided in documentation provided with the
wrfcamx conversion utility.20
The meteorological data generated by the WRF simulations were processed by EPA using
WRFCAMx v4.3 (Ramboll Environ, 2014) meteorological data processing program to create
model-ready meteorological inputs to CAMx. In running WRFCAMx, vertical eddy diffusivities
(Kv) were calculated using the Yonsei University (YSU) (Hong and Dudhia, 2006) mixing
scheme. Alpine used a minimum Kv of 0.1 m2/sec except for urban grid cells where the
minimum Kv was reset to 1.0 m2/sec within the lowest 200 m of the surface in order to enhance
mixing associated with the nighttime “urban heat island” effect. In addition, EPA invoked the
subgrid convection and subgrid stratoform stratiform cloud options in our wrfcamx run for 2011.
6.1.5 Windowing from EPA 12US2 to VISTAS_12
The meteorological data will be windowed from the EPA 12US2 domain onto the VISTAS_12
domain using a slightly modified version of the CAMx utility program “window”.21 The only
required change to the distributed version program is to allow the program to window three-
dimension files instead of just two-dimensional files.
6.2 Emission Inputs
6.2.1 Available Emissions Inventory Datasets
The base year emission inventories to be used in the VISTAS II modeling study will be based on
EPA’s 2011el modeling platform without exception. Complete documentation for the 2011
emissions used for EPA’s regional haze modeling are described in the documents, “Preparation
of Emissions Inventories for the Version 6.3, 2011 Emissions Modeling Platform.”
Emissions for the 2028 base year will include EPA 2028el projections for most sectors (onroad
and nonroad mobile sources, marine, aircraft, railroad, fires, nonpoint area, biogenic, and
international sources) augmented with updated EGU and non-EGU point source emission
estimates provided by SESARM.
Documentation on EPA’s 2028el platform can be found in “Technical Support Document (TSD)
Updates to Emissions Inventories for the Version 6.3 2011 Emissions Modeling Platform for the
20 http://www.camx.com/getmedia/7f3ee9dc-d430-42d6-90d5-dedb3481313f/wrfcamx-11jul17.tgz
21 http://www.camx.com/getmedia/88755b80-6992-4f07-bcaa-596d05e1b4b8/window-6may13_1.tgz
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Year 2028”. Adjustments planned for the SESARM adjusted source categories are documented
below.
Outside of the VISTAS states, source categories and their associated emissions will be taken
directly from the EPA 2028el modeling platform. The exceptions to this will be:
• For EGU sources where data obtained from the projections to 2028 for EGU point source
emissions by the ERTAC EGU projection tool 22 from the most recent CONUS 16.0/16.1
runs will be used, based on state direction.
• For non-SESARM states providing emissions updates for facilities of interest based on
the Area Of Influence Analysis.
6.2.2 2011 Base Year Emissions
The emissions data in the 2011 platform are primarily based on the 2011NEIv2 for point sources,
nonpoint sources, commercial marine vessels (CMV), nonroad mobile sources and fires. The
onroad mobile source emissions are similar to those in the 2011NEIv2, but were generated using
the released 2014a version of the Motor Vehicle Emissions Simulator (MOVES2014a). Fugitive
dust emissions from anthropogenic sources (i.e., agricultural tilling and unpaved roads) are
included in the nonpoint sector of the inventory, but wind-blown dust from natural sources is not
accounted for in the inventory.
2011 CAMx-ready emission inputs were generated by EPA mainly by the SMOKE and BEIS
emissions models. CAMx requires two emission input files for each day: (1) low level gridded
emissions that are emitted directly into the first layer of the model from sources at the surface
with little or no plume rise; and (2) elevated point sources (stacks) containing stack parameters
from which the model can calculate plume rise. As noted earlier, EPA’s 2011el emission
platform in CAMx-ready format will be used without exception.
6.2.3 2028 Projection Year Emissions
Certain 2011 emission sectors were also projected by EPA to 2028 using various sector
dependent methodologies. Onroad and nonroad mobile source emissions were created for 2028
using the MOVES and NONROAD models, respectively. Nonpoint area source emissions were
prepared using growth and control factors simulating changes in economic conditions and
environmental regulation anticipated to be fully implemented by calendar year 2028. For these
categories, Alpine will be using EPA’s estimates from the 2028el platform, unless a VISTAS
state provides an update that is authorized by the SESARM contract.
Projections to 2028 for EGU and non-EGU point source emissions for 2028 will be derived from
files produced by the ERTAC EGU projection tool from the most recent CONUS runs (2.7, 16.0,
and 16.1) and from SESARM review of EPA 2028el emissions augmented with state-provided
growth and control adjustments, respectively. Additionally, states will also review EPA’s most
recent 2028 projected emissions from the 2016 modeling platform.23 ERG will review the
22 http://www.marama.org/2013-ertac-egu-forecasting-tool-documentation
23 https://www.epa.gov/air-emissions-modeling/2016v1-platform
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emissions adjustments and work with states to ensure that the revised values are reasonable.
ERG will also document the source of the revised 2028 emissions.
ERG will prepare state-specific summary comparisons of EPA’s 2028v6.3el modeling platform
emissions to the 2023v6.3en modeling platform emissions for stationary electricity generating
unit (EGU) and non-EGU stationary point sources to facilitate review by each VISTAS state.
The summaries between the two inventories will be grouped by Emission Inventory System
(EIS) facility, emissions unit, process, and release point identifiers and source classification code
(SCC) for annual emissions of:
• Oxides of nitrogen (NOx);
• Volatile organic compounds (VOC);
• Primary particulate matter less than or equal to 2.5 microns in aerodynamic diameter
(PM2.5-PRI);
• Primary particulate matter less than or equal to 10 microns in aerodynamic diameter
(PM10-PRI);
• Carbon monoxide (CO);
• Sulfur dioxide (SO2); and
• Ammonia (NH3).
If the 2023v6.3en emissions are selected for the final 2028 emissions inventory, ERG will
document these updates.
ERG will work with SESARM on the final format of the comparison tables, including additional
fields that may be useful for review, such as: facility information; SCC descriptions; unit,
process, and release point descriptions; ORIS boiler identifiers; control information; and absolute
and percentage differences between the two emissions inventories. All data will be provided in a
single Excel file, unless the file size is prohibitive, at which point ERG will work with SESARM
on the best way to divide the data across multiple files.
6.2.3.1 EGU Point Source Emissions
For EGU sources only, the ERG/Alpine team will use an already-obtained version of the 2028
emissions forecast, the 2028 projected emissions based on EPA’s 2016 modeling platform, and
associated files produced by the ERTAC EGU projection tool from the most recent CONUS 2.7,
16.0, and 16.1 runs available. The specific runs for each EGU are documented in the Task 2B
(for SESARM states) and Task 3B (for non-SESARM states) reports. The team will prepare
state-specific summary comparisons of EPA’s 2028v6.3el modeling platform emissions to
EPA’s 2023v6.3en modeling platform emissions to the ERTAC 2028 modeling platform
emissions for EGU point sources to facilitate the VISTAS state review. The summaries will be
produced in Microsoft Excel format grouped by EIS facility, emissions unit, process, and release
point identifiers, ORIS ID, and SCC for annual emissions of NOX, VOC, PM2.5-PRI, PM10-PRI,
CO, SO2, and NH3 between the two emissions inventories.
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ERG will work with SESARM on the final format of the comparison tables, including additional
fields that may be useful for review, such as: facility information; SCC descriptions; unit,
process, and release point descriptions; ORIS boiler identifiers; control information; and absolute
and percentage differences between the two emissions inventories.
SESARM will identify for ERG in the final comparison tables which emissions projection
platform (e.g., EPA 2023en, EPA 2028el, ERTAC EGU, or state provided) should be used in the
final 2028 modeling file preparation. For any individual EGU source, only a single platform
should be selected. In other words, emissions from one platform cannot be mixed with emissions
from another platform at the same unit.
6.2.3.2 Non-EGU Point Source Emissions
Similar to the work being conducted for EGU point sources, ERG will update the 2028 non-EGU
point source projection year mass emissions inventories based on the information collected from
SESARM’s review of prepared comparison tables. All revisions will be documented to account
for changes in emissions due to retirements, control enhancements, and/or fuel switches, as well
as any additional metadata to describe the data. For certain situations, a state may wish to
develop their own revised 2028 point sources emissions inventory using updated growth and/or
control factors on the 2011 point sources emissions inventory. In these cases, ERG will work
with the state agencies to provide the data into the format needed for integration.
6.2.3.3 Nonpoint Area, Onroad, and Nonroad Mobile Source Emissions
Emissions data for 2028 nonpoint area, onroad mobile, and nonroad mobile sources will be used
from the 2011/2028el modeling platform. These sources will be spatially allocated to the grid
using an appropriate surrogate distribution (e.g., population for home heating, etc.) and will be
temporally allocated by month, by day of week, and by hour of day using the EPA source-
specific temporal allocation factors. The SMOKE source-specific CB6r4 speciation allocation
profiles will also be used for all categories.
6.2.3.4 Biogenic Source Emissions
Biogenic emissions were generated by EPA using the BEIS biogenic emissions model within
SMOKE. BEIS uses high resolution GIS data on plant types and biomass loadings and the WRF
surface temperature fields, and solar radiation (modeled or satellite-derived) to develop hourly
emissions for biogenic species on the 12 km grids. BEIS generates gridded, speciated, temporally
allocated emission files. EPA’s 2011 biogenic emissions will be used for the 2028 modeling
platform.
6.2.3.5 Wildfires, Prescribed Burns, Agricultural Burns
Fire emissions in 2011NEIv2 were developed based on Version 2 of the Satellite Mapping
Automated Reanalysis Tool for Fire Incident Reconciliation (SMARTFIRE) system (Sullivan, et
al., 2008). SMARTFIRE2 was the first version of SMARTFIRE to assign all fires as either
prescribed burning or wildfire categories. In past inventories, a significant number of fires were
published as unclassified, which impacted the emissions values and diurnal emissions pattern.
Recent updates to SMARTFIRE include improved emission factors for prescribed burning.
These emissions as prepared by EPA will be included in both the 2011 and 2028 emission
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platforms. EPA’s 2011 fire emissions will be used for the 2028 modeling platforms. It should be
noted that there were large wildfires in the Okefenokee Swamp and Eastern North Carolina in
2011. However, contributions from these wildfires should not impact the development of
reasonable progress goals since EPA’s new 20% most impaired days metric removes IMPROVE
days that were significantly impacted by these wildfires from the analysis.
6.3 Emissions Processing
CAMx requires detailed emissions inventories containing temporally allocated (i.e., hourly)
emissions for each grid-cell in the modeling domain for a large number of chemical species that
act as primary pollutants and precursors to secondary pollutants. Annual emission inventories for
2011 and 2028 will be preprocessed into SMOKE-ready modeling system (Houyoux et al., 2000)
inputs for eventually additional processing and use in CAMx. For this analysis, CAMx will be
operated using Version 6 revision 4 of the Carbon Bond chemical mechanism (CB6r4).
For emission segments that are unchanged from the EPA distribution, the emission will be
windowed from the EPA 12US2 domain onto the VISTAS_12 domain using the CAMx
“window”24 utility program. For VISTAS state specific emission segments, the emissions will be
developed on the VISTAS_12 domain.
Steps necessary to prepare SMOKE-ready input files from the mass emissions data is outlined in
the VISTAS II workplan, Task 2. In that task, Alpine will ensure that annual emission changes
submitted or authorized by SESARM are carried through to all relevant input files consistent
with EPA’s 2011 and 2028 v6.3el platform processing. Upon the completed development of
these new input files, Alpine will use EPA’s modeling platform scripts, with the updated input
files from this task, to generate CAMx photochemical model Version 6.40-ready inputs using the
SMOKE Modeling System.
The CMAQ and CAMx models require hourly emissions of specific gas and particle species for
the horizontal and vertical grid cells contained within the modeled region (i.e., modeling
domain). To provide emissions in the form and format required by the model, it is necessary to
“pre-process” the “raw” emissions (i.e., emissions input to SMOKE) for the sectors described
above. In brief, the process of emissions modeling transforms the emissions inventories from
their original temporal resolution, pollutant resolution, and spatial resolution into the hourly,
speciated, gridded resolution required by the air quality model.
The emission processing for this project will take two different “paths” as shown in Figure 6-1.
For emission segments that are being updated for the project, the emissions will be processed
using SMOKE version 3.7 with the emissions being output directly into CAMx format for the
VISTAS_12 domain. For emission segments that are unchanged from the EPA simulation the
emissions will be converted from the EPA supplied CMAQ format into CAMx format using the
CMAQtoCAMx processor and windowed onto the VISTAS_12 domain using the “WINDOW”
program. The CMAQ2CAMx converter reformats the files, converts units, and transforms the
CMAQ in-line elevated emissions into CAMx elevated format and low level files into CAMx
24 http://www.camx.com/getmedia/88755b80-6992-4f07-bcaa-596d05e1b4b8/window-6may13_1.tgz
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format. As a final step before running the CAMx model, the low-level emissions will be merged
into the single low level and elevated files.
Figure 6-1. Emission Processing Paths
While the 2028 projection year non-EGU and EGU point source inventory will be updated to
reflect requested changes by SESARM, the steps associated with the emissions processing of
these files remains the same as EPA’s methods for the 2028 regional haze modeling analysis.
Details of the temporal, spatial, and speciation data and methods are described in EPA’s
technical support document for the development of the 2028 platform.25
Other than the preparation of data for an additional modeling domain (VISTAS_12) for this
analysis, all other emissions processing steps, methods, and ancillary data and associations will
be identical to EPA’s documented processing steps.
25 https://www.epa.gov/sites/production/files/2017-11/documents/2011v6.3_2028_update_emismod_tsd_oct2017.pdf
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No plume-in-grid (PiG) subgrid-scale plume treatment will be used in this project.
Scripts to perform the emissions merging of the appropriate biogenic, onroad, nonroad, nonpoint
area, low-level, fire, and point emission files will be written to generate the CAMx-ready two-
dimensional day and domain-specific hourly speciated gridded emission inputs. The point source
and, as available elevated fire, emissions would be processed into the day-specific hourly
speciated emissions in the CAMx-ready point source format.
6.3.1 QA/QC of CAMx-Ready Emission Files
For quality assurance of the emissions modeling steps, emissions totals for all species across the
entire model domain will be output as reports that are then compared to reports generated by
SMOKE on the input inventories to ensure that mass is not lost or gained during the emissions
modeling process.
In addition to the CAMx-ready emission input files generated for each hour of all days modeled
in the annual 2011 or 2028 modeling period, a number of QA files may be prepared and used to
check for gross errors in the emissions inputs. The model-ready emissions will be imported into
visualization tools and Alpine will examine both the spatial and temporal distribution of the
emission to investigate the quality and accuracy of the emissions inputs.
• Visualizing the model-ready emissions with the scale of the plots set to a very low value,
Alpine can determine whether there are areas omitted from the raw inventory or if
emissions sources are erroneously located in water cells;
• Spot-checking the holiday emissions files to confirm that they are temporally allocated
like Sundays;
• Producing pie charts emission summaries that highlight the contribution of each
emissions source component (e.g. nonroad mobile); and
• Normalizing the emissions by population for each state will illustrate where the
inventories may be deficient and provide a reality check of the inventories.
State inventory summaries prepared prior to the emissions processing will be used to compare
against SMOKE output report totals generated after each major step of the emissions generation
process. To check the chemical speciation of the emissions to CB6 species, Alpine will compare
reports generated with SMOKE to target these specific areas of the processing. For speciation,
the inventory state import totals will be compared against the same state totals with the
speciation matrix applied.
The quantitative QA analyses often reveal significant deficiencies in the input data or the model
setup. It may become necessary to tailor these procedures to track down sources of any identified
major problem. As such, Alpine can only outline the basic quantitative QA steps that are
performed by Alpine to reveal the underlying problems with the inventories or processing.
Standard inventory assessment methods may be employed to generate the future year emissions
data QA files including, but not limited to: (a) visualizing the model-ready emissions
graphically, (b) spot-checking the holiday emissions files to confirm that they are temporally
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allocated like Sundays, (c) producing pie charts emission summaries for each source category,
and (d) normalizing the emissions by population for each state to reveal where the future year
inventories may be suspect. Of particular importance will be the comparison of the 2011 base
year and 2028 future year emissions by source category to make sure the expected changes have
been appropriately accounted for in the modeling inventories.
The resultant CAMx model-ready emissions will be subjected to a final QA using spatial maps to
assure that: (1) the emissions were merged properly; (2) CAMx inputs contain the same total
emissions; and (3) to provide additional QA/QC information.
Emissions are processed by major source category in several different “streams”, including
nonpoint area sources, onroad mobile sources, nonroad mobile sources, biogenic sources, non-
CEM point sources, CEM point sources using day-specific hourly emissions, and emissions from
fires. Separate Quality Assurance (QA) and Quality Control (QC) will be performed for each
stream of emissions processing and in each step following the procedures outlined in the project
QAPP. SMOKE includes advanced quality assurance features that include error logs when
emissions are dropped or added. In addition, Alpine will generate visual displays that include:
• Spatial plots of the hourly emissions for each major species (e.g., NOX, VOC, some
speciated VOC, SO2, NH3, PM and CO).
• Summary tables of emissions for major species for each grid and by major source
category.
• This QA information will be examined against the original point and nonpoint area
source data and summarized in an overall QA/QC assessment.
6.4 Photochemical Modeling Inputs
6.4.1 CAMx Science Configuration and Input Configuration
This section describes the model configuration and science options to be used in the VISTAS II
modeling effort. Version 6.40 of CAMx will be used for this modeling.
CAMx is a three-dimensional grid-based Eulerian air quality model designed to simulate the
formation and fate of oxidant precursors, primary and secondary particulate matter
concentrations, and deposition over regional and urban spatial scales (e.g., the contiguous U.S.).
Consideration of the different processes (e.g., transport and deposition) that affect primary
(directly emitted) and secondary (formed by atmospheric processes) pollutants at the regional
scale in different locations is fundamental to understanding and assessing the effects of
emissions on air quality concentrations.
Figure 4-1 presented the geographic extent of the modeling domains (12US2 and VISTAS_12)
that will be used for air quality modeling in this analysis. The 12US2 domain covers the 48
contiguous states along with the southern portions of Canada and the northern portions of
Mexico. The VISTAS_12 domain covers the continental US eastward from the western extent of
Texas along with the southern portions of Canada and the northern portions of Mexico. As
discussed later, the limited coverage of Canada and Mexico is an important consideration when
interpreting the modeling results. This modeling domain contains 25 vertical layers with a top at
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about 17,550 meters, or 50 millibars (mb), and horizontal grid resolution of 12 km x 12 km. The
model simulations produce hourly air quality concentrations for each 12 km grid cell across the
modeling domain.
For the simulations that use the EPA 12US2 domain, the model will be applied using the same
time segments as EPA. The model will be applied from December 22, 2010 through April 30,
2011 and from April 21, 2011 through December 31, 2011. The beginning of each segment,
December 21-31, 2010 for the first segment and April 21-30, 2011 for the second segment are
used as spin-up periods and will not be analyzed.
For the simulation on the VISTAS_12 domain, the model will be applied quarterly using the
definitions in Table 6-1. The initial conditions for each quarter, and hourly boundary conditions
will be extracted from the CAMx version 6.40 simulations performed over the EPA 12US2
CONUS domain.
Table 6-1. VISTAS II Simulation Periods
Quarter Number Starting Date Ending Date
1 December 22, 2010 March 31, 2011
2 March 15, 2011 June 30, 2011
3 June 15, 2011 September 30, 2011
4 September 15, 2011 December 31, 2011
CAMx requires a variety of input files that contain information pertaining to the modeling
domain and simulation period. These include gridded, hourly emissions estimates and
meteorological data, and boundary concentrations. Separate emissions inventories will be
prepared for the 2011 base year and the 2028 base case. Meteorological fields will be specified
for the 2011 base year model application and remained unchanged for the future-year model
simulations.26 The IC/BC for VISTAS_12 in 2028 will be based on 12US_2 domain as
mentioned in section 5.5.2.
Ten CAMx model runs, associated with up to 250 tagged sources, are currently planned for this
analysis. The simulations are summarized in Table 6-2.
Table 6-2. CAMx Simulations for the VISTAS II Project
Simulation
Number Description
CAMx
Version Grid Task Time
1 EPA 2011el Confirmation 6.32 12US2 6.2 EPA 1,2*
2
EPA 2011el saving 3-D average
for VISTAS12 IC/BC Extracts 6.40 12US2 6.2 EPA 1,2
3 EPA 2028el Confirmation 6.32 12US2 6.3 EPA 1,2
4
VISTAS 2028 saving 3-D average
for VISTAS12 IC/BC extracts 6.40 12US2 6.3 EPA 1,2
26 The CAMx annual simulations for 2011 and 2028 were each performed using two time segments (January 1 through April 30,
2011 with a 10-day ramp-up period at the end of December 2010 and May 1 through December 31, 2011 with a 10-day ramp-
up period at the end of April 2011).
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Table 6-2. CAMx Simulations for the VISTAS II Project
Simulation
Number Description
CAMx
Version Grid Task Time
5
EPA 2011el saving 3-D average
for state domains IC/BC extracts 6.40 VISTAS_12 6.2 Q1,2,3,4
6
VISTAS 2028 saving 3-D average
for state domain IC/BC extracts 6.40 VISTAS_12 6.3 Q1,2,3,4
7
VISTAS 2028 PSAT with selected
sources 1-50 tagged 6.40 VISTAS_12 7 Q1,2,3,4
8
VISTAS 2028 PSAT with selected
sources 51-100 tagged 6.40 VISTAS_12 7 Q1,2,3,4
9
VISTAS 2028 PSAT with selected
sources 101-150 tagged 6.40 VISTAS_12 7 Q1,2,3,4
10
VISTAS 2028 PSAT with selected
sources 151-200 tagged 6.40 VISTAS_12 7 Q1,2,3,4
11
VISTAS 2028 PSAT with selected
sources 201-250 tagged 6.40 VISTAS_12 7 Q1,2,3,4
*EPA twice annual segments from December 22, 2010 through April 30, 2011 and April 21, 2011 through December 31, 2011.
6.4.2 VISTAS_12 Boundary And Initial Conditions
Boundary and initial conditions for the VISTAS_12 domain will be extracted from simulations
using the EPA 12US2 domain. For the 2011 baseline simulation, the EPA 2011el platform for
the 12US2 domain will be run using CAMx 6.40 and the resultant three-dimensional outputs will
be saved. For the 2028 future year simulation, the EPA 2028el point source emissions will be
reprocessed to include updated point source emissions, and CAMx 6.40 will be run saving three-
dimensional outputs. The boundary and initial conditions for the VISTAS_12 domain will be
extracted from the respective three-dimensional output files using the CAMx BNDEXTR
program.
6.4.3 VISTAS_12 Ozone Column
EPA developed new ozone column data for their more current 2023en simulation. This more
recent data will be used for the final VISTAS 2011 and 2028 modeling. The ozone column data
for the VISTAS_12 domain will be windowed from the EPA 12US2 domain. The ozone column
data is a simple text file and new code will be developed to extract data for the smaller
VISTAS_12 domain.
6.4.4 Photolysis Rates
The final VISTAS 2011 and 2028 simulations will use the updated photolysis data EPA
developed for the 2023en simulation. The EPA photolysis rates used will be unchanged in the
VISTAS_12 domain.
6.4.5 CAMx Land Use
The land use file for the VISTAS_12 domain will be windowed from the EPA 12US2 domain.
The land use file is a simple text file and new code will be developed to extract data for the
smaller VISTAS_12 domain.
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6.5 EPA 2011 and 2028 Base Case Confirmation
The numerics in photochemical grid models are very complex and it is typical to get slightly
different model concentrations based on the version of the computer and compilers. When
comparing simulations, it is critical to isolate the changes in concentrations to the changes in the
model inputs, and not on the computing details (i.e., compiler version, computer architecture,
parallelization options). This is especially problematic when looking at particulate matter, since
the particulate treatments have multiple pathways, and small concentration differences can lead
to different pathways through the code and different concentrations.
Sources of the difference can come from the options used in CAMx compilation, the version of
the compiler, the compiler vendor, and how the model calculation is split onto different
processors (parallelization).
Alpine will execute two confirmation runs, one for the 2011el base year and one for the 2028el
base case, to confirm the contract team’s ability to replicate EPA’s results and to ensure that the
EPA data, models, and scripts operated in a consistent manner as EPA’s procedure.
6.5.1 Differences Between EPA And VISTAS Simulations
EPA ran the 2011v6.3el platform on EPA’s supercomputer with the model configured to use four
(4) processor nodes with 16 processors per node. The use of multiple processor nodes with
multiple processors per node is efficient on the EPA supercomputer due to the low latency
interconnect between the nodes. On more typical computer clusters with the nodes
interconnected with Ethernet, like the Alpine cluster and most likely the State and stakeholder
clusters, the latency between nodes is sufficiently high that it is inefficient to spread processing
between nodes. Our experience with the EPA platform has shown that on an Ethernet connected
cluster with 12 Intel XEON processors per node and hyperthreading enabled it is most efficient
to use a single node configured with 10 Message Passing Interface (MPI) instances, each with
2 OpenMP threads.
EPA used the Intel FORTRAN compiler. Alpine, and the CAMx developers, use the Portland
Group (PGI) FORTRAN compiler. The PGI compiler has been the standard compiler for CAMx
applications for many years and it’s anticipated this compiler will be more widely used by the
States and stakeholders. The version of CAMx 6.32 EPA distributed with the 2011el platform
will be recompiled on the Alpine computer system and used for the confirmation.
As noted in Section 5.5.1, EPA ran the model in two time segments. The first segment, typically
used only for PM applications, runs from December 22, 2010 through April 30, 2011. The
second segment runs from April 21, 2011 through December 31, 2011. The VISTAS
confirmation run will use the same two segments. December 22-31, 2010 and the April portion
of the second segment are spin-ups and will not be analysed.
6.5.2 Confirmation Methodology
The simulations on the Alpine computer cluster and the EPA computer will be based on hourly
differences in ozone, PM2.5, POC, Particulate Nitrate and Particulate Sulfate. The metric for
comparison will be the absolute difference (Equation 1) and percent difference (Equation 2)
defined as:
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(Equation 1) �𝐶𝐶𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣−𝐶𝐶𝑒𝑒𝑒𝑒𝑣𝑣�
(Equation 2) �𝐶𝐶𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣−𝐶𝐶𝑒𝑒𝑒𝑒𝑣𝑣��𝐶𝐶𝑒𝑒𝑒𝑒𝑣𝑣�
Where Cepa is the concentration at each grid cell hour for the EPA simulation and Cvistas is the
concentration at each grid cell hour for the simulation on the Alpine computers.
The comparison will be done both graphically (e.g., scatter density plots) and quantitatively (e.g.,
residual distributions) for reviewed concentrations. Analysis products will be hourly spatial plots
of the absolute differences. Should significant differences be noted between the confirmation
runs and EPA’s original simulations, Alpine will generate an electronic appendix of the spatial
plots and discuss with SESARM and others as requested. If it is determined that noted
differences are the result of modeling errors, Alpine will propose to SESARM recommended
approaches to correct the issues and will correct configurations based on negotiation action.
The following confirmation benchmark runs will be performed:
1. Benchmark Run #1 - EPA 2011 with CAMx_6.32 (CONUS) vs. Alpine 2011 with
CAMx_6.32 (CONUS), as documented in Benchmark Report #1.
2. Benchmark Run #2 - EPA 2028 with CAMx_6.32 (CONUS) vs. Alpine 2028 with
CAMx_6.32 (CONUS), as documented in Benchmark Report #1.
3. Benchmark Run #3 - Alpine 2011 with CAMx_6.32 (CONUS) vs. Alpine 2011 with
CAMx_6.40 (CONUS), as documented in Benchmark Report #2.
4. Benchmark Run #4 - Alpine 2028 with CAMx_6.32 (CONUS) vs. Alpine 2028 with
CAMx_6.40 (CONUS), as documented in Benchmark Report #4.
5. Benchmark Run #5 - Alpine 2011 with CAMx_6.40 (CONUS) vs. Alpine 2011 with
CAMx_6.40 (VISTAS), as documented in Benchmark Report #3.
6. Benchmark Run #6 - Alpine 2028 with CAMx_6.40 (CONUS) vs. Alpine 2028 with
CAMx_6.40 (VISTAS), as documented in Benchmark Report #5.
7. Benchmark Run #7 - Alpine 2028elv3 with CAMx_6.40 (VISTAS) vs. Alpine 2028elv5
with CAMx_6.40 (VISTAS), as documented in Benchmark Report #6.
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7.0 MODEL PERFORMANCE EVALUATION
An operational model performance evaluation will be conducted for total fine particulate matter
(PM2.5), PM2.5 species components (e.g., SO4, NO3, NH4, EC, and OC), measured gas phase
species (e.g., O3, HNO3, SO2, VOCs, NO2, and NO), and speciated components of light
extinction to examine the ability of the CAMx v6.40 modeling system to simulate 2011
measured concentrations. This evaluation will focus on graphical analyses and statistical metrics
of model predictions versus observations. Note that as EPA did not publish an evaluation of
PM2.5 gas phase species in their 2028 regional haze modeling we will not have a basis for
comparison of these metrics.
The CAMx 2011 base case model estimates will be compared against the observed
concentrations to establish that the model is capable of reproducing the current year observed
concentrations so that it can be considered a reliable tool for estimating future year PM and
regional haze levels.
The model evaluation will focus on the ability of the model to predict visibility-reducing PM at
VISTAS Class I areas (represented by IMPROVE monitoring sites). The analysis will look at
monthly and seasonal average PM species component performance at IMPROVE and other PM
monitoring networks, and performance on the 20% most impaired (and 20% clearest) days at
individual IMPROVE sites. This will provide a comprehensive assessment of the components
that make up visibility performance.
The measured concentrations of PM components such as nitrate on the 20% most impaired days
at many Class I areas are extremely small. Numerous Class I areas in the Eastern U.S. have
average nitrate observations (on the 20% most impaired days) of less than 1 μg/m3. This makes it
challenging to correctly model observed visibility. Assumptions regarding particular emissions
categories and boundary conditions can have a large impact on model performance. Even when
model performance appears to be accurate, it is difficult (without further modeling and analysis)
to determine if the answers observed are right for the right reasons (for example, when the
extinction is dominated by modeled boundary conditions).
7.1 Model Performance Evaluation
7.1.1 Overview of EPA Model Performance Evaluation Recommendations
EPA current (EPA, 2007) and draft (EPA, 2014e) ozone, PM, and regional haze modeling
guidance recommendations for model performance evaluation (MPE) describes a MPE
framework that has four components:
• Operation evaluation that includes statistical and graphical analysis aimed at determining
how well the model simulates observed concentrations (i.e., does the model get the right
answer).
• Diagnostic evaluation that focuses on process-oriented evaluation and whether the model
simulates the important processes for the air quality problem being studied (i.e., does the
model get the right answer for the right reason).
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• Dynamic evaluation that assess the ability of the model air quality predictions to correctly
respond to changes in emissions and meteorology.
• Probabilistic evaluation that assess the level of confidence in the model predictions
through techniques such as ensemble model simulations.
EPA’s guidance notes that there is no single definitive test for evaluating model performance.
All of the tests mentioned here have strengths and weaknesses. Further, even with a single
performance test, it is not appropriate to assign “bright line” criteria that distinguish between
adequate and inadequate model performance. In this regard, EPA recommends that a “weight of
evidence” approach be used to determine whether a particular modeling application is valid for
assessing the future attainment status of an area.
EPA recommends that air agencies conduct a variety of performance tests and weigh them
qualitatively to assess model performance. Provided suitable databases are available, greater
weight should be given to those tests which assess the model capabilities most closely related to
how the model is used in the analysis (i.e. tests that provide insight into the accuracy of the
model’s relative response to emissions reductions). Generally, additional confidence should be
attributed to model applications in which a variety of the tests described here are applied and the
results indicate that the model is performing well.
From an operational standpoint, EPA recommends that air agencies compare their evaluation
results against similar modeling exercises to ensure that the model performance approximates the
quality of other applications. Recent literature reviews (Simon et al, 2012, Emery 2017)
summarized photochemical model performance for applications published in the peer-reviewed
literature between 2006 and 2012.
Because this 2011 VISTAS II modeling is using a CAMx 2011 modeling database developed by
EPA, Alpine will also include by reference the air quality modeling performance evaluation as
conducted by EPA (EPA, 2017b) on the national 12km domain.
Alpine will review EPA’s current operational MPE for particulate matter (PM2.5 species
components, coarse PM, and total PM2.5) and light extinction (total and species components) to
compare the ability of the CAMx v6.40 modeling system to simulate 2011 measured
concentrations. Using a combination of the Atmospheric Model Evaluation Tool (AMET) and
internal scripts used by Alpine, comprehensive MPE statistics and graphics from the 2011
CAMx simulation using data from the IMPROVE network will be prepared in formats that will
be accessible for stakeholder review and use. Alpine will use the current IMPROVE equation
(see Section 8) inclusive of the monthly relative humidity function [f(RH)] values for both
observed and modeled data to develop performance statistics at each IMPROVE monitor in the
VISTAS_12 domain.
7.1.2 VISTAS II Calculated Model Evaluation Statistics
In order to estimate the ability of CAMx to replicate the 2011 base year concentrations of
particulate matter, an operational model performance evaluation will be conducted. For this
evaluation, mean bias and normalized mean bias, mean error and normalized mean error, and
Pearson’s correlation coefficient will be used and directly compared to EPA’s results using these
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same statistics. Mean fractional bias, mean fractional error, and root mean squared error may
also be calculated but as these statistics were not calculated by EPA in its evaluation, there will
be no basis for comparison for these metrics.
Mean bias (MB) is the average difference between predicted (P) and observed (O) concentrations
for a given number of samples (n): 𝑀𝑀𝑀𝑀(𝜇𝜇𝜇𝜇 𝑚𝑚−3 𝑜𝑜𝑜𝑜 𝑀𝑀𝑚𝑚−1 )= 1𝑛𝑛�(𝑃𝑃𝑣𝑣−𝑂𝑂𝑣𝑣)𝑛𝑛𝑣𝑣=1
Mean error (ME) is the average absolute value of the difference between predicted and observed
concentrations for a given number of samples: 𝑀𝑀𝑀𝑀(𝜇𝜇𝜇𝜇 𝑚𝑚−3 𝑜𝑜𝑜𝑜 𝑀𝑀𝑚𝑚−1 )= 1𝑛𝑛�|𝑃𝑃𝑣𝑣−𝑂𝑂𝑣𝑣|𝑛𝑛𝑣𝑣=1
Normalized mean bias (NMB) is the sum of the difference between predicted and observed
values divided by the sum of the observed values: 𝑁𝑁𝑀𝑀𝑀𝑀(%)= ∑(𝑃𝑃−𝑂𝑂)𝑛𝑛1∑(𝑂𝑂)𝑛𝑛1 ∗100
Normalized mean error (NME) is the sum of the absolute value of the difference between
predicted and observed values divided by the sum of the observed values: 𝑁𝑁𝑀𝑀𝑀𝑀(%)= ∑|𝑃𝑃−𝑂𝑂|𝑛𝑛1∑(𝑂𝑂)𝑛𝑛1 ∗100
Pearson’s correlation coefficient (r) is defined as: 𝑜𝑜=∑(𝑃𝑃𝑣𝑣−𝑃𝑃)(𝑂𝑂𝑣𝑣−𝑂𝑂)𝑛𝑛𝑣𝑣=1�∑(𝑃𝑃𝑣𝑣−𝑃𝑃)2𝑛𝑛𝑣𝑣=1 �∑(𝑂𝑂𝑣𝑣−𝑂𝑂)2𝑛𝑛𝑣𝑣=1
Mean Fractional Bias (MFB) is defined as:
𝑀𝑀𝑀𝑀𝑀𝑀(%)= 2𝑁𝑁��𝑃𝑃−𝑂𝑂𝑃𝑃+𝑂𝑂�𝑁𝑁
1 × 100
Mean Fractional Error (MFE) is defined as:
𝑀𝑀𝑀𝑀𝑀𝑀(%)= 2𝑁𝑁��|𝑃𝑃−𝑂𝑂|𝑃𝑃+𝑂𝑂�𝑁𝑁
1 × 100
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Root Mean Squared Error (RMSE) is defined as:
𝑅𝑅𝑅𝑅𝑀𝑀𝑀𝑀= �∑(𝑃𝑃−𝑂𝑂)2𝑁𝑁1 𝑁𝑁
Model predictions of PM species will be paired in space and time with observational data from
the IMPROVE monitoring network. These results will be organized by IMPROVE monitor and
season (winter (DJF), spring (MAM), summer (JJA), and fall (SON)).
ERG/Alpine expects the model performance of the replicated 2011 CAMx run to be slightly
different from EPA published MPE metrics due to the differences in the version of CAMx being
used and the modeling domain. If performance is not comparable to EPA’s MPE, then data files
will be reviewed to determine the cause. If the difference is not explainable by the changes in
domain or model version, a call will be convened between ERG, Alpine, SESARM, and the
appropriate EPA staff to identify any inconsistencies and come to consensus on appropriate
corrective actions. Any of the metrics outside published proposed criteria levels will be noted as
part of the uncertainty associated with the modeling.
Additional statistical analysis may also be performed, as determined necessary. All statistics will
be calculated consistent with the respective pollutants NAAQS averaging time.
Tables and plots will be prepared for VISTAS and identified non-VISTAS IMPROVE monitors
as directed to demonstrate light extinction model performance in a graphical manner. Scatter
(with linear regression and r2 value), bugle, and soccer plots for all light extinction and speciated
components will be developed for the 20% most impaired and 20% clearest days for each
IMPROVE monitor in the VISTAS_12 modeling domain.
Alpine will develop the individual day-by-day and site-by-site stacked bar plots of total bext and
speciated components of bext for these most impaired and clearest days. Metrics and plots
generated for the most impaired days will be consistent with the latest definition of this
classification as “anthropogenically impaired” days as defined by EPA.
7.1.3 Model Performance Evaluation For Weekly Wet And Weekly Dry Deposition
Species
The modeling team will also perform a MPE for weekly wet deposition and weekly dry
deposition species collected in workplan Subtask 4.1. For this MPE, VISTAS CAMx deposition
values will be aggregated to appropriate time periods to match the various NADP monitoring
network’s concentration collection times. To prevent confounding the MPE, the networks with
different collection time (i.e., biweekly versus weekly) will be examined separately.
For wet deposition, NADP networks typically present measurements as concentration in mg/L,
which is equivalent to g/m3. These concentrations are then multiplied by the precipitation in
meters to yield wet deposition rates in units of g/m2. The CAMx wet deposition outputs are
provided in grams per hectare (g/ha), which will be converted to grams per meter squared (g/m2),
using the conversion of 1 ha = 10,000 m2, to have consistent units with the NADP monitoring
networks. CAMx estimates of wet deposition can also be adjusted to account for the error present
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in the model estimated precipitation through a ratio of the observed to estimated precipitation.27
Dry deposition values from CASTNET can be developed from the observed concentration
multiplied by a deposition velocity generated by the Multi-Layer Model (MLM)28 for the site.
The MLM generated deposition velocities are available for download with the CASTNET
observations.29
Annual mean MPE statistics, like the statistics for the base year MPE, will be developed for the
wet deposition and dry deposition species available. Analysis will also include scatter plots of
NADP network observations versus CAMx predictions, and their correlation (r), both annually
and by season. Statistical and scatter plots will also be examined by VISTAS states to provide
more refined MPE information to facilitate further use by the states.
Additionally, annual deposition totals will be produced from the VISTAS II base year modeling
and compared to the annual Total Deposition Maps developed by the NADP and EPA. These
total deposition maps are produced via a hybrid approach that combines the monitored data with
modeled data to produce a gridded map of total sulfate and nitrate depositions. While not entirely
observed truth, these hybrid estimates could provide the ability to evaluate generally the MPE for
the entire domain in areas where data availability is limited due to incomplete records from the
monitoring sites.
7.2 Performance Goals and Benchmarks
Establishment of performance goals and benchmarks for regulatory modeling is a necessary but
difficult activity. Here, performance goals refer to targets that Alpine believes a good performing
model should achieve, whereas performance benchmarks are based on historical model
performance measures for the best performing simulations. Performance goals are necessary in
order to provide consistency in model applications and expectations across the region and to
provide standardization in how much weight may be accorded modeling study results in the
decision-making process. These performance goals should not be interpreted as a “bright line”
where metrics below the value are judged as adequate and values above the line are unusable.
Rather they should be interpreted as the performance for a particular metric with good
performance should be more highly relied upon for decision making where a less well
performing pollutant may be less relied upon.
It is a problematic activity, though, because many areas present unique challenges and no one set
of performance goals is likely to fit all needs. Equally concerning is the very real danger that
modeling studies will be truncated when the ‘statistics look right’ before full assessment of the
model’s reliability is made. This has the potential from breeding built-in compensating errors as
modelers strive to get good statistics as opposed to searching for the explanations for poor
performance and then rectifying them.
27 Appel, K. W., et al. 2011. "A multi-resolution assessment of the Community Multiscale Air Quality (CMAQ) model v4. 7
wet deposition estimates for 2002–2006." Geoscientific Model Development 4.2 (2011): 357-371.
28 Meyers, T. P., Finkelstein, P., Clarke, J., Ellestad, T.G., and Sims, P.F. 1998. A Multilayer Model for Inferring Dry
Deposition Using Standard Meteorological Measurements. J. Geophys. Res., 103(D17): 22,645-22,661, DOI:
10.1029/98jd01564.
29 https://java.epa.gov/castnet/clearsession.do
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For this analysis, Alpine will pair model predictions in space and time with observational data
from the IMPROVE, CSN, and CASTNET monitoring networks. These results will be compared
by network and season (winter (Dec, Jan, Feb), spring (Mar, Apr, May), summer (Jun, Jul, Aug),
and fall (Sep, Oct, Nov)).
Recommended benchmarks for photochemical model performance statistics (Boylan, 2006;
Emery, 2017) will be used to assess the applicability of this modeled simulation for regulatory
purposes. The goal and criteria values noted in Table 7-1 below will be used for this study.
Table 7-1. Fine Particulate Matter Performance Goals and Criteria
NMB NME
Species Goal Criteria Goal Criteria
24-hr PM2.5 and Sulfate <± 10% <± 30% < 35% < 50%
24-hr Nitrate <± 10% <± 65% < 65% < 115%
24-hr OC <± 15% <± 50% < 45% < 65%
24-hr EC <± 20% <± 40% < 50% < 75%
In addition to these goals, Alpine will compare performance evaluation metrics generated using
CAMx 6.40 for each modeled species to EPA’s evaluation metrics for the same simulation using
CAMx 6.32. In cases where the VISTAS II performance metrics differ by more than 10% from
EPA’s regional haze metrics, Alpine will document the differences and provide summaries to
SESARM for discussion and resolution, as necessary.
Because PM2.5 is a mixture, current EPA PM modeling guidance (EPA, 2014e) recommends that
a meaningful performance evaluation should include an assessment of how well the model is
able to predict individual chemical components that constitute PM2.5.
Consistent with EPA’s performance evaluation of the regional haze 2028 analysis, in addition to
total PM2.5, components of PM2.5 Alpine will assess:
• Sulfate ion (SO42-)
• Nitrate ion (NO3-)
• Ammonium ion (NH4+)
• Elemental Carbon (EC)
• Organic Carbon (OC) and/or Organic Carbon Mass (OCM)
• Crustal (weighted average of the most abundant trace elements in ambient air)
• Sea salt constituents (Na and Cl)
The mapping of the CAMx species into the observed species are presented in Table 7-2.
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Table 7-2. Species Mapping from CAMx_6.40 into Observation Network
Network Observed
Species CAMx Species
IMPROVE NO3 PNO3
SO4 PSO4
NH4 PNH4
OM = 1.8*OC SOA1+SOA2+SOA3+SOA4 +SOPA+SOPB+POA
EC PEC
SOIL FPRM+FCRS
PM2.5 PSO4+PNO3+PNH4+SOA1+SOA2+SOA3+SOA4
+SOPA+SOPB+POA+PEC+FPRM+FCRS+NA+PCL
CSN PM2.5 PSO4+PNO3+PNH4+SOA1+SOA2+SOA3+SOA4
+SOPA+SOPB+POA+PEC+FPRM+FCRS+NA+PCL
NO3 PNO3
SO4 PSO4
NH4 PNH4
OM = 1.4*OC SOA1+SOA2+SOA3+SOA4 +SOPA+SOPB+POA
EC PEC
7.2.1 Diagnostic Evaluation
If the annual CAMx model base case simulations present performance challenges, it may
necessitate focused diagnostic and sensitivity testing in order for them to be resolved. If needed,
it is hopeful that these diagnostic and/or sensitivity tests can be adequately carried out within the
resources and schedule of this contract. If not, then it may be necessary to draw upon the
Optional Task 11 resources to conduct the necessary work. Where practical, diagnostic or
sensitivity analyses, if needed, could be performed on selected episodes within the annual cycle,
thereby avoiding the time-consuming task of running CAMx for the full 2011 period. Upon
identification of performance evaluation failure, Alpine will identify the types of diagnostic and
sensitivity testing methods that might be employed in diagnosing inadequate model performance
and devising appropriate methods for improving the model response. Upon discussion,
negotiation, and approval with and by SESARM and EPA of evaluation procedures to conduct,
Alpine will execute the tests, identify the issues, propose and resolution to the problem, and
apply any changes as approved.
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8.0 AREA OF INFLUENCE
Under this task, ERG will identify the 20% most impaired days for each Class I area in the
VISTAS_12 modeling domain over the 2011-2016 period based on the IMPROVE monitoring
website RHR summary of the 20% most-impaired visibility days.30 Due to the presence of large
SO2 emission reductions during this six-year period, the area of influence (AoI) analysis will be
set up to look at: 1) each year individually; 2) two separate periods of 2011-2013 and 2014-2016;
and 3) for all years combined.
The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model 31 developed by
the National Oceanic and Atmospheric Administration’s (NOAA) Air Resources Laboratory
(ARL) will be run for each of these days to identify areas most likely influencing visibility. The
HYSPLIT runs will use the NAM-12 hybrid meteorology and trajectory will be run for starting
heights of 100 meters (m), 500 m, 1,000 m, and 1,500 m. Trajectories will be run 72 hours
backwards in time at each height and location. The AoI analysis will be set up to look at: 1) each
starting height individually and 2) all starting heights combined.
Trajectories will be run with start times of 12AM (midnight of the start of the day), 6AM, 12PM,
6PM, and 12AM (midnight at the end of the day) local time. Trajectories will originate from
each of the forty (40) IMPROVE monitors in the VISTAS_12 domain (Table 8-1 and Figure
8-1). Based on analysis from NC, ERG omitted several western states, as trajectories originating
in Class I areas in those states do not pass over a SESARM state (hatched shading in Figure 8-1).
In certain instances, the trajectory origin will be the centroid of the Class I area. Class I areas
without a dedicated IMPROVE monitor will have their trajectories originate from the centroid of
the Class I area. Visibility data will be based on an appropriate IMPROVE monitor, as
previously determined by the federal Land Managers. Another example when the monitor is
remove from the Class I area. For example, the Breton Island trajectory will start from the
centroid of the Class I, as the monitor has been moved further on shore in Louisiana. There are
nine (9) such areas identified in the VISTAS 12km domain.
In instances where all years are not available at an IMPROVE monitoring site, the 20% most
impaired days from the year years available will be analyzed. For example, Shining Rock
Wilderness area does not have data for 2011, as a result the trajectories for area of influence
analysis will only cover the 2012 to 2016 period.
Three VISTAS region Class I areas do not have an IMPROVE monitor: Wolf Island, Joyce
Kilmer-Slickrock and Otter Creek. For these sites, trajectories will originate from the centroid of
the Class I area (Figure 8-2). The 20% most impaired dates will be based off a representative
IMPROVE monitor, which are listed in Table 8-2.
30 http://vista.cira.colostate.edu/Improve/rhr-summary-data/
31 Stein, A.F., Draxler, R.R, Rolph, G.D., Stunder, B.J.B., Cohen, M.D., and Ngan, F., (2015). NOAA’s HYSPLIT atmospheric
transport and dispersion modeling system, Bull. Amer. Meteor. Soc., 96, 2059-2077, http://dx.doi.org/10.1175/BAMS-D-14-
00110.1
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Table 8-1. IMPROVE Monitors in the VISTAS_12 Domain
IMPROVE Site
IMPROVE
Site Code State
FIPS
Code Latitude Longitude Start Date End Date
Sipsey Wilderness SIPS1 AL 01079 34.3433 -87.3388 03/04/1992 04/28/2017
Caney Creek CACR1 AR 05113 34.4544 -94.1429 06/24/2000 04/28/2017
Upper Buffalo Wilderness UPBU1 AR 05101 35.8258 -93.2030 12/04/1991 04/28/2017
Chassahowitzka NWR CHAS1 FL 12017 28.7484 -82.5549 03/03/1993 04/28/2017
Everglades NP EVER1 FL 12086 25.3910 -80.6806 09/03/1988 04/28/2017
St. Marks SAMA1 FL 12129 30.0926 -84.1614 08/16/2000 04/28/2017
Cohutta COHU1 GA 13213 34.7852 -84.6265 06/03/2000 04/28/2017
Okefenokee NWR OKEF1 GA 13049 30.7405 -82.1283 09/04/1991 04/28/2017
Mammoth Cave NP MACA1 KY 21061 37.1318 -86.1479 09/04/1991 04/28/2017
Breton Island BRIS1 LA 22075 30.1086 -89.7617 01/16/2008 04/28/2017
Acadia NP ACAD1 ME 23009 44.3771 -68.2610 03/02/1988 04/28/2017
Moosehorn NWR MOOS1 ME 23029 45.1259 -67.2661 12/03/1994 04/28/2017
Isle Royale NP ISLE1 MI 26083 47.4596 -88.1491 11/17/1999 04/28/2017
Seney SENE1 MI 26153 46.2889 -85.9503 11/17/1999 04/28/2017
Boundary Waters Canoe Area BOWA1 MN 27075 47.9466 -91.4955 06/01/1991 04/28/2017
Voyageurs NP #2 VOYA2 MN 27137 48.4126 -92.8286 03/02/1988 04/28/2017
Hercules-Glades HEGL1 MO 29213 36.6138 -92.9221 03/02/2001 04/28/2017
Mingo MING1 MO 29207 36.9717 -90.1432 06/03/2000 04/28/2017
Linville Gorge LIGO1 NC 37011 35.9723 -81.9331 04/01/2000 04/28/2017
Shining Rock Wilderness SHRO1 NC 37087 35.3937 -82.7744 06/01/1994 04/28/2017
Swanquarter SWAN1 NC 37095 35.4510 -76.2075 06/10/2000 04/28/2017
Great Gulf Wilderness GRGU1 NH 33007 44.3082 -71.2177 06/03/1995 04/28/2017
Brigantine NWR BRIG1 NJ 34001 39.4650 -74.4492 09/04/1991 04/28/2017
Bandelier NM BAND1 NM 35028 35.7797 -106.2664 03/02/1988 04/28/2017
Bosque del Apache BOAP1 NM 35053 33.8695 -106.8520 04/15/2000 04/28/2017
Salt Creek SACR1 NM 35005 33.4598 -104.4042 04/08/2000 04/28/2017
San Pedro Parks SAPE1 NM 35039 36.0139 -106.8447 08/16/2000 04/28/2017
Wheeler Peak WHPE1 NM 35055 36.5854 -105.4520 08/16/2000 04/28/2017
White Mountain WHIT1 NM 35027 33.4687 -105.5349 12/03/2001 04/28/2017
Wichita Mountains WIMO1 OK 40031 34.7323 -98.7130 03/02/2001 04/28/2017
Cape Romain NWR ROMA1 SC 45019 32.9410 -79.6572 09/03/1994 04/28/2017
Great Smoky Mountains NP GRSM1 TN 47009 35.6334 -83.9416 03/02/1988 04/28/2017
Big Bend NP BIBE1 TX 48043 29.3027 -103.1780 03/02/1988 04/28/2017
Guadalupe Mountains NP GUMO1 TX 48109 31.8330 -104.8094 03/02/1988 04/28/2017
James River Face Wilderness JARI1 VA 51163 37.6266 -79.5125 06/03/2000 04/28/2017
Shenandoah NP SHEN1 VA 51113 38.5229 -78.4348 03/02/1988 04/28/2017
Lye Brook Wilderness LYBR1 VT 50003 43.1482 -73.1268 09/04/1991 09/30/2012
Lye Brook Wilderness LYEB1 VT 50025 42.9561 -72.9098 01/01/2012 04/28/2017
Dolly Sods Wilderness DOSO1 WV 54093 39.1053 -79.4261 09/04/1991 04/28/2017
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Figure 8-1. IMPROVE Monitor Locations and Starting Points for HYSPLIT Trajectories
in the VISTAS 12km Domain
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Figure 8-2. IMPROVE Monitor Locations and Starting
Points for HYSPLIT Trajectories in the VISTAS States
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Table 8-2. Representative IMPROVE Monitor for Each VISTAS Class I Area
Class I Area
Representative
IMPROVE Site
IMPROVE
Site Code State
FIPS
County
Code Latitude Longitude
AL - Sipsey Wilderness Area Sipsey Wilderness SIPS1 AL 01079 34.3433 -87.3388
FL - Chassahowitzka Wilderness Area Chassahowitzka NWR CHAS1 FL 12017 28.7484 -82.5549
FL - Everglades National Park Everglades NP EVER1 FL 12086 25.391 -80.6806
FL - St. Marks Wilderness Area St. Marks SAMA1 FL 12129 30.0926 -84.1614
GA - Cohutta Wilderness Area Cohutta COHU1 GA 13213 34.7852 -84.6265
GA - Okefenokee Wilderness Area Okefenokee NWR OKEF1 GA 13049 30.7405 -82.1283
GA - Wolf Island Wilderness Area Okefenokee NWR OKEF1 GA 13049 30.7405 -82.1283
KY - Mammoth Cave National Park Mammoth Cave NP MACA1 KY 21061 37.1318 -86.1479
NC/TN - Great Smoky Mountains National Park Great Smoky Mountains NP GRSM1 TN 47009 35.6334 -83.9416
NC/TN - Joyce Kilmer-Slickrock Wilderness Great Smoky Mountains NP GRSM1 TN 47009 35.6334 -83.9416
NC - Linville Gorge Wilderness Area Linville Gorge LIGO1 NC 37011 35.9723 -81.9331
NC - Shining Rock Wilderness Area Shining Rock Wilderness SHRO1 NC 37087 35.3937 -82.7744
NC - Swanquarter Wilderness Area Swanquarter SWAN1 NC 37095 35.451 -76.2075
SC - Cape Romain Wilderness Area Cape Romain NWR ROMA1 SC 45019 32.941 -79.6572
VA - James River Face Wilderness Area James River Face Wilderness JARI1 VA 51163 37.6266 -79.5125
VA - Shenandoah National Park Shenandoah NP SHEN1 VA 51113 38.5229 -78.4348
WV - Dolly Sods Wilderness Area Dolly Sods Wilderness DOSO1 WV 54093 39.1053 -79.4261
WV - Otter Creek Wilderness Area Dolly Sods Wilderness DOSO1 WV 54093 39.1053 -79.4261
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Trajectories will be run utilizing the SplitR package (https://github.com/rich-iannone/SplitR),
which allows the control of HYSPLIT through the R statistical software. This allows for
automation of the HYSPLIT runs for each location, while still generating the GIS shapefiles and
separate files of the endpoint for further use in R.
The back trajectories for the 20% most impaired days will then be used to develop residency
time (RT) plots via the openair 32 package for R. The RT plots define the geographic areas with
the highest probability of influencing the monitor on the 20% most impaired visibility days.
The RT is calculated as the number of trajectory hours that pass through each grid cell. This can
be presented as a percentage of the total number of trajectory hours. The grid used would align
with the photochemical modeling 12km grid for consistency with emission analysis. For further
analysis, R allows the residence time plots to be split by time increments (i.e., year, season).
Images of the RT plots will be generated for QA and review purposes. Images will at least cover
the VISTAS 12-km domain and include outlines of states and counties.
The trajectory data will also be weighted by ammonium sulfate and ammonium nitrate and used
to produce separate sulfate and nitrate extinction weighted residency time (EWRT) plots. This
allows separate analysis for sulfate and nitrate that is weighted toward the days influenced most
by those constituents and not days most influenced by other constituents, like organic carbon.
In this project, the Concentration Weighted Trajectory (CWT)33 approach will be used to develop
the EWRT, substituting the extinction value for the concentration. The extinction attributable to
each pollutant is paired with the trajectory for that day. R then calculates the mean weighted
extinction of the pollutant species for each grid cell. The mean weighted extinction is calculated
by:
𝑀𝑀�𝑣𝑣𝑖𝑖= 𝑀𝑀𝐸𝐸𝑅𝑅𝐸𝐸 = 1∑𝜏𝜏𝑣𝑣𝑖𝑖𝑖𝑖𝑁𝑁𝑖𝑖=1 �(𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑖𝑖)𝑁𝑁
𝑖𝑖=1 𝜏𝜏𝑣𝑣𝑖𝑖𝑖𝑖
where i and j are the indices of grid, k the index of trajectory, N the total number of trajectories
used in analysis, bextk is the 24-hour extinction attributed to the pollutant measured upon arrival
of trajectory k, and τijk the number of trajectory hours that pass through each grid cell (i, j)
(where “i” is the row and “j” is the column).34 The higher the value of the EWRT (𝑀𝑀̅𝑖𝑖𝑖𝑖), the more
likely that the air parcels passing over cell (i, j) would cause higher extinction at the receptor site
for that light extinction species. Since this method uses the extinction value for weighting,
trajectories passing over large sources are more discernible from those passing over moderate
sources. A point filter can be used to eliminate grid cell with few trajectory hours from the
32 Carslaw DC and Ropkins K (2012). “openair — An R package for air quality data analysis.” Environmental Modelling &
Software, 27–28(0), pp. 52–61. ISSN 1364-8152, doi: 10.1016/j.envsoft.2011.09.008.
33 Hsu, Y.-K., T. M. Holsen and P. K. Hopke (2003). “Comparison of hybrid receptor models to locate PCB sources in
Chicago”. In: Atmospheric Environment 37.4, pp. 545–562. DOI: 10.1016/S1352-2310(02)00886-5
34 Carslaw, D.C. (2015). The openair manual — open-source tools for analyzing air pollution data. Manual for Version 1.1-4,
King’s College London. http://www.openair-project.org/PDF/OpenAir_Manual.pdf
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analysis. As this distinction can help refine control strategy development, using the CWT method
to create the EWRT is ERG’s recommendation for the analysis.
The EWRT results can be normalized by the domain total to present the results as a percentage in
images. Images of the extinction weighted RT plots will be generated for QA and review
purposes. Images will at least cover the VISTAS 12-km domain and include outlines of states
and counties. An example calculation is provided in Figure 8-3, which has been simplified to
only four trajectories. In this example, two trajectories pass through the cell (1,2). The first of
these trajectories (yellow) has an extinction value (𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑖𝑖) of 50 Mm-1 associated with it. The
four yellow dots in the cell denote that four hours of the back trajectory are spent in the cell. This
yields “𝜏𝜏1,2,𝑦𝑦𝑒𝑒𝑦𝑦𝑦𝑦𝑦𝑦𝑦𝑦” equal to 4 hours. Multiplying by the extinction (𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑖𝑖) for the cell yields a
trajectory weight of 200 Mm-1hrs. This is added to the weight of the second (purple) trajectory
for a total extinction weight of 450 Mm-1hrs. This is then divided by the total number of
trajectory hours in the analysis (18 hours) to yield the final EWRT for the cell of 25 Mm-1. The
same calculation is done for cell (2,1). While the cells have the same number of trajectories and
endpoints, the weight given to cell (2,1) is higher due to the higher extinctions associated with
the trajectories.
The next phase of the analysis will combine the EWRT values with the distance weighted
gridded emission data to determine the sources most likely contributing to the elevated extinction
levels. Distances (d) for the weighting, calculated using ArcGIS, will be calculated from the
location of the point source to the trajectory origin in kilometers. The weighted emission file is
comprised of the EGU and non-EGU point source emissions value for each grid cell (Q, in tons
per year) divided by the distance (d, in kilometres) to the trajectory origin; that is the final value
is (Q/d). Each of these grid cell values is multiplied by its respective sulfate or nitrate EWRT
plot values (i.e., EWRT *(Q/d)). A simplified example calculation for a single point source per
cell is provided in Figure 8-4. Continuing with weights calculated in Figure 8-3, point sources in
cell (1,2) emit 100 tons per year (Q=100 tpy), with the centroid 12km away from the trajectory
origin. This yields a “Q/d” of 8.33 tpy/km for the source. This “Q/d” term is multiplied by the
EWRT previously calculated at 25 Mm-1 to yield a source weighted EWRT value that indicates
the potential importance of the sources in this cell to impaired visibility days in the Class I area.
Alternately, the EWRT*(Q/d) can be calculated for each source in a cell and totalled for a grid
cell total. Similar to the EWRT plots, these contribution plots can be normalized by the domain
total to present them as a percentage in plots. Images of the results will be mapped over the
VISTAS 12-km modeling domain, with state and county boundaries for review and QA
purposes.
These gridded results will then be linked with the 2011 and 2028 point source inventories to
calculate the emission contribution from each source. ArcGIS will be used to spatially join the
gridded information with shapefiles the point source information. This will create a dataset that
combines the point source metadata facility identifying information (i.e., Facility ID, Facility
Name, State, County, Federal Information Processing Standard (FIPS), North American Industry
Classification System (NAICS), and industry description), and the gridded information (i.e., SO2
and NO2 emissions, d, Q/d, EWRT, EWRT *(Q/d)). The Q/d values will be calculated by
dividing facility-wide emissions (tons per year) by distance (km) to the Class I area. In the
alternate strategy proposed above, this step would be completed first, then totalled for
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visualization. Additional information can be added as deemed necessary in making control
strategy decisions. The information from these spatial files can then be exported to separate
Excel spreadsheets for each Class I area in the VISTAS_12 domain for further review by the
states.
Figure 8-3. Example EWRT Calculations
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Figure 8-4. Example (Q/d)*EWRT Calculations
Similar analysis will be conducted to rank SO2 and NO2 emissions contributions for onroad,
nonroad, fires, and area source sectors from each county. The process will be similar to the
process for point sources previously described, except calculations of RT and EWRT will be
done to counties as opposed to grids. ERG will determine if the trajectories can be weighted
further for the time spent in the county. The length of the trajectory within the county would be
used as a proxy for time, so that trajectories that only cross a small corner of the county are not
weight as much as trajectories passing through the center of the county. This will be done in GIS
using the same calculation method as in R (i.e., CWT). The calculation of d would then be from
the centroid of the county to the trajectory origin, in kilometers. Similar to point sources, the
final spatial join would be to the county level EWRT and a shapefile of the source information at
the county level, for each sector. All county and emissions source identifying information will be
provided along with inventory emissions, distance, Q/d and Q/d2 values, EWRT, EWRT*(Q/d),
fraction and sum contributions, and any other information deemed necessary in making control
strategy decisions for each source.
All images, shapefiles, and spreadsheets will be uploaded to the files sharing platform, as
designed in Task 10, in separate folders for each Class I area or IMPROVE monitor in the
VISTAS_12 domain. Each analysis element (e.g., RT plots, summary spreadsheets) will be
contained in separate subfolders for ease of navigation. SESARM will be notified when the files
are available and ready for use. A technical memorandum/interim report describing the area of
influence calculations, and the results, will be prepared for SESARM and other stakeholders for
use in their implementation plans.
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9.0 FUTURE YEAR MODELING
This chapter discusses the future year modeling using the annual modeling databases and how
these results will be used to project 2009-2013 IMPROVE visibility data to 2028 following the
approach used in EPA’s regional haze modeling guidance (EPA, 2014e).
9.1 Regional Haze Rule Requirements
As required by the RHR, RPGs must provide for an improvement in visibility for the 20 percent
most anthropogenically impaired days relative to baseline visibility conditions and ensure no
degradation in visibility for the 20 percent clearest days relative to baseline visibility conditions.
The baseline for each Class I area is the average visibility (in dvs) for the years 2000 through
2004. The visibility conditions in these years are the benchmark for the “provide for an
improvement” and “no degradation” requirements. In addition, states are required to determine
the rate of improvement in visibility needed to reach natural conditions by 2064 for the 20
percent most anthropogenically impaired days. A line drawn between the end of the 2000-2004
baseline period and 2064 (dv/year) shows a uniform rate of progress (URP) between these two
points. This “glidepath” is the amount of visibility improvement needed in each implementation
period, starting from the baseline period, to stay on a linear path towards visibility improvement
to natural conditions by 2064. The glidepath represents a linear or uniform rate of progress. This
is a framework for consideration but there is no requirement to be on or below the glidepath.
The RHR requires states to submit an implementation plan that evaluates reasonable progress for
implementation periods in approximately ten-year increments. The next regional haze SIP is due
in 2021, for the implementation period which ends in 2028 (period of 2019-2028).
Therefore, modeling is being conducted to project visibility to 2028 using a 2028 emissions
inventory with “on-the-books” controls. The EPA Software for Model Attainment Test-
Community Edition (SMAT-CE) tool 35 will be used to calculate 2028 dv values on the 20% most
impaired and 20% clearest days at each Class I Area (IMPROVE site). SMAT-CE is an EPA
software tool which implements the procedures in the modeling guidance to project visibility to a
future year.
9.2 Future Year to be Simulated
As discussed in Section 1, to support the preliminary 2028 regional haze modeling requested by
SESARM, Alpine will conduct air quality modeling to project particulate matter concentrations
at individual monitoring sites to 2028 and to estimate changes in regional haze as a result of
those concentrations.
9.3 Future Year Baseline Air Quality Simulations
The 2028 future year base case CAMx simulation will be conducted, and particulate matter
concentration calculations made following the procedures in Section 5 and that are consistent
with EPA’s latest regional haze modeling analysis (EPA, 2017b).
35 https://www.epa.gov/scram/photochemical-modeling-tools
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9.4 Calculation of 2028 Visibility
The visibility projections will follow the procedures in EPA’s modeling guidance (EPA, 2014e).
Based on the recommendation in the modeling guidance, the observed base period visibility data
will be linked to the base modeling year. This is the 5-year ambient data base period centered
about the base modeling year. In this case, for a base modeling year of 2011, the ambient
IMPROVE data will be from the 2009-2013 period.
The visibility calculations will use the “revised” IMPROVE equation (Hand, 2006); (Pitchford,
2007), which has replaced the original IMPROVE equation and has been used in most regional
haze SIPs over the last 10 years. The IMPROVE equation (or algorithm), which uses PM species
concentrations and relative humidity data to calculate visibility impairment, or bext, in units of
inverse megameters (Mm-1), is presented below:
b_ext ≈2.2 ×f_s (RH) × [Small Sulfate]+4.8 ×f_L (RH) × [Large Sulfate]+ 2.4 ×f_s (RH) ×
[Small Nitrate]+5.1 ×f_L (RH) × [Large Nitrate]+2.8 × [Small Organic Mass]+ 6.1 ×
[Large Organic Mass]+ 10 × [Elemental Carbon]+ 1 × [Fine Soil]+1.7×f_SS (RH) ×
[Sea Salt]+0.6 × [Coarse Mass] + Rayleigh Scattering (Site Specific) + 0.33 × [NO_2
(ppb)]
The total sulfate, nitrate, and organic carbon compound concentrations are each split into two
fractions, representing small and large size distributions of those components. Site-specific
Rayleigh scattering is calculated based on the elevation and annual average temperature of each
IMPROVE monitoring site.
The 2028 future year visibility on the 20% most impaired days and 20% clearest days at each
Class I area will be estimated using the observed IMPROVE data (2009-2013) and the relative
percent modeled change in PM species between 2011 and 2028. The process is described in the
following six steps.
1. For each Class I area (IMPROVE site), estimate anthropogenic impairment 36 on each day
using observed speciated PM2.5 data plus PM10 data (and other information) for each of
the 5 years comprising the base period (2009-2013 in this case) and rank the days on this
indicator. This ranking will determine the 20 percent most anthropogenically impaired
days. For each Class I area, also rank observed visibility (in dvs) on each day using
observed speciated PM2.5 data plus PM10 data for each of the 5 years comprising the base
period. This ranking will determine the 20 percent clearest days.
2. For each of the 5 years comprising the base period, calculate the mean dvs for the
20 percent most anthropogenically impaired days and 20 percent clearest days. For each
Class I area, calculate the 5 year mean dvs for most impaired and clearest days from the
5 year-specific values.
3. Use an air quality model to simulate air quality with base period (2011) emissions and
future year (2028) emissions. Use the resulting information to develop site-specific
relative response factors (RRFs) for each component of PM identified in the “revised”
36 http://vista.cira.colostate.edu/Improve/rhr-summary-data/
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IMPROVE equation. The RRFs are an average percent change in species concentrations
based on the measured 20% most impaired and 20% clearest days from 2011 (the
calendar days identified from the IMPROVE data above are matched to the same
modeled days).
4. Multiply the species-specific RRFs by the measured daily species concentration data
during the 2009-2013 base period (for each day in the measured 20% most impaired day
set and each day in the 20% clearest day set), for each site. This results in daily future
year 2028 PM species concentration data.
5. Using the results in Step 4 and the IMPROVE algorithm, calculate the future daily
extinction values for the previously identified 20 percent most impaired days and 20
percent clearest days in each of the five base years.
6. Calculate daily dv values (from total daily extinction) and then compute the future year
(2028) average mean dvs for the 20 percent most impaired days and 20 percent clearest
days for each year. Average the five years together to get the final future mean dv values
for the 20 percent most impaired days and 20 percent clearest days.
The SMAT-CE tool will be used to generate individual year and 5-year average base year and
future year dv values on the 20% most impaired days and 20% clearest days. Additional SMAT
output variables include the results of intermediate calculations such as species-specific
extinction values (both base and future year) and species specific RRFs (on the 20% most
impaired and clearest days).
Table 9-1 details the settings to be used for the SMAT runs to generate the 2028 future year dv
projections:
Table 9-1. SMAT-CE Settings for 2028 Visibility Calculations
SMAT-CE Option Setting or File Used
IMPROVE algorithm Use new version
Grid cells at monitor or Class I area
centroid?
Use grid cells at monitor
IMPROVE data file ClassIareas_NEWIMPROVEALG_2000to2015_2017apri
l27_IMPAIRMENT.csv
Temporal adjustment at monitor 3 x 3
Start monitor year 2009
End monitor year 2013
Base Model year 2011
Minimum years required for a valid
monitor
3
In order for Alpine to conduct the source apportionment runs, the CAMx 2011 and 2028 model
output will be post-processed using a “species definition file” that cross references raw CAMx
output species names with PM species needed for SMAT. The results of the post-processing are
24-hour average PM species with the “combine file” output names. These are matched to the
SMAT species as shown in Table 10-1.
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Table 9-2. Matching of CAMx_6.40 Raw Output Species to SMAT Input Variables
SMAT Species
“Combine File”
Output Name Raw CAMx 6.40 Species
Sulfate PM25_SO4 PSO4
Nitrate PM25_NO3 PNO3
Ammonium1 PM25_NH4 PNH4
Organic Matter PM25_OM POA+SOA1+SOA2+SOPA+SOA3+SOA4+ SOPB
Elemental carbon PM25_EC PEC
Crustal CRUSTAL FCRS+FPRM
Coarse PM PMC_TOT CCRS+CPRM
PM2.52 PM25_SMAT CRUSTAL+PSO4+PNO3+PNH4+PEC+NA+PCL+
SOA1+SOA2+SOA3+SOA4 +SOPA+SOPB+POA
1 Modeled ammonium concentrations are not used in the post-processing of the 2028 visibility values because the
IMPROVE network does not measure ammonium and there is not an ammonium term in the IMPROVE visibility
equation.
2 Note that total PM2.5 concentration data is needed as a SMAT input variable, but it is not used in the visibility
calculations for regional haze. Visibility calculations only use the species-specific model outputs.
9.5 Comparison to Regional Haze “Glidepath”
The future year 2028 dv projections will be compared to the unadjusted visibility “glidepath” at
each Class I area. The unadjusted “glidepath” represents the amount of visibility improvement
needed in each implementation period, starting from the baseline 2000-2004 period, to stay on a
linear path to natural visibility conditions by 2064. Visibility on the 20% most impaired days is
compared to the relevant value of the glidepath, in this case for a future year of 2028. Since the
glidepath is a linear path between 2004 and 2064, a glidepath value (in dvs) can be calculated for
any future year, using a simple equation. The following formula will be used to calculate the
2028 glidepath value:
Glidepath2028= Baseline average dv – (((Baseline average dv – Natural conditions)/60)*24)
Where,
Baseline average dv = average observed dv value on the 20% most impaired days for
2000-2004
Natural conditions= Natural conditions on the 20% most impaired days at the Class I
area (in dv)
Once calculated, the 2028 future year projected dv values can be compared to the unadjusted
glidepath for 2028 to determine if the Class I area is projected to be above, below, or on the
glidepath. While the RHR requires future year projected visibility impairment be compared to
the glidepath, it does not require the RPGs be on or below the glidepath. However, the rule has
different requirements depending on whether the projected value (RPG) is above or below the
glidepath.
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10.0 PSAT SOURCE APPORTIONMENT
In order to gain a better understanding of the source contributions to modeled visibility, Alpine
will use CAMx Particulate Source Apportionment Technology (PSAT) modeling. PSAT uses
multiple tracer families to track the fate of both primary and secondary PM (Yarwood et al.,
2004). PSAT is designed to apportion the following classes of CAMx PM species:
• Sulfate (PSO4)
• Particulate nitrate (PNO3)
• Ammonium (PNH4)
• Secondary organic aerosol (SOA)
• Primary PM (PEC, POA, FCRS, FPRM, CCRS, and CPRM)
• Particulate mercury (HGP)
PSAT allows emissions to be tracked (tagged) by various combinations of sectors and
geographic areas (e.g., by state or facility). For this application, 2028 emissions will be tagged
(“tag”) using SESARM-identified combinations of region, facilities, and/or source category.
Each combination accounts for a single “tag” with SESARM planning to identify up to 250
individual tagged combinations. Each of these emissions combinations will be processed
separately through SMOKE and tracked in PSAT as individual source tags. Receptors, identified
as all the Class I areas in the VISTAS_12 modeling domain, will be used to analyze the results
and impacts of each tagged combination.
For this application, only sulfate and nitrate will be tracked using PSAT. Tracking of other
contributions may also be of use but is not requested in this analysis. In the PSAT post
processing the data will be converted from the UTC based modeling data into 24-hour average
grid cell local standard time using the HR2DAY 37 utility program. The HR2DAY program
matches each grid cell in the model to a time zone and performs the 24-hour average on the time
zone adjusted hourly data. This is the same program that EPA uses in their national modeling.
In order for Alpine to conduct the source apportionment runs, the CAMx 2011 and 2028 model
output will be post-processed using a “species definition file” that cross references raw CAMx
output species names with PM species needed for SMAT. The results of the post-processing are
24-hour average PM species with the “combine file” output names. These are matched to the
SMAT species as shown in Table 10-1.
Table 10-1. Matching of CAMx Raw Output Species to SMAT Input Variables
SMAT Species Raw CAMx 6.40 Species
Sulfate (SO4) PSO4
Nitrate (NO3) PNO3
Ammonium (NH4)1 PNH4
Organic Matter (OM) POA+SOA1+SOA2 +SOA3+SOA4+SOPA+SOPB
Elemental carbon (EC) PEC
Crustal (CRUSTAL) FPRM+FCRS
37 https://www.airqualitymodeling.org/index.php/CMAQv5.1_Tools_and_Utilities#HR2DAY_utility_program
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Table 10-1. Matching of CAMx Raw Output Species to SMAT Input Variables
SMAT Species Raw CAMx 6.40 Species
Coarse PM (CM) CPRM+CCRS
PM2.5 (PM25)2 PSO4+PNO3+PNH4+POA+PEC+FCRS+FPRM+SOA1+SOA2+SOA3+
SOA4+SOA4+SOPA+SOPB+NA+PCL
1 Modeled ammonium concentrations are not used in the post-processing of the 2028 visibility values because the
IMPROVE network does not measure ammonium and there is not an ammonium term in the IMPROVE visibility
equation.
2 Note that total PM2.5 concentration data is needed as a SMAT input variable, but it is not used in the visibility
calculations for regional haze. Visibility calculations only use the species-specific model outputs.
10.1 Process for Creating PSAT Contributions for Class I Areas
The CAMx hourly concentration data will be post-processed to create SMAT input files. This
will involve processing both the 2028 “full model” and the specific source apportionment
outputs. The “full model” results are the total PM species concentrations (e.g. sulfate, nitrate)
and are identical to the total species concentrations from the non-source apportionment model
run for 2028 (e.g., future year base case). The source apportionment outputs contain the sulfate
and/or nitrate contributions for each tagged source.
The PSAT source apportionment tracking uses slightly different variables names for the source
apportionment variables. Table 10-2 below shows the SMAT species definition matching to be
used for the 2028 full model and 2028 source apportionment results in the VISTAS II analysis.
Table 10-2. Matching of “Bulk Raw Species”, PSAT Output Species, and
SMAT Input Variables
SMAT Species 2028 Full Model Species 2028 PSAT Tag Raw Species
Sulfate PSO4 PS4
Nitrate PNO3 PN3
Ammonium PNH4 PN4
This analysis will use a comparable method that was documented by EPA in the regional haze
modeling for 2028. Slight differences do occur as in this study we are looking at the SMAT-CE
generated visibility/extinction deltas whereas EPA’s approach was designed for a different
purpose than just to estimate emissions sector contributions to 2028 particulate matter
concentrations and visibility. As a reminder, SESARM is only looking for individual facility or
sector contributions to visibility impairment based on defined sulfate and nitrate tags and not
looking to establish a full list of species-based contribution metrics.
The following approach will be used in preparing the SMAT input files, running the SMAT
software, and analysing the results:
1. Regional haze SMAT will be run for the 2028 future case using “standard” 2011 and
2028 SMAT input files. In this SMAT run, the advanced option “Create forecast
IMPROVE visibility file” will be invoked to create an output file with future year (2028)
daily species extinction values at each IMPROVE monitor for each of the 20% best and
most impaired days (based on 2011 ambient data). These are the extinction values that
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are added and averaged to get the 2028 base case projected deciview values for each site.
SMAT generates a new output file called “scenario_name Forecast IMPROVE Daily
Data.csv” that was re-used to calculate the sector tag fractions.
2. Alpine will then create future year, tag-specific SMAT input files by subtracting the 2028
hourly tags from the hourly full model concentration files. This simple arithmetic will be
implemented using standard IOAPI utility programs and generating files similar to EPA’s
source category-based tagged SMAT input files. Once the hourly files are created, the
same processing stream as was used in Step 1 will be used create the tagged SMAT input
files from the hourly model concentration files.
3. SMAT will then run again for each sector tag, using the “advanced options” accessing the
“Forecast IMPROVE Daily Data” file (created as an output file from step 1 above) as the
“advanced option” input file, the 2028 base case SMAT input file is used as the “Baseline
file”, and each 2028 sector tag SMAT input file will be used as the “Forecast file”.
4. The total extinction (on the 20% most impaired days) for each tag will be calculated from
the SMAT bulk output file and each of the tag output files. The visibility impacts of each
tag will be computed by subtracting the SMAT output absent the tag (created in Step 3)
from the full model SMAT output file (created in Step 1).
An example calculation for Cohutta using EPA’s 2028 draft regional haze modeling SMAT input
and generated output files is provided in Table 10-3 below. In this calculation, we use the 2011
base year and 2028 base case simulation compared to the 2011 base year and Sector 9 (no EGUs)
simulation. Visibility (in dv) and bext are provided as examples; numbers are rounded in this
example and may not sum due to rounding.
Table 10-3. Tagged Contribution Calculation Example
SMAT
Calculated
Value
2028 Base Case
2028 Sector 9
(Absent EGUs)
Delta (Base – Sector 9)
Tag Impact
Best 20%
Days
Most
Impaired
20% Days
Best 20%
Days
Most
Impaired
20% Days
Best 20%
Days
Most
Impaired
20% Days
Visibility (dv_f) 9.11 17.69 8.07 16.07 1.04 1.62
Bext_f (Mm-1) 25.41 59.75 22.79 50.9 2.62 8.84
In summary, since SMAT directly provides visibility metrics for the 20% most impaired and
20% clearest days, our proposed application is to subtract the visibility results of the tagged run
(deciviews absent the tag) from the 2028 base case run to determine to contribution of each tag
to the total base case visibility value.
Alpine will continue to review this method with SESARM and EPA and should a change be
warranted in the calculation steps, we will change the calculation to meet the needs of SESARM
prior to running the contribution steps.
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Finally, using data from the resulting calculations, Alpine will create the day-by-day stacked bar
charts of total and speciated component bext (ammonium sulfate, ammonium nitrate, OC, EC,
crustals, CM) for the 20% most impaired and 20% clearest days per site for each IMPROVE
monitor in the VISTAS_12 modeling domain and as directed by SESARM will also modify the
similar 2011 site-by-site charts to include 2028 modeled data.
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11.0 MODELING DOCUMENTATION AND DATA ARCHIVE
EPA recommends that certain types of documentation be provided along with a photochemical
modeling attainment demonstration. ERG and Alpine Geophysics are committed to supplying the
material needed to ensure that the technical support for this analysis is understood by all
stakeholders, EPA, and SESARM.
Alpine plans to archive all documentation and modeling input/output files generated as part of
the VISTAS II modeling analysis and will provide a copy to SESARM for permanent archival,
additional internal use, and public distribution. Key participants in this modeling effort will be
given data access to the archived modeling information.
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