i 

# Commonwealth of Pennsylvania Department of Environmental Protection

Final Air-Quality Modeling Protocol

For the Annual PM 2.5 

## NAAQS

Philadelphia-Wilmington, PA-NJ-DE

Annual PM 2.5 

## Nonattainment Area

October 2007



## Bureau of Air Quality Pennsylvania Department of Environmental Protection

P.O. Box 8468 Harrisburg, PA 17105-8468

717-787-9495

www.dep.state.pa.usii This page left intentionally blankiii Table of Contents

1.0 Overview of Philadelphia-Wilmington Annual PM 2.5 Nonattainment Modeling

Demonstration.................................................................................................................. ... 1 1.1 Background and Objectives ..................................................................................... 1 1.2 Philadelphia-Wilmington Annual PM 2.5 Nonattainment Area ................................ 2 1.3 Philadelphia-Wilmington Data Analysis Summary................................................. 4

1.4 Technical Committees ............................................................................................. 5 1.5 Participating Organizations...................................................................................... 6 1.6 Schedule for Completion ......................................................................................... 6 2.0 Model and Modeling Inputs......................................................................................... 6 2.1 Selection of Air Quality, Meteorological and Other Model Inputs ......................... 6 2.2 Modeling Domain .................................................................................................... 7

2.3 Horizontal and Vertical Grid Resolution ................................................................. 7 2.4 Model Initial and Boundary Conditions .................................................................. 8 2.5 Near-Scale Modeling ............................................................................................... 8 2.6 Episode Selection..................................................................................................... 9 2.7 Meteorological Model.............................................................................................. 9 2.8 Emission Inputs...................................................................................................... 10

2.9 Area Examined in the Attainment Demonstration................................................. 10 2.10 Quality Assurance................................................................................................ 11

3.0 Model Performance Evaluation ................................................................................. 12

3.1 Ambient Data Base ................................................................................................ 12

3.2 Evaluation Procedures ........................................................................................... 13 4.0 Attainment Demonstration and other Supplemental Analyses .................................. 13

4.1 Model Attainment Test .......................................................................................... 13 4.2 Unmonitored Area Analysis .................................................................................. 14 4.3 Additional Analyses............................................................................................... 15 5.0 Procedural Requirements........................................................................................... 15 5.1 Reporting................................................................................................................ 1 6 5.2 Data Archive and Delivery of Modeling Files....................................................... 16

6.0 References................................................................................................................ .. 16

Table of Figures

Figure 1-1 Philadelphi a-Wilmington Annual PM 2.5 Nonattainment Area......................... 3 Figure 1-2 Annual Design Values: Philadelphia-Wilmington annual PM 2.5 Nonattainment Area.................................................................................................... 4 Figure 2-1 OTC Mode ling Study Domain......................................................................... 7

Table of Tables

Table 1-1 Historic Design Values : Philadelphia-Wilmington annual PM 2.5 Nonattainment Area.................................................................................................... 4 Table 1-2 Summary of PM 2.5 WOE Guidelines (from the U.S. EPA Guidance) ............ 151 1.0 Overview of Philadelphia-Wilmington Annual PM 2.5 Nonattainment Modeling

Demonstration

This section provides background information and describes the basic structure to the

PM 2.5 demonstration that the Pennsylvania Depa rtment of Environm ental Protection (PA DEP) will undertake. Final modeling guidelines for PM 2.5 were issued on April 16, 2007 (posted on the U.S. EPA’s Support Center fo r Regulatory Air Modes, SCRAM). This modeling protocol follows the structure out lined in section 12.2 of the U.S. EPA’s

Guidance on the Use of Models and Other Anal yses for Demonstrating Attainment of Air Quality Goals for Ozone, PM 2.5 , and Regional Haze

.

1.1 Background and Objectives

Background information on PM 2.5 included in this section was taken from the U.S. EPA’s website (www.epa.gov/pmdesignations/). This includes basic information on PM 2.5 components and their health affects.

Particle pollution is a mixture of microscopi c solids and liquid droplets suspended in air. This pollution, also known as particulate matte r, is made up of a number of components, including acids (such as nitrat es and sulfates), organic chemicals, metals, soil or dust particles, and allergens (such as fr agments of pollen or mold spores).

Fine particle pollution or PM 2.5 describes particulate matter th at is less than or equal to

2.5 μ m in diameter, approximately 1/30th the diameter of a human hair.

Fine particle pollution can be emitted directly or formed secondarily in the atmosphere. Examples of some of the primary forms of secondary pollutants include:

Sulfates: These are formed from sulfur dioxide emissions from power plants and

industrial facilities.

Nitrates: These are formed from emissi ons of nitrogen oxides from power plants, automobiles, and other combustion sources.

The chemical composition of particles depends on location, time of year, and weather.

Health studies have shown a significant asso ciation between exposur e to fine particles and premature death from heart or lung diseas e. Fine particles can aggravate heart and lung diseases and have been linked to effect s such as: cardiovascular symptoms; cardiac arrhythmias; heart attacks; re spiratory symptoms; asthma attacks; and bronchitis. These effects can result in increased hospital admissi ons, emergency room visits, absences from school or work, and restricted activity days. I ndividuals that may be particularly sensitive to fine particle exposure include people w ith heart or lung disease, older adults, and

children.2 The U.S. EPA issued the fine particle st andards in 1997 after ev aluating hundreds of health studies and conducting an extensive peer review process. The annual standard is a level of 15.0 micrograms per cubic meter ( μ g/m 3 ), based on the 3-year average of annual

mean PM 2.5 concentrations. The U.S. EPA establ ished a twenty-four hour standard of 65 micrograms per cubic meter ( μ g/m 3 ), determined by the 3-year average of the annual 98th percentile concentrations. In 2006 the U. S. EPA lowered the twenty-four hour PM 2.5 standard to 35 μ g/m 3 . Because the nonattainment desi gnations for new twenty-four hour

PM 2.5 standard are not yet in place, the Commonwealth’s PM 2.5 modeling analyses will instead use the1997 twenty-four hour standard (65 μ g/m 3 ). Final PM 2.5 SIPs are due in April of 2008.

In April 2003, the U.S. EPA issued a memo randum outlining the schedule for designating

areas under the PM 2.5 standard and related guidance on nine factors to consider in identifying nonattainment areas. The Clean Ai r Act provides for states and tribes to submit designation recommendations to the U.S. EPA, and it requires the U.S. EPA to provide time for consultation in cases where the Administrator plans to promulgate a designation that modifies the state or trib al recommendation. On December 17, 2004 The U.S. EPA published its air quali ty designations and classifications for the fine particles (PM 2.5 ) national ambient air qual ity standards (NAAQS). These designations became effective on April 5, 2005.

The objective of this protocol is to outline th e methods and procedures that will be used to support the modeling demonstration. The Depa rtment will take the lead in developing emission control strategies to demonstr ate the Philadelphia-Wilmington annual PM 2.5 nonattainment area will reach attainment by the designated attainment date, April 2010 (five years from the final designations).

1.2 Philadelphia-Wilmington Annual PM 2.5 Nonattainment Area

The Philadelphia-Wilmington annual PM 2.5 nonattainment area is a three-state nonattainment area including the five-count y Philadelphia area (Pennsylvania), one county in Delaware and three counties in the state of New Jersey. Figure 1-1 graphically depicts all of the annual PM 2.5 nonattainment areas within Pennsylvania.

The Philadelphia-Wilmington nonattainment ar ea currently violates the U.S. EPA’s

health-based annual PM 2.5 standard (15.0 μ g/m 3 ). Philadelphia-Wilmington annual PM 2.5 nonattainment area’s 2006 annual design value is 15.2 μ g/m 3 and its twenty-four hour design value is 36.5 μ g/m 3 . This is below the 1997 twenty-four hour PM 2.5 standard (65

μ g/m 3 ). Philadelphia-Wilmington annual PM 2.5 nonattainment area will need to

demonstrate that it will attain of the annual PM 2.5 standard by no later than five years from the final designation date of April 5, 2005 (April, 2010).3 Figure 1-1 Philadelphia-Wilmington Annual PM 2.5 Nonattainment Area

There are eight (8) monitoring sites current ly operating in the Philadelphia-Wilmington

annual PM 2.5 nonattainment area. The Departme nt operates several types of PM 2.5 monitors within the Philadelphia-Wilmington annual PM 2.5 nonattainment area; four (4) Federal Reference Method (FRM) samplers, two (2) PM 2.5 speciation monitors and two (2) continuous PM 2.5 monitor. FRM sampling began in January of 1999 and speciated sampling began in April of 2002. Sample fr equencies for the Philadelphia-Wilmington FRM monitors range from once per day (1/1 ) to once every three days (1/3) and once every six days (1/6) for the speciated samplers. One of the continuous PM 2.5 monitors has been operational since October 2003 while another be came operational in May of

2006. Measurements from the continuous mon itor are generally used for air-quality forecasting purposes and cannot be used to determine attainment status.4 1.3 Philadelphia-Wilmington Data Analysis Summary

Table 1-1 lists the historic PM 2.5 concentrations in the Ph iladelphia-Wilmington annual

PM 2.5 nonattainment area. Historic FRM da ta indicate the Philadelphia-Wilmington

annual PM 2.5 nonattainment area has consistently exceeded the health-based annual PM 2.5 standard since the Department began sampling (see Figure 1-2).

Table 1-1 Historic Design Values: Philadelphia-Wilmington annual PM 2.5 Nonattainment Area

Year 98th 24-Hour 24-Hour Design Value Annual Annual Design Value

2000 15.99

2001 39.5 15.86

2002 31.9 14.73 15.5

2003 37.8 36 15.29 15.3

2004 30.5 33 15.02 15.0

2005 37.0 35 16.51 15.6

2006 36.7 35 13.99 15.2

Annual standard: 15.0 μ g/m 3 Twenty-four hour standard 65 μ g/m 3

Figure 1-2 Annual Design Values: Philadelphia-Wilmington annual PM 2.5 Nonattainment Area



### Philadelphia-Wilmington Nonattainment Area

Annual PM 2.5 

### Concentrations

12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00

2000 2001 2002 2003 2004 2005 2006Concentrations (ug/m3)

Annual

Annual Design Value

Annual Standard5 The Department has reviewed FRM, speciated and continuous PM 2.5 data within the Philadelphia-Wilmington annual PM 2.5 nonattainment area. More detailed analyses are included in Appendices A, B a nd C. Results from these appendices form the basis of our general conceptual model. As more analyses are completed in the future, our conceptual model may need to be updated.

A short list of findings is set forth below:

• The majority of FRM monitors within the Philadelphia-Wilmington annual

PM 2.5 nonattainment area appear to have significant trends (see Appendix E). The bulk of these trends appear to be downward. Decreases in annual PM 2.5 concentrations may be due to emission reductions in the mobile-source sector since many of the trend monitors are located near major highways.

• The major components in the speciated data are sulfates, organic carbon, nitrates and ammonium. Component percentages for speciated monitors within the Philadelphia-Wilmington annual PM 2.5 nonattainment area are similar to results from nearby speciated monitors.

• Results from Norristown’s continuous TEOM monitor are very similar to the corresponding FRM values i ndicating results from the continuous monitor are a good reflection of actual concentrations on days when an FRM sample is not

collected.

• Additional observations from th e Norristown continuous monitor:

o Continuous measurements run slig htly higher than the corresponding

FRM measurements.

o Jump in hourly concentrations du ring the “morning rush” due to increased highway traffic. This jump is less apparent over the weekend.

o Overnight concentrations are only slightly higher than daytime concentrations. This is probably due to local meteorology with overnight emissions “pooling” under the nighttime inversion then mixing away during the day.

o Weekend concentrations are generally lower than weekday concentrations indicating a strong anthropogenic component.

• Monitors within southeast Pennsylvania generally correlate well with each other though correlations are not as good be tween southeast Pennsylvania and monitors to the west (Lancaster County) and north (Northumberland County).

• The Chester and 500 Broad Street (Ph iladelphia County) monitors do not

correlate as well with other monitors in southeast Pennsylvania suggesting some

deviations at these sites from the overall trends in the region.

1.4 Technical Committees

PA DEP staff in consultation with staff from other state agencies will work together to reach decisions regarding technical issues concerning modeling and monitored design values. Any questions or issues that cannot be answered by this group will be forwarded to the appropriate staff in the U.S. EPA Region III.6 1.5 Participating Organizations

The PA DEP will be the primary developer of the Commonwealth’s modeling demonstration. The Allegheny County Health Department will prepare the modeling demonstration for the Liberty-Clarton annual PM 2.5 nonattainment area in western Pennsylvania. Both agencies maintain peri odic contact with one another during the SIP development process. Other organizations involved in developing the Commonwealth’s modeling demonstration include the Ozone Transport Commission’s (OTC) Modeling Workgroup, the Mid-Atlantic/Nor theast Visibility Union (M ANE-VU) and the Northeast

States for Coordinated Air Use Management (NESCAUM).

1.6 Schedule for Completion

Pennsylvania is currently working with other members of the Ozone Transport Commission’s (OTC) Modeling Workgroup to complete the PM 2.5 modeling demonstration. This modeling demonstrati on builds on the group’s ozone SIP modeling platform. Modeling work should be complete d before the end of 2007 to allow adequate time for the states to prepare SIP demonstrations by April 2008.

2.0 Model and Modeling Inputs

The modeling demonstration for th e Philadelphia-Wilmington annual PM 2.5 nonattainment area relies heavily on the OT C SIP quality-modeling platform. Ozone modeling was the primary focus of this effo rt. This group’s interaction with the MidAtlantic/Northeast Visibility Union (MANE -VU) and the Northeast States for Coordinated Air Use Management (NES CAUM) allowed it, through the regional modeling centers, to do addi tional year-round modeling for PM 2.5 and Regional Haze.

The PA DEP has been an active particip ant in the OTC’s mo deling workgroup. The Department provided the necessary emissions files for Pennsylvania sources needed to run the photochemical grid model used in the SIP modeling platform. The following sections provide brief summaries of the OTC modeling study. More detailed information can be found in the OTC documentation produced as part of this modeling analysis.

Several of these documents are included in the reference section and in Appendix B.

2.1 Selection of Air Quality, Meteo rological and Other Model Inputs

The U.S. EPA’s current guidance does not re commend a particular model or models for

use in a SIP attainment demonstratio n. The OTC modeling committee used the Community Multi-scale Air Quality (CMAQ) photochemical grid model (version 4.5) as part of its SIP modeling platform (OTC Final Modeling Protocol, 2006). CMAQ is a7 Eulerian grid model capable of simulating air-pollutant concen trations in the atmosphere using mathematical equations to charact erize chemical and physical properties.

Meteorological and emission input files mu st be prepared regardless of which photochemical grid model is used. The region al fine-particulate modeling analysis will encompass an entire year of simulation ( 2002). This should provide a good variety of episodes to characterize Phila delphia-Wilmington’s annual PM 2.5 nonattainment.

2.2 Modeling Domain

Figure 2-1 shows the modeling domain used by th e OTC. A nested-gri d approach is used with the lower resolution outer grid provi ding boundary conditions for a more refined grid covering the area of inte rest. The modeling domain wa s chosen to be large enough to properly simulate regional transport. The outer domain boundary is far enough from the inner grid’s boundary so that clean-bounda ry condition assumptions are realistic and probably do not unduly influence concen trations within the inner domain.

Figure 2-1 OTC Modeling Study Domain

Outer grid at 36-kilometer resolution, inner grid at 12-kilometer resolution

2.3 Horizontal and Vertical Grid Resolution

The inner (fine) grid covering the northeas t region and the Philadelphia-Wilmington nonattainment area has a horizontal grid re solution of 12 km. CM AQ’s horizontal grid resolution matches the grid resolution of the meteorol ogical model (MM5). This proposed resolution is with in the upper range of th e fine-grid resolution size8 recommended in the U.S. EPA’s draft m odeling guidance document. The resolution should be adequate to realisti cally simulate regional air-qua lity within the PhiladelphiaWilmington annual PM 2.5 nonattainment area.

The model’s vertical resolution is also in part defined by th e vertical resolution of the meteorological model (MM5). The definition of the vertical structure could also have adopted the one-to-one resolution of the me teorological model. However, based upon prior experience, the vertical extent of the model was set around a height of six to eight km. The number of vertical layers permitted in the model is limited by computational considerations as well as storage limits; t oo many layers increase the amount of time needed to complete a simulation and the am ount of information being stored, processed and exchanged. Limiting the vertical re solution to a few layers, however, would inherently discard the detailed informati on provided by the meteorological model. A compromise solution would be to maintain the high resolution with a one-to-one design of the vertical layers up to approximately one or two km yielding around 7 to 10 levels, followed by a collapse of the MM5 upper la yers to around six to eight km to form another six to eight levels. Thus, under this scenario there would be a total of 13 to 18 layers in the vertical with 7 to 10 levels below two km and the remaining between two and eight km. It should be noted that the mid- point of layer 1 in this analysis is around

10 m.

2.4 Model Initial and Boundary Conditions

The photochemical grid model will be started th ree days before the start of the analysis period using “clean” conditions across the domai n. Prior experiences have shown that a three-day ramp-up period is sufficient to establ ish pollutant levels that are encountered in the beginning of an episode.

In prior studies, attempts ha ve been made to include any information that is available

from monitors that are near the western and northern boundaries of the modeling domain. For this modeling analysis, similar attempts will be made to obtain pollutant data at the boundaries. “Clean” conditions, however, will be assumed for the outer model

boundaries if reliable data is not available.

2.5 Near-Scale Modeling

A near-scale modeling analyses may be n ecessary if the regional model fails to demonstrate that the Philadelphia-Wilmington annual PM 2.5 nonattainment area will meet

the health-basted annual PM 2.5 standard. In this case, the Department will use a Lagrangian or Gaussian model to examin e primary particulate in accordance with applicable guidance. The approach will be similar to what the Allegheny County Health Department has proposed for its Liberty-Clairton annual PM 2.5 nonattainment area.9 2.6 Episode Selection

The OTC modeling study simulated for all of 2002 instead of the episodic approach. This should allow for an adequate analys is of Philadelphia-Wilmington’s annual PM 2.5 nonattainment since it will include periods of low and elevated fine-particulate

concentrations.

Attainment demonstrations have typically been based on a limited number of episodes which are in turn are made up of a limited number of days when pollutant concentrations exceeding the NAAQS. Episodes are chosen on th e basis of peak con centrations and the representativeness of the atmo spheric conditions that typica lly occurred during times of elevated pollutant concentrations . Philadelphia-Wilmington annual PM 2.5 nonattainment area violates the annual fine-particulate standa rd so it is important to consider conditions during the entire year not just epis odes when concentrations are high.

Typically computational and resource constraints limited the number of episodes used in a demonstration. Advances in computer capabilities and expanded resources have permitted groups like the OTC modeling group to simulate longer periods of time. The current OTC modeling study has proposed simulating all of 2 002 using a regional photochemical grid model. This approach ha s several advantages. The first advantage being the greater variety of episodes the m odeling demonstration can examine. This makes the analysis more robust and increases confidence that emission reductions will be beneficial over a number of atmospheric conditi ons that lead to elev ated fine-particulate concentrations. The second advantage is 2002 coincides with the U.S. EPA’s choice to build the base emission inventory. This coincidence will lead to more confidence in the photochemical model’s ability to simulate actu al fine-particulate c oncentrations based on the base inventory (modeled 2002 concentra tions will be based on 2002 emissions and compared with actual monitored 2002 concentrations).

2.7 Meteorological Model

The meteorological files used in CMAQ we re produced using the Pennsylvania State University/National Center for Atmospheric Research ( PSU/NCAR) mesoscale model more commonly know as MM5. MM5 is a limited-area, nonhydrostatic, terrainfollowing sigma-coordinate model designed to simulate or predict mesoscale atmospheric circulation. The model is publicly available and has been used for various air-quality modeling studies in the past. Additional information regarding MM5 can be found in Appendix B (OTC Documenta tion - Meteorological Modelin g using Penn State/NCAR 5th Generation Mesoscale Model, MM5).10 2.8 Emission Inputs

The OTC Modeling Committee also examined two emissions processors (EMS2001 and SMOKE, both using CB4 chemistry) in its prior work and concl uded that there are differences between them that could be minimized by forcing the models to use a common speciation and surrogate database. OTC documentation included in Appendix B (Emission Processing for the Revised 2002 OTC Regional and Urban 12 km Base Case Simulations) details on how the emission inventories were built and processed.

For areas with an attainment date of no later than April 5, 2010 for the annual PM 2.5 NAAQS, the emission reductions need to be implemented no later th an the beginning of the 2009. A determination of attainment will likely be based on air-quality monitoring data collected in 2007, 2008, and 2009. Therefore, the year to project future emissions

should be no later than the la st year of the three-year m onitoring period; in this case

2009.

The 2002 base year emissions inventory sh all be projected to 2009 using standard emissions projection techniques. 2009 i nventories developed by MANE-VU shall be

used in the attainment demonstration. The most recently available inventories from other RPOs in the modeling domain will be used.

Emission inventory guidance doc uments will be followed fo r developing projection year inventories for point, area, mobile, and bioge nic emissions. These procedures address projections of spatial, tempor al, and chemical composition ch ange between the base year and projection year.

The control strategies developed for evaluation in the at tainment demonstration will be selected by the OTC’s Control Strategy Committ ee. These will be selected from groups of strategies developed by the technical subcommittees responsible for identifying and developing the regulations a nd/or control measures.

Consideration will be given to maintaining consistency with control measures likely to be implemented by other modeling domains that ma y be involved in region-wide analysis. Also, technology-based emi ssion reduction requirements ma ndated by the Clean Air Act will be included in the future year model runs.

2.9 Area Examined in the Attainment Demonstration

The Philadelphia-Wilmington annual PM 2.5 nonattainment area is a multi-state nonattainment area consisting of five (5) count ies in Pennsylvania, one in Delaware and three (3) in New Jersey. Three types of fi ne–particulate monitors operated during 2002; FRM samplers, speciated samplers and continuo us monitors. Quarterly relative reduction11 factors (RRFs) will be calculated using the OT C’s modeling results for all monitors in the Philadelphia-Wilmington annual PM 2.5 nonattainment area. RRFs have to be determined

for each PM 2.5 component in accordance with th e U.S. EPA’s modeling guidance

document.

The two speciated monitors operated by the Department did not begin operations until April 2002. RRFs for the first quarter will have to be based on a mean first quarter values or some other methodology in accord ance with the U.S. EPA modeling guidance

document.

Unusual weather conditions contributed to massive fires in the northern portion of Canada’s Quebec province in early July 2002. The plume from this fire impacted both fine particulate and ozone concentrations acr oss much of the north east for several days (Northeast Oxidant and Particle study NE -OPS, 2002). Data (J uly 6-9, 2002) from

almost all of the FRM monitors in sout heast Pennsylvania including Chester were invalidated as an “exceptional even t” under the U.S. EPA guidelines.

2.10 Quality Assurance

All air quality, emissions, and meteorologi cal data will be reviewed to ensure completeness, accuracy, and consistency befo re proceeding with modeling. Any errors, missing data or inconsistencies, will be a ddressed using appropriate methods that are consistent with standard practices.

Quality Assurance (QA) activities will be carried out for the various emissions, meteorological, and photochemical mode ling components of the modeling study.

Emissions inventories obtained from the va rious Regional Planning Organizations (RPO) will be examined through the use of quality assurance software, algorithms, and plotting routines to check for errors in the emissions estimates. When such errors are discovered, the problems in the input data files shall be corrected.

Emission inventories from the MANE- VU RPO are currently undergoing final preparation and quality assura nce tests. The OTC intends to use the most current emission inventory data from the other RPOs that are contained within the modeling domain. The other RPOs may revise th eir emission inventories after the OTC commences its modeling analysis. These changes will not be incorporated into the OTC’s modeling analysis due to time constr aints. Emission inventory changes made by the other RPOs are expected to be small a nd therefore only contribute to minor changes in fine-particulate concentrations within the OTR.

The MM5 meteorological and CMAQ air quality model inputs and outputs will be plotted and examined to ensure accurate representa tion of the observed data in the model-ready fields, and temporal and spatial consistenc y and reasonableness. Both MM5 and CMAQ will undergo an operational/scien tific evaluation and this wi ll facilitate, among other things, the quality assurance review of the meteorological and air quality modeling procedures. Data sets availa ble to support this quality assu rance of the aer ometric inputs12 include the routine synoptic-s cale data sets from the NWS 12-hourly rawinsondes and three-hourly surface observations. These data include the horizontal wind components (u and v), temperature (T), and relative humidity (q) at the standard pr essure levels, plus sea-level pressure (SLP) and ground temperature (Tg).

The OTC Modeling workgroup has comple ted several analyses of the MM5 meteorological files used in the group’s modeling analysis. Analyses of the MM5 meteorological fields are locat ed in Appendix C. OTC’s mo st resent analysis of MM5

was to examine the effects of different Pl anetary Boundary Layer (PBL) schemes on the meteorological fields. Three different PBL sc hemes were examined using meteorological information including temperature, wind sp eed, wind direct and humidity from over 600 National Weather Service (NWS) and CASTNet (C lean Air Status and Trends Network). MM5 was found to produce meteorological fields that were in general agreement with corresponding observations.

3.0 Model Performance Evaluation

A model performance evaluation will be conduc ted to ensure the regional photochemical model is simulating fine-particulate concentr ations in a reasonable fashion. If the regional photochemical model re produces the fine-particulate components well, then it lends more credibility to the model’s ability to simulate fine-particulate concentrations correctly for the control strategy runs.

3.1 Ambient Data Base

Model evaluations will need to be comple ted on all fine-particulate components.

Evaluation matrices from the U.S. EPA’ s draft modeling guidance document will be used. It is important that the regiona l photochemical model simulate the highest contributing fine-particulate components corr ectly. In Philadelphia-Wilmington annual

PM 2.5 nonattainment area’s case this would be sulfates, nitrates and organic carbon. Results from PA DEP’s speciated PM 2.5 monitor will be used in this analysis.

There are several additional s ources of fine-particulate meas urements that could be used in the model performance evaluation. Th ese include Philadelphia-Wilmington’s FRM and continuous fine-particulate measurements and results from an acid rain monitoring site near Valley Forge. Data from the acid rain site is of limited use because the site only started collecting datain November of 2002.

Other performance evaluation measures will ha ve to be developed if the Department has

to do additional “near-scale” mode ling to demonstrate attainment.13 3.2 Evaluation Procedures

The U.S. EPA guidance will be used to evaluate model performance. Model PM 2.5 bias statistics will be developed in accordance w ith section 18.4.2 of the guidance. These will

be used to determine each PM 2.5 component’s bias. Any large bias in PhiladelphiaWilmington’s sulfate, nitrate or organic PM 2.5 components will be problematic. Initial model results presented at the OTC’s mode ling committee member’s meetings suggest CMAQ simulates sulfate concentrations quite well.

Continuous and FRM data will be used in a re lative fashion to determine if there are any temporal biases in the model. These data sets contain more information than the speciated data sets because their collection frequency is greater, once every three days and hourly, versus the once every si xth day for the speciated data.

4.0 Attainment Demonstration and other Supplemental Analyses

The modeled attainment demonstration cons ists of analyses that estimate whether

selected emissions reductions will result in ambient concentrations that meet the NAAQS, and an identified set of control m easures which will result in the required

emissions reductions. The attainment demons tration estimates the amount of emission reduction needed to demonstrate attainment by using a modeling attainment test.

Additional analyses may also be performed to indicate that a proposed emission reduction will lead to attainment of the NAAQS. The mo deled attainment test predicts whether or not all estimated future annual fine-particulate design values will be less than or equal to the concentration level specified in the NAAQS under meteorological conditions similar

to those which have been simulated.

4.1 Model Attainment Test

The modeled PM 2.5 attainment test applied at each nonattainment monitor will follow the recommended procedures outline in the U.S. EPA’s modeling guidance document. In order to perform the recommended modeled a ttainment test, Stat es should divide

observed mass concentrations of PM 2.5 into 6 components 5 :

• mass associated with sulfates (SO 4 );

• mass associated with nitrates (NO 3 );

• mass associated with organic carbon (OC);

• mass associated with elemental carbon (EC);

• mass associated with inorganic particul ate emissions, excluding primary sulfate

and

• nitrate particles (IP);14 • unattributed mass (i.e., the di fference between measured PM 2.5 and the sum of the other 5 components) (U).

To apply the test, States must first have run an air quality model at least twice to simulate

current emissions and to simulate the net effects of a proposed control strategy and growth projected to two years prior to the required attainment date. The Department will then follow the recommended procedures to develop the appropriate RRFs for each component. For each monitoring site, obtain modeled estimates for 5 of the 6 major components of observed PM 2.5 (i.e., SO 4 , NO 3 , OC, EC and IP). For each 3-month quarter, calculate site (i) and co mponent (j) specific relativ e reduction factors (RRF) ij . The

relative reduction factor for co mponent j at a site i is give n by the following expression:

(RRF) ij = ([C j, projected ]/[C j, current ]) I

where,

C

j, current is the quarterly mean concentration pred icted at or near the monitoring site

with emissions characteristic of the period used to calculate the current design value for annual PM 2.5 (e.g., 2000-2002);

C

j, projected is the quarterly mean concentration predicted at or near the monitoring site two years prior to the required a ttainment date (e.g., 2010 in an area having a 2012 attainment date).

Assume that the relative reduction factor for the sixth previously id entified component of

observed PM 2.5 (i.e., “U”) is “1.00". Apply each co mponent-specific relative reduction

factor to the observed aver age quarterly mean concen tration of the corresponding component, derived in step 1. Add the 6 components to obtain a projected average quarterly mean PM 2.5 concentration.

4.2 Unmonitored Area Analysis

In the event that it is necessary to estimate design values at unmonitored locations within the Philadelphia-Wilmington nonattainment area, an “unmonitored area analysis” using model adjusted spatial fields may be performe d. The basic steps of this process are as

follows:

1. Interpolate ambient design value data to create a set of spatial fields.

2. Adjust the spatial fields using grid ded model output grad ients (base year values).

3. Apply gridded model RRFs to the model adjusted spatial fields.

4. Determine if any unmonitored areas ar e predicted to exceed the NAAQS in

the future.

Recommended U.S. EPA guidance shall be uti lized in the “unmonitored area analysis”.15 4.3 Additional Analyses

Corroboratory evidence shall accompany the mode l attainment demonstration. The U.S. EPA guidance for supplemental analyses and weight of evidence (WOE) demonstrations shall be followed. Table 1-2 summarizes the U.S. EPA guidelines used to determine if a

WOE demonstration is needed.

The weight of evidence submittal, if necessa ry, shall describe the analyses performed, databases used, key assumptions and outcomes of each analysis, and why the evidence, viewed as a whole, supports a conclusion th at the area will attain the NAAQS despite the model predicted future design value, or conve rsely, demonstrate that reaching attainment is not likely despite passing the model attainment test. WOE analysis performance and type will be dictated by the U. S. EPA’s final modeling guidance.

5.0 Procedural Requirements

A range of documents will be prepared and referenced during the SIP process. Documents pertaining to the modeling analysis in support of Pennsylvania’s SIP for the Philadelphia-Wilmington annual PM 2.5 nonattainment area will be made available as soon as practical for all interest ed parties. Additional docu mentation for the OTC Modeling Committee as part of its regiona l modeling analysis will be re ferenced and included in the

documentation.

Table 1-2 Summary of PM 2.5 WOE Guidelines (from the U.S. EPA Guidance)

Results of Modeled Attainemen t Test Supplemental Analyses

Annual PM 2.5 24-Hour PM 2.5

Future Desi g n Value

< 14.5 μ g/m 3 , all sites Future Desi g n Value

< 62 μ g/m 3 , all sites Basic supplemental analyses should be completed to confirm the outcome of the

modeled attainment test

Future Design Value

14.5 – 15.5 μ g/m 3 , all

sites Future Design Value 62

– 67 μ g/m 3 , all sites A weight of evidence demonstration

should be conducted to determine if aggregate supplemental analyses support

the modeled attainment test

Future Desi g n Value

≥ 15.5 μ g/m 3 , all sites Future Desi g n Value

≥ 68 μ g/m 3 , all sites More qualitative results are less likely to support conclusion differing from the

outcome of the modeled attainment test16 5.1 Reporting

Documents, technical memorandums, and data bases developed in this study will be submitted to all parties for review and subsequent distribution as appropriate. The various work products developed in preceding ta sks will be synthesized and integrated to produce a draft Technical Support Document (TSD) that describes the full range of technical and modeling ac tivities performed during the projec t. This report will contain

the essential methods and results of the c onceptual model, epis ode selection, modeling protocol, base case model development and pe rformance testing, future year and control strategy modeling, quality assurance, weight of evidence analyses, and calculation of

PM 2.5 attainment via the U.S. EPA’s rela tive reduction factor (RRF) methodology.

The PA DEP is the responsible agency for conducting and submitting a regional modeling attainment demonstration for June 15, 2009 to the U.S. EPA. All parties will

work to establish a suitable outline for the TSD within the framework. A final TSD will be developed after receiving reviewer’s comments.

5.2 Data Archive and Delivery of Modeling Files

All relevant data sets, model codes, scripts, and related so ftware required by any project participant necessary to co rroborate the study findings (e .g., performance evaluations, control strategy runs) will be provided in an electronic format. The Department will be responsible for the archival of all modeling data relevant to th is project. Transfer of data may be facilitated thr ough the combination of a project we bsite and the transfer of large databases via overnight mail.

The department will work with U.S. EPA Region III staff to develop a full list of deliverables prior to the submittal of the final SIP demonstration.

6.0 References

The Modeling Committee of th e Ozone Transport Commission

, A Modeling Protocol for the OTC SIP Quality Modeling System For Assessment of the Ozone National Ambient Air Quality Standard in the Ozone Transport Region , March 2006.

NorthEast Oxidant and Particle Study (NEOPS), Final Report to the Commonwealth of Pennsylvania , July 2003.

The United States Enviro nmental Protection Agency

, Guidance on the Use of Models and Other Analyses for Demonstrating Atta inment of Air Quality Goals for Ozone, PM2.5, and regional Haze, April 2007 (EPA –454/B-07-002).A Appendix A. Mid-Atlantic Regional Air Ma nagement Association (MARAMA)

A Guide to Mid-Atlantic Regional Air Quality

< MARAMA report attached as a pdf document >

http://www.marama.org/reports/Guide-MidAtlantic_RegAQ_Final.pdfA Appendix B.

Summary of Pennsylvania’s PM 2.5 Nonattainment ProblemB Appendix C.

Correlation Analysis: Southwest, Southcentral and Southeast PennsylvaniaA Appendix D.

OTC DocumentationB Appendix E

OTC Modeling Committee – Meteoro logical Modeling Analysis