United States
       Environmental Protection
       Agency
            Office of Air Quality
            Planning and Standards
            Research Triangle Park, NC 27711
EPA-454/R-92-001
May 1992
EPA
INTERAGENCY WORKGROUP ON
AIR QUALITY MODELING (IWAQM)
WORK PLAN RATIONALE

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                            EPA-454/R-92-001
INTERAGENCY WORKGROUP ON
AIR QUALITY MODELING (IWAQM)
WORK PLAN RATIONALE
                            U.S. Environmental Protection Agency
                            Region 5, Library (PL-12J)
                            77 West Jackson Boulevard, 12th Floor
                            Chicago, !L 60604-3590
    Office of Air Quality Planning and Standards
       Technical Support Division (MD-14)

   Research Triangle Park, North Carolina 27711


               May 1992

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                             NOTICE

     The information in this document has been reviewed in its
entirety by the U.S. Environmental Protection Agency (EPA), and
approved for publication as an EPA document.   Mention of trade
names, products, or services does not convey, and should not be
interpreted as conveying official EPA approval, endorsement, or
recommendation.
                               ii

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                             PREFACE

     The Interagency Workgroup on Air Quality Modeling  (IWAQM)
was formed to provide a focus for development of technically
sound regional air quality models for regulatory assessments of
pollutant source impacts on Federal class I areas.  Meetings were
held with personnel from interested Federal agencies, viz. the
Environmental Protection Agency, the U.S. Forest Service, the
National Park Service and the Fish and Wildlife Service.  The
purpose was to review respective regional modeling programs, to
develop an organizational framework, and to formulate reasonable
objectives and plans that could be presented to management for
support and commitment.  The members prepared a memorandum of
understanding (MOU) that incorporated the goals and objectives of
the workgroup and obtained signatures of management officials in
each participating Agency.  Although no States are signatories,
their participation in IWAQM functions is explicitly noted in the
MOU.

     This Status Report and Work Plan Rationale is the first
document published by IWAQM in an effort to inform the sponsoring
Agencies and other interested parties about IWAQM activities.
IWAQM members anticipate issuing additional publications related
to the Workgroup's further plans, progress toward meeting goals
and objectives, the results of model evaluation studies, proposed
and final recommendations on modeling systems for regulatory
applications, and other topics related to specific objectives in
the MOU.

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                         ACKNOWLEDGEMENTS

     The members of IWAQM acknowledge the special efforts of the
Chairman, Mark Scruggs of the National Park Service, for adroitly
managing the preparation of this document, John Viroont of the
National Park Service for composing the contents and John Irwin
of the Environmental Protection Agency for developing the Work
Plans and implementing the program for funding them.
                               iv

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                             CONTENTS




PREFACE    	iii




ACKNOWLEDGEMENTS   	   iv




FIGURES	Vi




I.     BACKGROUND    	   1




II.    OBJECTIVES    	   1




III.   APPROACH	,	   1




IV.    MEASURES	   2




V.     MODEL ATTRIBUTES   	   3




VI.    CANDIDATE MODELS   	   4




VII.   CURRENT STATUS     	   4




VIII.  RECOMMENDED ACTIONS  	   4




IX.    REFERENCES	'	H




APPENDIX A.  MEMORANDUM OF UNDERSTANDING  	   12




APPENDIX B.  LISTING OF WORKGROUP MEMBERS   	   16

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                             FIGURES




Number                                                       Page




1     WORK PLAN - PHASE 1, 1992   	   5




2     PROJECT TIMELINE - PHASE 1  	   5




3     WORK PLAN - PHASE 2	   8



4     PROJECT TIMELINE - PHASE 2  	   9




5     PROJECT TIMELINE - PHASE 2 (CONT.)  	  10
                                Vi

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I. BACKGROUND

     The United States Environmental Protection Agency  (EPA), the
United States Forest Service (USFS), the United States Fish  and
Wildlife Service  (FWS), and the National Park Service (NPS)  have
entered into a memorandum of understanding (MOU) to cooperate in
the developing, testing, and applying of air quality
dispersion/simulation models (Appendix A).  These models are
needed to estimate pollutant concentrations on a regional scale,
including the individual and cumulative impacts of proposed  and
existing sources  on Air Quality Related Values  (AQRVs),
Prevention of Significant Deterioration (PSD) increments, and
National Ambient  Air Quality Standards (NAAQS), with emphasis on
Federal class I areas.  To carry out this agreement a working
group has been formed, known as the Interagency Workgroup for Air
Quality Modeling  (IWAQM).  A list of workgroup members is given
in Appendix B.

     Coincidentally, Congress recognized the need to support the
development of such a modeling capability.  A special
appropriation bill sponsored by Representative Tom Bliley of
Virginia granted  EPA $700,000 (for fiscal year 1992) for
"identifying and  evaluating sources of visibility impairment in
class I areas."   The work plan described herein has been tailored
to be consistent  with, and responsive to, this special
appropriation.
II. OBJECTIVES

     The objective of IWAQM is to review existing modeling
techniques to recommend a credible, regional scale model capable
of providing the necessary information to assess AQRVs in class I
areas as well as attainment of the NAAQS and regional scale PSD
increment consumption.  It is desired that the computer resources
needed to access the recommended modeling system for most
applications be comparable to resources typically available to
State and local air pollution control agencies.  This promotes
(but does not limit) the computer requirements to those of a
Reduced Instruction Set Computer (RISC) architecture work station
or a high-end personal computer.


III. APPROACH

     Following several meetings and deliberations the IWAQM
intends to implement a phased approach in order to satisfy the
modeling needs described above.  Phase 1 consists of reviewing
EPA guidance and recommending a modeling approach to meet the
immediate need for a regional scale model for ongoing permitting
activity.  This recommendation will likely be based on current
EPA guidance and existing empirical models.  During Phase 2 the

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workgroup will augment Phase 1 with a review of other available
models and make a recommendation of the most appropriate modeling
techniques.  This recommendation will likely represent a
compromise between the current modeling state-of-science and best
available operational computer capabilities.  The IWAQM
recognizes this later recommendation may change the initial,
first phase, interim recommendation.  In Phase 3 the workgroup
will add more advanced modeling techniques to its consideration
and recommend a more permanent solution, probably representing a
greater level of scientific and computer hardware sophistication.

     During Phase 1 and 2, improvements to existing modeling
systems will likely be identified.  The products of Phase 2 and 3
are anticipated to be models which have been thoroughly tested
and appraised.  The final Phase (3) will consider the long-term,
optimum modeling needs.

     In order to focus this effort, increase the chance for
success in at least certain scenarios, and to meet an articulated
immediate need of permitting authorities, and the EPA, IWAQM will
address only sulfur and nitrogen derived pollutants in the
immediate future.  We acknowledge that there are other pollutants
such as photochemical oxidants that may injure components of the
natural ecosystem, but assessment by IWAQM of the modeling needs
and development of oxidant effects modules is postponed until a
later date.
IV. MEASURES

     Based on the information available to the IWAQM, the
committee has compiled a preliminary list of measures that AQRV
models must be able to address to be useful for the Federal Land
Managers (FLMs) in their deliberations of the impact on federal
lands.  These measures are somewhat different for each component
of the natural ecosystem and include estimates for the
concentration of a variety of chemical species, pollutant
exposure, pollutant deposition, and total pollutant loading for a
variety of averaging times and units.  The specific list of
measures for assessing effects on visibility, aquatic, and
terrestrial ecosystems is indicated below.

Visibility

     The modeling system must be capable of assessing visibility
effects of coherent plumes and regional haze from sulfur-based
and nitrogen-based air pollutants, organics, elemental carbon,
soil, and process derived fugitive emissions.  It is important
that the modeling system be able to simulate averaging periods as
short as 1-hour.  At a minimum, the system must be capable of
producing concentrations of particles, SO^,  NO^, and NO,.   The
modeling system must account for the oxidation mechanisms in the

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formation of SO^ and NOj.   The system must account for both the
gaseous and aqueous phase  oxidation pathways for SOT.   Relative
humidity fields must be included for visibility analysis.  In
addition to the atmospheric transport and dispersion model
results, data must be available regarding the vertical profiles
of relative humidity and temperature as a function of time of
day, season and location.  These are required for a visibility
effect calculation in a post-processor or independent visibility
effects module.

Aquatic Ecosystems

     The modeling system must provide information needed to
assess the ecological effects of deposited pollutants onto water
surfaces .and through hydrologic processes, such as lake and
stream acidification, for  monthly, seasonal, and annual periods.
The modeling system must be capable of calculating both dry and
wet deposition of SO£ and NO^, which necessitates precipitation
calculations.  The atmospheric model needs to generate the
parameters necessary to run independent hydrologic and chemical
assessment models and to estimate the amount of deposition of
toxic chemicals.

Terrestrial Ecosystems

     The modeling system must provide information needed to
evaluate the terrestrial effects, such as tissue damage or
mortality or decreases in  growth, of atmospheric pollutants from
toxics, sulfur dioxide, sulfuric acid mist,  herbicides, and
pesticides for averaging times ranging from 1-hour to several
years.  The atmospheric model should characterize the pollutant
contribution to the ecosystem in terms of deposition, total
loading, and ambient concentration.
V. MODEL ATTRIBUTES

     The models thus far considered by IWAQM are on both Eulerian
and Lagrangian frameworks and meet the following criteria:

     A.   Use spatially and temporally varying meteorological
          fields to include, precipitation, wind, and
          temperature.

     B.   Include at least first order sulfur and nitrogen
          oxidation chemistry.

     C.   Include treatment for effects of complex terrain on the
          meteorological fields in consideration of land use and
          on the transport and dispersion.

     D.   Treat extended periods of regional stagnation.

                                3

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     E.   Couple pollutant transport, dispersion, and deposition
          with meteorological fields.

     F.   Include cloud and aqueous phase chemistry which allows
          the calculation of chemical transformation and direct
          cloud impacts on terrain.

     G.   Account for the effects of aerosol/particle size
          distribution on radiative transfer processes.

     H.   Include treatment of wet and dry deposition processes.

     I.   Include a modeling domain of North America (RADM-
          boundary) for purposes of establishing boundary
          conditions.  The specific model domain is capable of
          being specified on a case-by-case basis.

     The IWAQM may identify other desirable qualities of the
modeling system in the course of its review.  The models
identified do not necessarily need to meet all of the
aforementioned criteria initially, but should be structured such
that they can be easily modified to meet these criteria.


VI. CANDIDATE MODELS

     To initiate Phase 1 evaluations, IWAQM identified a
preliminary list of existing regional scale models which
currently meet, or with minor modifications, will satisfy the
criteria identified above.  All of these models empirically
determine the meteorological fields to which a dispersion model
is applied.  As such, they represent models that rank, in level
of sophistication and operational complexity, somewhere between
traditional single-source Gaussian and first-principle models.
These models are:

     ARM3 (Morris et al., 1988)
     MESOPUFF-II  (Scire et al. , 1984)
     CALMET/CALPUFF (Scire et al., 1990a,b)
     NUATMOS/CITPUFF (ROSS et al., 1988)
VII. CURRENT STATUS

     Results of preliminary sensitivity tests with ARM3 and
MESOPUFF-II suggest that an unqualified application of those
models to an arbitrary scenario may be unadvisable.  These tests
call to question the ability of these models to generate
physically reasonable meteorological fields (particularly mixing
height).  In part, the questionable results occur because the
models must attempt to generate meteorological fields from
observations that are significantly separated in space and time.

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VIII. RECOMMENDED ACTIONS

Phase 1

     As shown in Figures 1 and 2, the Work Plan and timeline
for Phase 1, the NPS will continue to conduct sensitivity
analyses of ARM3 and MESOPUFF-II, to determine which of these


               FIGURE  1.  WORK PLAN  -  PHASE 1,  1992
1A. SENSITIVITY ANALYSES OF
MESOPUFF-II, ARM3 (EXAMINATION OF
GENERATED METEOROLOGICAL AND
CONCENTRATION FIELDS).
2A. VISIBILITY MODULE (FIRST ORDER
APPROXIMATION) .
IB. EXAMINATION OF THE COUPLING OF 1A AND 2A.
1C. DOCUMENT RECOMMENDED APPROACH. |
              FIGURE 2.  PROJECT TIMELINE - PHASE 1
1992
MONTH
1
2
3
4
5
6
7
8
TASK 1
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models will best meet the immediate needs of State and permitting
authorities.  The NPS will also document a simple visibility
module that relates the change in atmospheric extinction with
model-estimated sulfate and nitrate concentrations and couple
this module with the meteorological and dispersion model
recommended during this phase.

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Phase 2

     The IWAQM has discussed the relative merits of various
empirical modeling approaches for producing four dimensional
meteorological fields.  From the discussions, a number of serious
disadvantages to  empirical approaches have been identified.  The
disadvantages of  empirical approaches could be resolved using a
model, based on the primitive equations of motion of the
atmosphere.  The  disadvantage to this, however, is that such
models typically  require technical staff with a high degree of
expertise in this area and extensive computer resources.  This
latter requirement has been drastically eased with the rapid
advent of new computer technologies.  The need for highly
specialized staff, however, does not meet one of the essential
needs identified  by IWAQM, namely, a system that can be
implemented by an individual State with limited resources.

     During its discussions, IWAQM has identified a possibly
viable alternative.  A primitive equation meteorological model
with four dimensional data assimilation, MM4-FDDA, has been
successfully run  for a number of cases under the NAPAP program
(Stauffer and Seaman, 1990 and Stauffer et al., 1991).  This
model is available to the EPA Office of Research and Development
(ORD) .  The system has previously been run with an 80 kilometer
resolution.  We suggest that the 80 kilometer resolution
meteorological fields, generated on an hourly basis by the MM4-
FDDA system, be used as the base input to the various meso-scale
modeling systems  being examined by the IWAQM.  These fields would
eventually be generated by ORD for the continental United States
for an entire year, but first, the viability of this approach
would be demonstrated with a smaller data set.

     Ultimately the desire is to use all of the meteorological
fields generated  by the primitive equation model as direct input
to the air quality model(s) chosen by the IWAQM.  The IWAQM
recommends an interim approach using these meteorological fields
to generate "soundings" every 80 kilometers and then using these
as input to the various meteorological drivers of the chosen air
quality models.

     Phase 2 has  been prepared to implement this proposed
alternative solution.  The Work Plan and timeline is shown in
Figures 3, 4 and  5.  We anticipate that the plan can be
implemented with  the funds from the special appropriation (for
EPA, USFS, and NFS contractor support) with some supplemental NFS
project funds in  1992 and 1993,  and in-kind services from the
EPA, NPS, and USFS.  Briefly the plan calls for:

     The NPS to proceed with the modification of the NPSAQMS and
     MESOPUFF-II  so that these models can use the meteorological
     fields prepared by MM4-FDDA, conduct sensitivity analyses

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     with MM4-FDDA data, and document model adaptations and
     sensitivity test results.

     The USFS to proceed with modification of the CITPUFF/NUATMOS
     so that these models can similarly use the MM4-FDDA meteoro-
     logical data, conduct sensitivity analyses, and document
     model adaptations and results of sensitivity test results.

     EPA ORD to generate and provide access to gridded MM4-FDDA
     meteorological data.

     EPA OAQPS to hire a contractor to conduct a similar
     assessment of the CALPUFF model and conduct an assessment of
     the performance of all the models on the preliminary list
     given above.

     EPA to provide a special tracer data base on which to
     conduct additional model sensitivity analyses.

-    The EPA and NPS to retain a contractor to develop and
     document a visibility module (representing a substantial
     upgrade of the module proposed in Phase 1) to add to the
     complete IWAQM modeling package.

     The EPA to retain a contractor to update the visibility
     workbook to improve VISCREEN parameter interpretations, to
     correct any errors in the PLUVUE II code, and clarify the
     discussion on the application and interpretation of PLUVUE
     II.

     IWAQM will use the information thus generated to make a
recommendation as to the most appropriate modeling technique(s)
for use in assessing AQRVs in class I areas as well as regional
scale PSD increment consumption.

     The final, major activity in Phase 2 (II) is the regulatory
proposal of the recommended modeling technique(s) for use in
assessing the impact on AQRVs,  PSD regional increment consumption
and the NAAQS in class I areas.  This is anticipated to involve
publishing a notice in the Federal Register and soliciting public
comments on proposed revisions to the Guideline on Air Quality
Models.  There will be a public hearing/meeting, review of public
comments, preparation of responses and final rulemaking.  IWAQM
will also arrange for training on the recommended system as well
as publication of the user's manuals and related regulatory
guidance.

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                    FIGURE 3.   WORK PLAN  - PHASE 2
1A. INDIVIDUAL ANALYSES
OF METEOROLOGICAL
PROCESSORS

  -  (NFS XNHOUSE)
  -  (USFS/EPA
CONTRACTOR)
  -  (EPA CONTRACTOR)
2A. SENSITIVITY
METEOROLOGICAL DATA
(USE EXISTING DATA)
3A. VISCREEN UPDATE
                         -  (EPA CONTRACTOR)
IB. COMPARISON/SUMMARY
OF SENSITIVITY ANALYSES
OF METEOROLOGICAL
PROCESSORS

  -  (EPA CONTRACTOR)
2B. RETRIEVAL/DATA
MANAGEMENT SYSTEM
3B. STATE-OF-PRACTICE
VISIBILITY MODULE
                         -  (NFS CONTRACTOR)
                         -  (EPA CONTRACTOR)
1C. IWAQM EVALUATION OF
SENSITIVITY ANALYSES OF
METEOROLOGICAL
PROCESSORS
2C. CONSTRUCT MM4-
FDDA DATA ARCHIVE
(NEW GENERATION)

  - (EPA CONTRACTOR)
ID. INDIVIDUAL ANALYSES
OF DISPERSION MODELS
(COMMON METEOROLOGICAL
PROCESSOR)

  -  (NFS INHOUSE)
  -  (USPS/EPA
CONTRACTOR)
  -  (EPA CONTRACTOR)
2D. EVALUATION MM4-
FDDA DATA SET
(SPECIAL EVALUATION
DATA)
  - (EPA CONTRACTOR)
IE. COMPARISON/SUMMARY
OF SENSITIVITY ANALYSES
OF DISPERSION MODELS

  -  (EPA CONTRACTOR)
IF. IWAQM EVALUATION OF
SENSITIVITY ANALYSES OF
DISPERSION MODELS
1G. EVALUATION OF PHASE
1 AND 2 MODEL SYSTEMS

  -  (EPA CONTRACTOR)
1H. IWAQM SUMMARY
RECOMMENDATIONS
II. REGULATORY REVIEW
AND DISSEMINATION
                                     8

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               FIGURE 4.  PROJECT TIMELINE - PHASE  2
   1992
  MONTH
TASK 1
TASK 2
                                                   TASK 3
   10
   11
   12
                                          3A.
                          HETEOROLOGIGAL
                          2B..
                   at '
         METEOROUX3ICAL
         PROCESSORS  ?
                                        3B.
Phase 3

     It is premature to scope out future IWAQM activities in
detail.  We  anticipate that IWAQM will continue to conduct
sensitivity  analyses and evaluation of models in Phase 2,
consider other modeling alternatives,  and investigate the
feasibility  of adding modules for estimating terrestrial and
aquatic ecosystems  effects.   As progress is made, IWAQM will
periodically report on its findings and recommendations for
future activities.

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          FIGURE 5.   PROJECT TIMELINE  - PHASE 2  (CONT.)
1993/
 1994
MONTH
TASK 1
TASK 2
   TASK 3
        IB,  1WAQK SUHMMHf
        09 DISPERSION
        MODEL SENSITIVITY
        RESULTS  -   """,.
              2A. AND 2B.
             iCQNTIMUED FROM
              1S92
        IF,  IWAQM
        BVM#«TIO»?
        0ISPKRSION
                  OF 1-Y8AR
             DATABASE USJUG
             lffl4~FDDA
       ccanswocsoar
       AVAILABLE DATA;
       VISIBILITY MODULE
       FROW
    2D,
    OF ffii4~FDDA
    DATA SET
3B.
.CONTINOED
FROM  1992
 10
 11
 12
 (FBOM
                              2|
   ?OR USER,
                              o? TIKAI, PHAS® 2
                                  DISSEMINATION
                                   10

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IX.  REFERENCES

Morris, R.E., Kessler, R.C., Douglas, S.G.,  Styles, K.R., and
     Moore, G.E.,  (1988):  Rocky Mountain Acid Deposition
     Model Assessment:  Acid Rain Mountain Mesoscale Model
     (ARM3).  EPA-600/3-88/042, NTIS PB89-124408,
     Environmental Protection Agency, Research Triangle
     Park, NC,  318 pp.

Ross, D.G., Smith, I.N., Manins, P.C., and Fox, D.G.,  (1988):
     Diagnostic wind field modeling for complex terrain:
     model development and testing.  J. Appl. Meteor.,
     27(7):785-796.

Scire,  J.S., Insley,  and Yamartino, R.J.,  (1990a):  Model
     Formulation and User's Guide for the CALMET Dispersion
     Model.  California Air Resources Board,  Sacramento, CA,
     278 pp.

Scire,  J.S., Strimaitis, D.G., and Yarmartino, R.J.,  (1990b):
     Model Formulation and User's Guide for the CALPUFF
     Dispersion Model.  California Air Resources Board,
     Sacramento, CA,   344 pp.

Scire,  J.S., Lurmann, F.W., Bass, A., and Hanna, S.R.,   (1984):
     User's Guide to the Mesopuff II Model and Related
     Processor Programs.  EPA-600/8-84-013.   NTIS PB84-
     181775.  Environmental Protection Agency, Research
     Triangle Park, NC,  214 pp.

Stauffer, D.R. and Seaman, N.L.,  (1990):  Use of four-
     dimensional data assimilation in a limited-area
     mesoscale model.  Part I:  Experiments with synoptic-
     scale data.  Mon. Wea. Rev., (118):1250-1277.

Stauffer, D.R., Seaman, N.L. and Binkowski,  F.S.,  (1991):  Use
     of four-dimensional data assimilation in a limited-area
     mesoscale model.  Part II:  Effect of data assimilation
     within the planetary boundary layer.  Mon. Wea. Rev.,
     (119):734-754.
                               11

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                                  APPENDIX A


                                        NPS  AGREEMENT NO.  1443-MU-001-92-002

                        MEMORANDUM OF UNDERSTANDING

                                 AMONG THE

                    U.S.  ENVIRONMENTAL PROTECTION AGENCY

                            U.S. FOREST SERVICE

                       U.S.  FISH AND WILDLIFE SERVICE

                                  AND THE

                           NATIONAL PARK SERVICE
Article I.    This agreement is entered into to foster cooperation among the
              United States Environmental Protection Agency (EPA), the United
              States  Forest  Service   (USFS),  the  United States  Fish  and
              Wildlife Service  (FWS) and  the National  Park  Service (NPS)  in
              developing,     testing,     "and    applying    air     quality
              dispersion/simulation models.   This agreement is pursuant  to
              Section 320 of the Clean Air Act (42 U.S.C.  7620) and Sections
              901(b) and 816 of the Clean Air  Act Amendments of 1990, which
              respectively  amend  and  add Section  103(e)(3)  and  Section
              169B(a)(l)(C) to  the Clean Air Act  (42  U.S.C. 7403(e)(3)  and
              7492).  Specifically, the agreement  relates to the development,
              evaluation, and application of mathematical modeling techniques
              that  can  be used to estimate pollutant concentrations on  a
              regional scale,  including the individual  and cumulative impacts
              of proposed and existing sources on air quality related values
              (AQRVs),  PSD increments,  and  National Ambient Air  Quality
              Standards (NAAQS), with emphasis  on  Federal class I areas.  The
              output from such models  is needed by Federal Land Managers,  and
              others, to make informed decisions regarding the  protection of
              natural resources.

Article II.   Advanced air  quality simulation modeling techniques  that  can
              assess the regional  impacts  from air pollutant emissions have
              historically not been readily available or frequently applied.
              To date, the  EPA, USFS,  and NPS have  independently explored,
              with limited success, the adequacy of various computer-assisted
              approaches.   However,  in  order to  ensure the  development,
              acceptance,  and  application  of  a  consistent  air  quality
              simulation modeling  approach to  our common  air quality impact
              assessments,  the EPA,  USFS, FWS,  and  NPS  agree  to  form  a
              working group, to be known  as  the Inter-agency Work-group for
              Air Quality  Modeling (IWAQM).   The Work-group  shall  meet  at
              least semi-annually  and  confer frequently by telephone.   The
              Work-group shall  be  comprised of at  least  one  representative
              from  the  EPA's Offices  of Research  and Development  and  Air
              Quality Planning and Standards,  an EPA Regional Office,  the
              NPS-Air Quality  Division,  the FWS-Air Quality Branch and the
                                        12

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Article III,
USFS.  A member of this group shall be selected as chair by the
Work-group  and the chair shall be  rotated among the  members
annually.

The objectives of the Work-group shall include:

A.     Review,   on  a  continuing  basis,  the  progress   of
       appropriate air quality simulation model development and
       evaluation  efforts  occurring  within  each  member's
       organization,  between  members'  organizations,  or  by
       other relevant groups;
               B.
               E.
               F.
              G.
              H.
       Identify  candidate  air  quality  simulation  modeling
       techniques,the  criteria by  which  the  performance  of
       those  modeling  techniques  shall  be  evaluated,   and
       sponsor suitable performance evaluations;
                      Provide  the   opportunity  for   State  agencies
                      participate in Work-group  functions;
                                                            to
       Identify, following the performance evaluation, the most
       appropriate air quality simulation modeling technique (s)
       for  use in class  I analyses  under various  transport
       conditions;

       Ensure  that  all  necessary  documentation of  the air
       quality  simulation modeling technique(s) and  computer
       codes judged  acceptable by  the Work-group are  publicly
       available,  including  user guides and other necessary
       guidance;

       Mutually conduct  the necessary activities, to  support
       rulemaking,   that  will  enable  the  adoption  of the
       acceptable air quality simulation modeling technique(s)
       in EPA's Guideline on Air Quality Models  (Revised'):

       Mutually conduct  training sessions on  the use of the
       accepted modeling technique(s);

       Submit   an   annual   report   of    its   activities,
       recommendations,  and plans for the  following year  to
       each organization signing this agreement.
Article IV.


Article V.


Article VI.
This MOU will remain in effect for five years from the date of
signature, at which time it will be reviewed.

This MOU does not create any enforceable rights or obligations
upon or in favor of any person or entity.

Key Officials
Key officials  (technical  personnel)  representing  each  agency
are as follows:
                                        13

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               National  Park Service
                      Mark Scruggs
                      National Park Service - AIR
                      P. 0.  Box 25287
                      Denver, Colorado  80225-0287

                      John Vimont
                      National Park Service - AIR
                      P. 0.  Box 25287
                      Denver, Colorado  80225-0287

               U.  S.  Environmental  Protection Agency
                      James Dicke
                      USEPA, OAQPS  (MD-14)
                      Research Triangle Park, NC 27711

                      Jason Ching
                      USEPA, AREAL  (MD-80)
                      Research Triangle Park, NC 27711

                      Alan Cimorelli
                      USEPA, Region 3  (3AM12)
                      841 Chestnut  Street
                      Philadelphia,  PA  19107

               U.  S.  Forest  Service
                      Richard W.  Fisher
                      WO/WSA
                      USDA Forest Service
                      240 W. Prospect
                      Fort Collins,  CO  80526

               U.  S.  Fish and Wildlife  Service
                      Bud Rolofson
                      National Park Service - AIR
                      P. 0.  Box 25287
                      Denver, Colorado  80225-0287

Article VII.   Termination:     Any   of  the   parties   may  terminate  their
               involvement  in  this  agreement  by providing  60  day written
               notice to the other parties.

Article VIII.  Nothing in this MOU  impairs  or in any vay affects the Federal
               Land   Manager's  authority   to   utilize  alternate  modeling
               techniques not agreed on by the parties herein,  in order to
               determine whether a proposed major emitting facility will have
               an  adverse impact  on air quality related values in accordance
               with  Section 165(d)  of the Clean Air Act (42 U.S.C. 7475(d)).
               Nor does  anything  in this MOU affect or impair the EPA's role
               in  implementing the PSD provisions of the Clean Air Act.  Each
               party also  reserves its right  to  submit  comments on  any
               rulemaking or proposal  in which  modeling  techniques  are
               selected  or recommended.


                                        14

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Article IX.
       During  the performance  of this  agreement,  the  participants
       agree to  abide  by the terras of Executive Order 11246  on non-
       discrimination  and will not  discriminate  against any person
       because of race, color, religion, sex or national  origin.  The
       participants  will  take  affirmative  action  to  ensure  that
       applicants are  employed without regard to their  race, color,
       religion, sex or national origin.

       No member or  delegate to Congress, or  resident Commissioner,
       shall be admitted to any share or part of this agreement, or to
       any benefit that may arise therefrom,  but this provision shall
       not be  construed to extend to this  agreement if made with a
       corporation for its general benefit.
                      2 0 NO V 1991
National Park Service
                                                                           '  '2  199)
                                           U.S.AEn^ironmental Protection^
                                                   '  mcy
       U.S. Forest Service   \
                                                                          1 ^ f-'T'
                                                                          4. 0 I\J h
                                    U.S. Fish and Wildlife Service
                                       15

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                           APPENDIX  B
                  LISTING OF WORKGROUP MEMBERS

Group Chairman
Mark Scruggs
National Park Service - AIR
P. O. Box 25287
Denver, Colorado 80225-0287

National Park Service
John Vimont
National Park Service - AIR
P. O. Box 25287
Denver, Colorado 80225-0287

U. s. Environmental Protection Agency
James Dicke1
USEPA, OAQPS (MD-14)
Research Triangle Park, NC 27711

Jason Ching1
USEPA, AREAL (MD-80)
Research Triangle Park, NC 27711

Alan Cimorelli
USEPA, Region 3 (3AM12)
841 Chestnut Street
Philadelphia, PA 19107

John Irwin1
USEPA, OAQPS (MD-14)
Research Triangle Park, NC 27711

U. S. Forest Service
Richard W. Fisher
WO/WSA
USDA Forest Service
240 W. Prospect
Fort Collins, CO 80526

U. S. Fish and Wildlife Service
Bud Rolofson
National Park Service - AIR
P. O. Box 25287
Denver, Colorado 80225-0287
1  On assignment from the National Oceanic and Atmospheric
Administration, U.S. Department of Commerce.
                                16

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i TtCHWCAL HEHOK"; DAI A
/Piijse mru Ir.s;r.ictio>is on the re.ers^ -.tyo/v <.v -.- -. .-.•:>•
1 REPORT NO J2.
EPA-454/R-92-001 |
4. TITLE ANDSUBTITLE
Interagency Workgroup on Air Quality Modeli
Work Plan Rationale
7. AUTHOR(S)
John S. Irwin
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Office of Air Quality Planning and Standarc
Technical Support Division
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
12. SPONSORING AGENCY NAME AND ADDRESS
3 = EC1P'ENT'S ACCESSION NO.
|5 REPORT DATE
m l-naartn i ^ 1992

-iJV) \j.n»^-i/ jg PERFORMING ORGANIZATION CODE
(8 PERFORMING ORGANIZATION REPORT NC.
i
i
|10. PROGRAM ELEMENT NO.
is !
11. CONTRACT/GRANT NO.
113. TYPE OF REPORT AND PERIOD COVERED
i
'14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This document presents a status report and workplan rationale for the operation of
the Interagency Workgroup on Air Quality Modeling (IWAQM) . The workgroup was formed
to provide a focus for development of technically sound regional air quality models
for regulatory assessments of pollutant source impacts on Federal class I areas.
This paper was published in an effort to inform the sponsoring Agencies and other
interested parties out IWAQM activities.
17. KEY WORDS AND DOCUMENT ANALYS.S
a. DESCRIPTORS
Air Pollution
Meteorology
Air Quality Dispersion Model
Visibility
Aerosols
18. DISTRIBUTION STATEMENT
Release Unlimited
b.lOENTIFIERS/OPES ENDED TERMS
New Source Review
Air Pollution Control
19. SECURITY CLASS This Report)
Unclassified
20. SECURtTv CLASS This pert)
Unclassified
c. COSATl Field 'Group

21. NO. OF PAGES
23
22. PRICE
EPA Form 2220-1 (Rev. 4-77)
                               PREVIOUS EOITION S OBSOLETE

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