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Contents
Page
ABSTRACT 1
1. INTRODUCTION 2-7
REFERENCES FOR INTRODUCTION 7-10
2. SAI 1973 MODEL 10-14
3. SAI 1976 MODEL 15-19
4. NEXUS/P MODEL 19-22
5. SULFA3D MODEL 23-27
6. LIRAQ-1 MODEL 27-31
7. LIRAQ-2 MODEL 32-36
8. SHIR-SHIEH MODEL 37-40
9. MESODIF MODEL 41-44
10. ELIASSEN-SALTBONES ONE-LAYER MODEL 44-47
11. ELIASSEN-SALTBONES TWO-LAYER MODEL 48-51
12. WENDELL-POVIELL-DRAKE MODEL 51-54
13. HEFfTER-TAYLOR-FERBER LONG-TERM MODEL 55-58
14. HEFFTER-TAYLOR-FERBER SHORT-TERM MODEL 59-62
15. SHEIH-MOROZ MODEL 62-66
16. SHEIH PUFF-GRID MODEL 66-69
17. BNL MODEL 70-74
18. STRAM MODEL 74-78
111
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ABSTRACT
A review of available long-range air quality transport
and diffusion models has been prepared under NOAA
contract 03-6-022-35254, to select, modify and apply
such a model for the simulation of air quality impact
associated with emissions from new energy resource
development in the Four Corners area of the Western
United States. Primary emphasis has been placed upon
the review of models that are presently operational and
currently available for use and adaptation.
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A REVIEW OF REGIONAL-SCALE AIR
QUALITY MODELS FOR LONG DISTANCE DISPERSION-
MODELING IN THE FOUR CORNERS REGION
1. INTRODUCTION
This document presents a review (ca. April 1977) of
available air quality simulation models that are appropriate to
long-range transport (e.g., 100-1000 km) of atmospheric
pollutants. This review has been prepared as part of a.
contractual effort by Environmental Research & Technology, Inc.
under NOAA contract 03-6-022-35254 to select, modify and apply
long-range atmospheric transport and diffusion models suitable to
the simulation of air quality impact associated with emissions
from new energy resource development (power generation, coal
gasification, oil shale processing) in the Four Corners Area of
the Western United States. In this effort, primary emphasis has
been placed upon the review of models that are already
operational, and that are, in principle, currently available for
use and adaptation outside the originating organization. A number
of additional constraints were used to select models for review.
These included the relative ease and costs of modification for
use in the Four Corners area, the computer implementation
restrictions, the computational, data and technical resources
required for program utilization, the flexibility for
multiple-scenario exercise to address both short-term and
long-term ambient air quality issues, etc.
This report is certainly not exhaustive;
include, for example, some very recent
particle-in-cel1 modeling methods. It does
conscientious effort, within limited resources
it does not
advances in
represent a
to assess the
current operational status and availability of long-range
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transport models, and their potential suitability for application
to the Four Corners Area under the specific requirements of the
study contract.
To facilitate the description and intercomparison of the
various models, a 'model characteristics' outline form of
presentation has been used, somewhat similar to that used in the
Argonne National Laboratories "Description of Air Quality Models
and Abstracts of Reference Materials" prepared for the February,
1977 Specialists Conference on the EPA Modeling Guidelines. The
characteristics used to describe the models fall into three major
divisions, e.g., (a) functional criteria, (b) usage criteria, and
(c) operational criteria. Each of these general divisions is
subdivided further.
The remainder of this introductory section presents an
overview of the two main types of models considered, e.g., grid
models and trajectory models. In succeeding sections each of
these models is in turn abstracted and outlined by
characteristics.
Models suitable for regional scale air quality simulation
studies can be divided into two general groups:
o grid models which numerically integrate the species
continuity equation, and
o trajectory models which numerically integrate the
horizontal advective terms and treat the diffusive
terms by algebraic technique.
Grid models have the potential to provide for accurate
simulation of nonlinear chemistry, horizontal advection, vertical
diffusion, wet and dry removal, and deposition processes. They
are inherently well suited to accomodate space and time
variations in meteorology and emission inventories. In addition,
for several grid models, there is a substantial body of
validating literature. (For discussion of the advantages and
disadvantages of grid models, see, for example, Sheih [1], Sheih
and Moroz [2], Shir and Shieh [3], and Liu and Durran [U].)
There are several well-known problems inherent in grid
models. Chief among these is the phenomenon called numerical
pseudo-diffusion, (see Molenkamp [5], Shieh [6], and Egan and
Mahoney [7]). Most common numerical approaches exhibit this
phenomenon to some degree, but techniques have been developed
(Egan and Mahoney [73, Boris and Book [8], and Long and Pepper
[29]) to overcome this difficulty.
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Given that numerical pseudo-diffusion can be minimized or
eliminated, another inherent problem with grid models lies in
their ability to properly treat subgrid-scale phenomenon. As
discussed in Sheih [1], the typical grid scale for a regional
model is of the order of 10 kilometers. Thus, emission sources
are modeled as, typically, 100 square kilometer area sources.
This is appropriate for distributed emission sources, but for
point sources this modeling procedure leads to premature dilution
of several orders of magnitude, and there is a corresponding
tendency to underestimate concentrations in the near vicinity of
point sources.
Beyond these problems, the criteria for numerical stability
of the integration techniques often require time steps which are
small compared to the computational costs of each time step.
While for short-term simulations (up to, say, 24 hours) the total
cost may not be excessive, the cost of projecting seasonal or
annual averages, assuming the model can do so, rapidly becomes
prohibitive. Because of these problems, several groups have
developed trajectory models which numerically treat horizontal
advection (the dominant phenomenon on the regional scale) and
treat the diffusive phenomena by a variety of well-known analytic
approximations. These trajectory models avoid the problems
associated with numerical pseudo-diffusion, are inherently
capable of dealing with subgrid-scale phenomena, and generally
cost relatively little for each The interence from [6] is that
time step so that long-term simulations are feasible. (See Sheih
[1], [6], or Start and Wendell [9].)
However, trajectory models generally assume that the total
concentration field of a pollutant is obtained by superposition
of the concentration fields for each source. This linear
superposition principle precludes an accurate treatment of
nonlinear chemistry. This limitation is a problem in terms of the
ability to incorporate future developments in the modeling of
nonlinear chemistry. Trajectory models also tend to require large
computer storage, although they are computationally cheaper than
grid models. Finally, while several groups have done validation
studies using trajectory models for long-term averages, little
has been done in the area of short-term averages.
Recently, Sheih [1] has proposed a model which uses the
trajectory approach until such time as the concentration field
has grown to grid-scale dimensions and then treats further
diffusion and advection by a grid mode. This interesting hybrid
of a trajectory and grid model could well prove the most accurate
approach to regional scale modeling. But, as a developmental
model, it has not yet been subjected to extensive validation.
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TRAJECTORY MODELS
One class of trajectory models uses the particle-in-cell
(PIC) approach to model regional dispersion of pollutants.
Originally developed by Harlow for fluid dynamical problems, this
approach was modified by Sklarew et al. [10] to apply to air
pollution simulations. In this approach, it is assumed that
pollutant concentrations can be adequately represented by
particles of various "weights". Dispersion is represented by the
movement of individual particles throughout the grid system,
while the "weight" of each particle is altered as chemical
reactions occur. Eliassen and Saltbones [11] use this PIC
approach to model S02 and SO1! transport over Europe. In their
model dry deposition is included through the deposition velocity
approach. Topography is not modeled explicitly, as is generally
true for the trajectory models discussed in this section, but
could be implicitly included through specification of the wind
field and spatial variation of the mixing depth. Eliassen and
Saltbones generalize this one-layer model to a two-layer model
[12] capable of exhibiting a vertical concentration gradient, but
with associated computational cost penalties.
The major practical drawback of these PIC models lies in the
large number of particles that must be tracked to achieve
realistic simulations. Large numbers of particles imply both
large storage requirements and long execution times (See [4] for
further discussions.)
Another class of trajectory models simulate source emissions
as time series of puffs or plume segments. The concentration
distribution within each puff is assumed to be Gaussian, with
standard deviations taken to be power-law functions of travel
distance. Trajectory-puff models have been developed by Lamb
[13], Roberts et al. [14], and others. Recently, Start and
Wendell [9] have developed a trajectory-puff model, MESODIF , to
study dispersion effects on regional scales. The initial version
of their model does not consider plume -rise, spatially variable
stability and mixing heights, topography, wet or dry removal
processes, linear sulfur chemistry, nor does it allow for
multisource configurations. Extensions to include topography,
multiple sources, and modifications to the time history of
Gaussian diffusion coefficients are not difficult. Perhaps the
most attractive feature of MESODIF is its relative simplicity,
which allows for easy installation, modification, checkout, and
quality control. Moreover, MESODIF requires only modest storage
and computational time. It also lends itself readily to effective
graphical visualizations of trajectories and concentration
fields.
One critical assumption in the MESODIF model is the
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inclusion of a horizontally isotropic Gaussian diffusion. Thus,
puffs are allowed to diffuse both in the crosswind and
longitudinal directions at equal rates. Heffter et al . avoided
this assumption with a plume segment model. This model assumes
the emission source to be a sequence of slices diffusing
vertically and crosswind by the Gaussian formula. The model was
modified by Meyers and Cederwall [17] at Brookhaven National
Laboratory to include both linear sulfur chemistry and removal
processes. Wendell et. al [15], and Hales et. al [30] have also
used the plume segment approach in their model. This conceptual
improvement as well as their capability for displaying plume
trajectories make them attractive alternatives to MESODIF.
More sophisticated trajectory models have been developed by
Sheih and Moroz [2] and Sheih [6]. In their most sophisticated
model, the plume from a continuous source is treated as a series
of puffs; each puff is represented by a set of six tracer
particles, which determine its size, shape, and location. At each
time step, the particles are moved to take into account
advection, eddy diffusion, wind shear, and buoyancy entrainment.
The concentration distribution of each puff is determined by
fitting an ellipsoid to the cluster of particles, with the
lengths of the principal axes taken to be standard deviations of
a Gaussian distribution. Since a copy of Sheih's model program
code is not available for evaluation at this time, its
operational requirements cannot be accurately assesses at
present. The inference from [6] is that the model may be
expensive in time and storage requirements; moreover, it has yet
to be demonstrated that the additional complexity offers
significant advantages in the accuracy of concentration
predictions for an air quality model appropriate to the Four
Corners Area.
GRID MODELS
In the grid model discussed in this section, time and space
derivatives are replaced by finite difference expressions.
Inherent in many finite difference approximations is a type of
numerical error called pseudo-diffusion. This numerical diffusion
is typically much larger than atmospheric turbulent diffusion.
(For more detailed discussion, see [5] or [6].) It is, therefore,
very important to use finite difference techniques which minimize
or eliminate numerical diffusion.
In the model developed by Shir and Shieh [18] to study S02
transport in the St. Louis region, the horizontal advection terms
are approximated by an explicit, second-order, centered finite
difference technique, while the vertical diffusion term is
integrated by an implicit Crank-Nicholson method. A similar
scheme is used in the model developed by SAI [19]. Both of these
techniques are afflicted with numerical pseudo-diffusion which
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seriously limit duration of simulations (see, for example, Liu
and Seinfeld [20]). The SAI model is, additionally, extremely
costly to run. It is presently being upgraded to eliminate
numerical diffusion by use of the SHASTA method of Boris and Book
[8]. As of this date, however, the new version of their model has
not been released.
Another model using the SHASTA method is the LIRAQ model
developed at Lawrence Livermore Laboratory [21]. This model,
numerically integrates a vertically averaged concentration
equation and can treat reactive chemical species. The LIRAQ model
has only recently been developed and remains to be validated. It
would require extensive modifications for application to the Four
Corners Area. It is not capable of implementation except on a
CDC-7600 system.
An alternate method for eliminating numerical diffusion was
developed by Egan and Mahoney [7]. This second-moment method not
only eliminates the pseudo-diffusion but can be modified to allow
consideration of subgrid-scale sources. The Egan-Mahoney method
was used by Rao et al. ([22], [23]) to develop a regional-scale
advective-diffusive model for the Sulfate Regional Experiment
(SURE). This model, SULFA3D, has the flexibility to incorporate
vertically variable inputs such as wind and turbulent diffusivity
profiles, and observed mixing depth data. Further, linear
chemical transformation and removal processes can be modeled as
indicated in [22] or [23].
ACKNOWLEDGMENTS
This study was performed for NOAA under an interagency
agreement with the Office of Energy, Minerals and Industry,
Office of Research and Developmen t, EPA. We acknowledge with
thanks the guidance and helpful suggestions of Herbert J.
Viebrock, Meteorology Laboratory (EPA/NOAA) -ARL, and Dr. John
Bowen, (EPA/EMSL)-Las Vegas.
REFERENCES FOR INTRODUCTION
1. C. M. Sheih, "A Puff-Grid Model for Predicting Pollutant
Transport Over an Urban Area", (1976) to appear in APCA.
2. C. H. Sheih and W. V. Moroz, "A Lagrangian Puff Diffusion
Model for the Prediction of Pollutant Concentration Over
Urban Areas", Proc. Third International Clean Air Congress,
B43-B52, (1973).
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3. C. C. Shir and L. J. Shieh, "A Generalized Urban Air Pollution
Model and Its Application to the Study of S02 Distributions
in the St. Louis Metropolitan Area", JAM, Vol. 13, pp.
185-224, (1974).
4. M. K. Liu and D. Durran, "On the Modeling of Transport and
Diffusion of Air Pollutants Over Long Distances", SAI
Interim Report ER76-55, EPA Contract 68-01-3591, (1976).
5. C. R. Molenkamp, "Accuracy of Finite-Difference Methods
Applied to the Advection Equation", JAM Vol. 7, pp. 160-167,
(1968).
6. C. M. Sheih, "A Lagrangian Puff Diffusion Model with Wind
Shear and Dynamic Plume Rise", (1973), submitted to Atmos.
Env.
7. B. A. Egan and J. R. Mahoney, "Numerical Modeling of Advection
and Diffusion of Urban Area Source Pollutants", JAM, Vol.
11, pp. 312- 322, (1972) .
8. J. P. Boris and D. L. Book, "Flux-Corrected Transport 1:
SHASTA, A Fluid Transport Algorithm That Works", J. Comp.
Physics, Vol. 11, pp. 38-69, (1973).
9. G. E. Start and L. L. Wendell, "Regional Effluent Dispersion
Calculations Considering Spatial and Temporal Meteorological
Variables", NOAA Tech. Memo. ERL-ARL-44, (1974).
10. R. C. Sklarew, A. J. Fabrick, and J. E. Prager, "A
Particle-In-Cell Method for the Numerical Solution of the
Atmospheric Diffusion Equation, and Applications to Air
Pollution Problems -- Final Report", EPA Contract Number
68-02-0006, (1971).
11. A. Eliassen and J. Saltbones, ^'Sulfur Transport and Dry
Deposition Over Europe Described By A Simple Lagrangian
Dispersion Model", Norwegian Institute For Air Research,
(1976).
12. A. Eliassen and J. Saltbones, "A Two-Layer Dispersion Model:
Description and a Few Results", Norwegian Institute for Air
Research, (1975).
13. R. G. Lamb, "An Air Pollution Model of Los Angeles", (1969),
Master's Thesis, UCLA.
14. J. J. Roberts, E. S. Croke, and A. S. Kennedy, "An Urban
Atmospheric Dispersion Model", Proc. of Symposium on
Multiple-Source Urban Diffusion Models, Air Poll. Conf. Off.
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Publication No. AP-86, 6.1-6.72, (1970).
15. L. L. Wendell, D. G. Powell, and R. L. Drake, "A Regional
Scale Model For Computing Deposition and Ground Level Air
Concentration of S02 and Sulfates from Elevated and Ground
Sources", Proceedings of the Third Symposium on Atmospheric
Turbulence and Air Quality, pp. 318-324, (1976).
16. J. L. Heffter, A. D. Taylor, G. J. Ferber, "A
Regional-Continental Scale Transport, Diffusion, and
Deposition Model", NOAA Technical Memorandum ERL AR-50,
(1975) .
17. R. E. Meyers and R. T. Cederwall, "Fossil Pollutant Transport
Model Development", BNL RESP Annual Report, BNL 50478, pp.
46-61, (1975).
18. C. C. Shir and L. J. Sheih, "A Generalized Urban Air
Pollution Model and Its Application to the Study of the S02
Distribution in the St. Louis Metropolitan Area", JAM, Vol.
13, PP. 185-204, (1974).
19. S. D. Reynolds, P. M. Roth, and J. H. Seinfeld, "Mathematical
Modeling of Photochemical Air Pollution -I: Formulation of
the Model", Atmos. Env. Vol. 7, pp. 1033-1061, (1973).
20. M. K. Liu and J. H. Seinfeld, "On the Validity of Grid and
Trajectory Models of Urban Air Pollution", Atmos. Env., Vol.
9, pp. 555-574, (1975).
21. M. C. MacCracken and G. D. Sauter, ed., "Development of an
Air Pollution model for the San Francisco Bay Area" , Final
Report to NSF, UCRL-51920, Lawrence Livermore Lab.,
Livermore, CA (1975).
22. K. S. Rao, I. Thomson, and B. A. Egan, "Regional Transport
Model of Atmospheric Sulfates", 69th Annual Meeting of the
Air Pollution Control Association, Portland, Oregon, (1976).
23. G. M. Hidy, E. Y. Tong, and P. K. Mueller, "Design of the
Sulfate Regional Experiment (SURE)", EPRI-EC-125, Vol. 1,
Electric Power Research Institute, Palo Alto, California
(1976).
24. M. H. Dickerson, "MASCON-A Mass Consistent Atmospheric Flux
Model for Regions With Complex Terrain", submitted to JAM,
(1976) .
25. Y. Sasaki, "An Objective Analysis Based on the Variational
Method", J. Meteor. Soc. Japan, Vol. 36, pp. 77-78, (1958).
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26. Y. Saski, "Some Basic Formalisms in Numerical Variational
Analysis", Mon. Wea. Rev, Vol. 98, pp. 875-883, (1970).
27. Y. Sasaki, "Numerical Variational Analysis Formulated Under
the constraints Determined by Longwave Equation and Low-Pass
Filter", Mon. Wea. Rev., Vol. 98, pp. 884-898, (1970).
28. C. Y. Liu and W. R. Goodin, "An Iterative Algorithm for
Objective Wind Field Analysis", Mon. Wea. Rev., Vol. 104,
pp. 784-792, (1975).
29. P. E. Long and D. W. Pepper, "A Comparison of Six Numerical
Schemes for Calculating the Advection of Atmospheric
Pollution", Proc. Third Symposium on Atmospheric Turbulence
and Air Quality, (1976).
30. Hales, J. M., Powell, D. C., and T. D. Fox, "STRAM-An Air
Pollution Model Incorporating Non-Linear Chemistry, Variable
Trajectories and Plume Segment Diffusion". EPA-450/3-77-012,
(1977) .
2. SAI 1973 MODEL
This model performs a numerical integration of the species
conservation equation. A fractional steps technique is used to
subdivide the governing equation into three independent steps in
the 3 spatial directions. The horizontal dimensions are solved
explicitly using a mass conservative finite difference scheme
devised by Price, Varga, and Warren [1966], while the vertical
direction is solved implicitly using a Crank-Nicholson algorithm.
The kinetic mechanism is embedded in the vertical integration.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? No.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? No.
SPATIAL EXTRAPOLATION TECHNIQUE? None.
(Input wind field at each grid point.)
INPUT TIME INTERVAL? Hourly.
DIVERGENCE FREE? No.
SMOOTHING? Manually.
ADJUSTED FOR MIXING LID? Implicit.
10
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MIXING LID:
INPUT SPATIAL REQUIREMENT? At each grid point.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Diffusivity
INPUT SPATIAL REQUIREMENT? Horizontal K spatially
uniform. Vertical K at grid points.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
OTHER METEOROLOGICAL DATA? Radiation Intensity.
EMISSIONS:
SOURCE
INVENTORY
cells.
Species concentrations, ground level
ELEVATED SOURCES? No.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? Yes
INSTANTANEOUS SOURCE EMISSIONS? Yes.
PLUMS RISE? No
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN? Implicit through windfield and mixing lid
Explicitly treated in transport equations
WIND FIELD ADJUSTED FOR TERRAIN?
MIXING LID ADJUSTED FOR TERRAIN?
VARIABLE RECEPTOR HEIGHTS? No.
VARIABLE SOURCE HEIGHTS? No.
Yes
Yes
TRANSPORT:
ADVECT1VE METHOD?
DIFFUSIVE METHOD?
Both advection and diffusion
numerical integration of the species
are modeled by
mass conservation
1 1
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equation. The 4 dimensional equations are integrated by
the method of fractional steps described by Yanenko [1971],
The horizontal integrations use an explicit second order
method developed by Price et al. [1966]. The vertical
integration uses an implicit Crank-Nicolson method
to avert stability problems that might arise in the
treatment of diffusion when the grid spacing is small
due to a shallow mixing lid.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? Yes, dominating results after 24 hours.
SPATIAL RESOLUTION AND EXTENT OF MESH?
25 by 25 by 5 grid with approximate horizontal
resolution of 2 miles.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Four minute time increment, with 24 hour time
extent.
BOUNDARY CONDITIONS?
Boundary conditions are imposed on the vertical
and horizontal sides of the 3 dimensional modeling region.
At the surface, the mass flux of each species is specified
At the mixing lid, the boundary condition states that the
normal component of the mass flux is continuous across the
boundary when material is transported into the modeling
region from above the inversion base. When material is
transported in the other direction, the flux is set equal
to 0 to reflect the abrupt change in stability associated
with an inversion layer.
On the horizontal sides, the boundary conditions
express the continuity of mass flux when flow is directed
into the region. For flow out of the region, the diffusive
component of the total flux is set equal to 0.
INITIAL CONDITIONS?
Initial conditions are specified by giving the
species concentrations for each grid cell. The surface
cells are assigned values based on the source inventory,
and these concentrations are-assumed to be vertically
un iform.
NUMBER OF VERTICAL LAYERS? 5
BACKGROUND DATA? Within the modeled region, all sources
included in the source inventory. There is no pro-
vision to include transport of material into the
region from exterior sources.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? NOx Ox HNOx COx HOx ROx HC
WHICH NON-REACTIVE SPECIES? None.
12
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DEPOSITION? Yes.
WET? No.
DRY? Yes.
DECAY? No.
CHEMISTRY? Yes.
LINEAR? No.
NONLINEAR? Yes.
WHAT CHEMICAL SYSTEM?
31 steps for the NOx-HC-03 system.
Seinfeld et al [1971], Hecht and Seinfeld [1972].
COMPUTED DATA:
AVERAGING PERIODS? Short term only (run duration)
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Yes.
3 HOUR? Yes (run duration).
24 HOUR? Yes (run duration).
VALIDATION HISTORY?
The SAI model has been validated by comparing predicted
results with data taken in the Los Angeles Basin in September,
1969> and favorable agreement has been obtained.
APPLICABLE TO FOUR CORNERS REGION?
As a short-range (urban scale) photochemical smog
model for the Los Angeles air basin, the validation studies
have little applicability to the regional Four Corners
problem, with its significantly different chemistry.
INCORPORATION OF OBSERVED DATA? No.
CALIBRATION POTENTIAL? Dependent on existence of observed
data for each species in the Four Corners Region.
USAGE CRITERIA:
USER'S MANUAL? Yes.
AVAILABILITY OF THE MODEL? In the public domain.
EASE OF MODIFYING MODEL? Very difficult unless intimately familiar
with code.
EASE OF USING MODEL? Requires skilled interpretation.
VOLUME OF DATA REQUIRING MANUAL PREPARATION?
There is a large volume of input data required for
each model run. The data includes the gridded windfield for each
model hour, the inversion lid heights, the turbulent diffusivities
and emission rate for each species, for each grid point and hour.
In addition, there is a large labor investment in preparing
an exhaustive source inventory for each species to accurately
assess the initial species concentration in each grid cell.
13
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EASE OF MODEL INSTALLATION ON UNIVAC? Has been implemented.
EASE OF MODEL MAINTENANCE? Difficult.
OUTPUT INTERPRETATION REQUIREMENTS? No unusual requirements.
OPERATION:
CORE REQUIREMENTS? Less than 128K.
COMPUTATIONAL TIME REQUIREMENTS? A 10 hour simulation for
non-reactive hydrocarbons takes 2 min., reactive 26.5 min,
INPUT DATA PREPARATION TIME REQUIREMENTS? Substantial.
REFERENCES FOR SAI 1973 MODEL:
M.K. Liu, D. C. Whitney, J. H. Seinfeld, P. M. Roth, 1976,
"Continued Research in Mesoscale Air Pollution Simulation
Modeling", EPA 600/4-76-016
S. D. Reynolds, P.M. Roth, and John Seinfeld , 1974,
"Mathematical Modeling of Photochemical Air Pollution - III
Evaluation of the Model", Atmos. Env. Vol. 8 pp 563-596
S. D. Reynolds, P.M. Roth, and John Seinfeld , 1974,
"Mathematical Modeling of Photochemical Air Pollution - II
A Model and Inventory of Pollutant Emissions"
Atmos. Env. Vol 8 pp 97-130
S. D. Reynolds, P.M. Roth, and John Seinfeld , 1973,
"Mathematical Modeling of Photochemical Air Pollution - I
Formulation of the Model" Atmos. Env. Vol 7,pp 1033-1061
Hecht T.A. and Seinfeld J.H., 1972, "Development and
Validation of a. Generalized Mechanism for Photochemical Smog",
Environ. Sci. Technol . Vol 6,p 4?
Seinfeld J. H.,Hecht T. A. and Roth P.M., 1971, "A Kinetic
Mechanism for Atmospheric Photochemical Reactions",
Report 71SAI-9, Systems Applications, Inc.
Yanenko.N N, 1971, "Method of Fractional Steps: The Solution of
Problems of Mathematical Physics in Several Variables",Eng. Trans
by M. Holt, Springer-Verlag.N.Y.,N.Y.
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3. SAI 1976 MODEL
The SAI 1976 model is the result of efforts to upgrade the
1973 model (see Section 2). These efforts are purported to have
resulted in
> The implementation of improved treatments of atmospheric
transport and chemical reaction processes,
> The development of microscale modeling capabilities,
> The parameterization and incorporation of pollutant uptake
processes,
> The refinement of numerical integration procedures, and
> The development of aerosol modeling capabilities.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Yes.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? No.
SPATIAL EXTRAPOLATION TECHNIQUE? None.
(Input wind field at each grid point.)
INPUT TIME INTERVAL? Hourly.
DIVERGENCE FREE? No.
SMOOTHING? Manually.
ADJUSTED FOR MIXING LID? Implicit.
MIXING LID:
INPUT SPATIAL REQUIREMENT? At each grid point.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Diffusivity.
INPUT SPATIAL REQUIREMENT? Horizontal K spatially
uniform. Vertical K at grid points.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
OTHER METEOROLOGICAL DATA? Radiation Intensity.
15
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EMISSIONS:
SOURCE INVENTORY: Species concentrations, ground level
cells .
ELEVATED SOURCES? No.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? Yes.
INSTANTANEOUS SOURCE EMISSIONS? Yes.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN? Implicit through windfield and mixing lid.
Explicitly treated in transport equations.
WIND FIELD ADJUSTED FOR TERRAIN? Yes.
MIXING LID ADJUSTED FOR TERRAIN? Yes.
VARIABLE RECEPTOR HEIGHTS? No.
VARIABLE SOURCE HEIGHTS? No.
TRANSPORT:
ADVECTIVE METHOD?
DIFFUSIVE METHOD?
Both advection and diffusion are modeled by
numerical integration of the species mass conservation
equation. The 4 dimensional equations are integrated by
the method of fractional steps described by Yanenko [1971].
The horizontal integrations use the SHASTA method of
Boris and Book [1973] to minimize pseudo-diffusion. The
vertical integration uses an implicit Crank-Nicolson method
to avert stability problems that might arise in the
treatment of diffusion when the grid spacing is small
due to a shallow mixing lid.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? Kept minimal.
SPATIAL RESOLUTION AND EXTENT OF MESH?
25 by 25 by 10 grid with approximate resolution
of 2 miles.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Four minute time increment, with 24 hour time
extent.
16
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BOUNDARY CONDITIONS?
Boundary conditions are imposed on the vertical
and horizontal sides of the 3 dimensional modeling region.
At the surface, the mass flux of each species is specified.
At the mixing lid, the boundary condition states that the
normal component of the mass flux is continous across the
boundary when material is transported into the modeling
region from above the inversion base. When material is
transported in the other direction, the flux is set equal
to 0 to reflect the abrubt change in stability associated
with an inversion layer.
On the horizontal sides, the boundary conditions
express the continuity of mass flux when flow is directed
into the region. For flow out of the region, the diffusive
component of the total flux is set equal to 0.
INITIAL CONDITIONS?
Initial conditions are specified by giving the
species concentrations for each grid cell. The surface
cells are assigned values based on the source inventory,
and these concentrations are assumed to be vertically
uniform.
NUMBER OF VERTICAL LAYERS? 10
BACKGROUND DATA? Within the modeled region, all sources
included in the source inventory. There is no pro-
vision to include transport of material into the
region from exterior sources.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? NOx Ox HNOx COx HxOx ROx HC
paraffins,olefins,aromatics,aldehydes,PAN,
S02, total aerosol mass concentration.
WHICH NON-REACTIVE SPECIES? None.
DEPOSITION? Yes.
WET? No.
DRY? Yes.
DECAY? No.
CHEMISTRY? Yes.
LINEAR? No
NONLINEAR? Yes.
WHAT CHEMICAL SYSTEM?
Whitten and Hogo [1976].
COMPUTED DATA:
AVERAGES? Short term only (run duration).
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
17
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1 HOUR? Yes
3 HOUR? Yes (run duration).
24 HOUR? Yes (run duration)
VALIDATION HISTORY?
None to date
INCORPORATION OF OBSERVED DATA? No.
CALIBRATION POTENTIAL? Dependent on existence of observed
data for each species in the Four Corners Region.
USAGE CRITERIA:
AVAILABILITY OF THE MODEL? Model exists in a developmental state
at this time.
EASE OF MODIFYING MODEL? Cannot be ascertained at this time.
EASE OF USING MODEL? Cannot be ascertained at this time.
VOLUME OF DATA REQUIRING MANUAL PREPARATION?
There is a large volume of input data required for
each model run. The data includes the gridded windfield for each
model hour, the inversion lid heights, the turbulent diffusivities
and emission rate for each species, for each grid point and hour.
In addition, there is a large labor investment in preparing
an exhaustive source inventory for each species to accurately
assess the initial species concentration in each grid cell.
EASE OF MODEL INSTALLATION ON UNIVAC? Cannot now be ascertained .
EASE OF MODEL MAINTENANCE? Cannot now be ascertained .
OUTPUT INTERPRETATION REQUIREMENTS? Cannot now be ascertained .
OPERATION:
CORE REQUIREMENTS? Cannot now be ascertained.
ON LINE STORAGE REQUIREMENTS? Cannot now be ascertained.
COMPUTATIONAL TIME REQUIREMENTS? Cannot now be ascertained.
INPUT DATA PREPARATION TIME REQUIREMENTS? Substantial.
OTHER HARD WARE REQUIREMENTS? Cannot now be ascertained.
REFERENCES FOR SAI 1976 MODEL:
All references for the SAI 1973 model, plus
Reynolds et al., 1976, "Continued Development and Validation
of a Second Generation Photochemical Air Quality
Simulation Model: Volume I --Refinements in the
Treatment of Meteorology, Chemistry, Pollutant
Removal Processes, and Numerical Analysis", Final Report
EPA Contract 68-02-2216
-------
G.Z. Whitten and H. Hogo, 1976, "Mathematical Modeling of
Simulated Photochemical Smog",Final Report,
EPA Contract 68-02-0580
M.K. Liu and Dale Durran, 1973, "On the Modeling of Transport and
Diffusion of Air Pollutants Over Long Distances"
Interim Report ER76-55, EPA Contract 68-01-3591
J.P. Boris and D.L.Book, 1973, "Flux Corrected Transport --I
"SHASTA, A Fluid Transport Algorithm That Works",
J.Comp.Phys. Vol 11, pp38-69
4. PIC NEXUS/P
NEXUS/P is one example of many particle-in-cell models. The
particle-in-cell models simulate pollutant emissions by particles
each of which accounts for a definite amount of pollutant. They
are advected in a Lagrangianly manner by a pseudo-velocity
contrived from local diffusion and advection velocity. The
pollutant concentration in each grid cell is given by the total
number of particles in the cell.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD: Particle in cell models can be used with
almost any routine which generates a suitable
gridded wind field.
VERTICAL RESOLUTION? No.
SINGLE STATION? No.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE? Yes.
INPUT TIME INTERVAL? Hourly.
DIVERGENCE FREE? No.
SMOOTHING? Yes.
MIXING LID:
INPUT SPATIAL REQUIREMENT? Spatially uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant in time.
TURBULENCE DATA:
19
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DIFFUSIVITY OR STABILITY? Diffusivity.
INPUT SPATIAL REQUIREMENT? Every cell.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT Hourly?
OTHER METEOROLOGICAL DATA? None
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? No.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? Yes.
INSTANTANEOUS SOURCE EMISSIONS? No?
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No
TERRAIN?
IMPLICIT or EXPLICIT? Implicit.
WIND FIELD ADJUSTED FOR TERRAIN? External to model
MIXING LID ADJUSTED FOR TERRAIN? External to model
VARIABLE RECEPTOR HEIGHTS? No.
VARIABLE SOURCE HEIGHTS? No.
TRANSPORT:
ADVECTIVE METHOD?
DIFFUSIVE METHOD?
Particles are advected in a Lagrangianly manner by a
pseudo-velocity contrived from local diffusion and
the advection velocity.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH? 22x21 cells,
resolution of 2 miles.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Five minutes is typical.
BOUNDARY CONDITIONS?
Impervious barrier at the ground with transmittive
sides and top. Inversion between 3rd and 4th
20
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layers limits upward diffusion. Particles which
penetrate past the middle of the fourth layer
are eliminated.
INITIAL CONDITIONS?
Initial vertical profile of the pollutant
concentration is assumed to be reduced by one
half every 100 meters.
NUMBER OF VERTICAL LAYERS? 4.
BACKGROUND DATA? Yes, supplied by user.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? NO, N02, 03, HC, and
HN02 with 0, R02, and OH in pseudo-equilibrium.
WHICH NON-REACTIVE SPECIES? None.
DEPOSITION? No.
DECAY? None.
CHEMISTRY? Yes.
LINEAR? No.
NON-LINEAR? Yes.
WHAT CHEMICAL SYSTEM? After Eschenroeder and
Martinez.
COMPUTED DATA:
AVERAGES? No, instantaneous concentrations.
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? No.
VALIDATION HISTORY? See Sklarew et al. [1971].
APPLICABLE TO FOUR CORNERS REGION?
NEXUS/P is not applicable in its present form.
However, a particle in cell model could be designed
for the region.
INCORPORATION OF OBSERVED DATA? Possible.
CALIBRATION POTENTIAL? Good if observed data are available.
USAGE CRITERIA:
USER'S MANUAL? No.
AVAILABILITY OF THE MODEL? In public domain
EASE OF MODIFYING MODEL? ???
EASE OF USING MODEL? ???
21
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VOLUME OF DATA REQUIRING MANUAL PREPARATION?
Source emissions, mean winds, and diffusivities
specified for each cell throughout the grid
during the time period being simulated.
ERROR DIAGNOSTICS? ???
EASE OF MODEL INSTALLATION ON UNIVAC? Easy
EASE OF MODEL MAINTENANCE? ???
OUTPUT INTERPRETATION REQUIREMENTS? ???
OPERATION:
CORE REQUIREMENTS? 230K for 2000 cells, 10000 particles and 5
species.
ON LINE STORAGE REQUIREMENTS? ???
COMPUTATIONAL TIME REQUIREMENTS? Extremely expensive: a 16 hour
simulation takes 1.5 hours on a
UNIVAC 1108.
INPUT DATA PREPARATION TIME REQUIREMENTS? Depends on the
given simulation.
OTHER HARDWARE REQUIREMENTS? ???
REFERENCES FOR NEXUS/P MODEL:
Sklarew,R.C. , 1970, 'A New Approach:The Grid Model of Urban
Air Pollution', APCA Paper No. 70-79 (June 1970),
Systems, Science and Software, La Jolla, Calif.
Sklarew, R.C. ,1970, 'Preliminary Report of the S3 Urban
Air Pollution Model Simulation of Carbon
Monoxide in Los Angeles',Systems, Science,
and Software Inc, La Jolla, Calif, p 2
Sklarew, R. C., A. J. Fabrick, and J. E. Prager, 1971:
A Particle-In-Cell Method for Numerical Solution
of the Atmospheric Diffusion Equation and
Applications to Air Pollution Problems (Volume 1).
Systems, Science, and Software, La Jolla, California.
Eschenroeder, A. Q. and Martinez,J.R., 1972, 'Mathe-
matical Modeling of Photochemical Smog',
General Research Corporation, Santa Barbara,
Calif.
22
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5. SULFA3D MODEL
SULFA3D is a quasi-Lagrangian model with linear chemistry
based on the Egan-Mahoney method of moments. The model accounts
for advective transport in the horizontal by the mean wind, and
for vertical diffusion. The air masses are advected and dispersed
each time step in the Lagrangian sense, and immediately
afterwards a mass decomposition to a stationary Eulerian grid is
performed. To accomplish the turbulent diffusion calculations,
the model has three air layers, each of uniform depth over the
grid region, in the vertical. For each grid cell in the
horizontal, emissions can be introduced into one of the three
layers depending on the effective release height for elevated
point sources. All ground-level point and area source emissions
are introduced into the lowest layer next to the ground. Thus,
this model is particularly suited to investigate, for example,
the effects of tall stacks in reducing the ambient concentration
levels of S02 and S04.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Yes.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE? None.
INPUT TIME INTERVAL? Every 12 hours.
TEMPORAL INTERPOLATION TECHNIQUE? Not at present.
DIVERGENCE FREE? Depends on specification of wind
field.
SMOOTHING? Manual.
ADJUSTED FOR MIXING LID? Yes.
MIXING LID: Uniform lid.
INPUT SPATIAL REQUIREMENT? Spatially uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? None.
TEMPORAL INTERPOLATION? Temporally uniform.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Vertical diffusivity
only .
INPUT SPATIAL REQUIREMENT? Three discrete values
of K are specified at the centers of the three
vertical layers.
23
-------
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Temporally uniform
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? No
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? Yes.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? No.
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN?
IMPLICIT OR EXPLICIT? Implicit (terrain following
coordinate system.)
WIND FIELD ADJUSTED FOR TERRAIN? External to model
MIXING LID ADJUSTED FOR TERRAIN? External to model
VARIABLE SOURCE HEIGHTS? Yes.
TRANSPORT:
ADVECTIVE METHOD?
The masses are advected and dispersed each time
step in the Lagrangian sense, and immediately afterwards
a mass decomposition to the stationary Eulerian grid is
preformed.
DIFFUSIVE METHOD?
The conservation of mass tracer equation is
solved using the Egan-Mahoney numerical method. Details
and discussion of this method can be found in Egan and
Mahoney [1972a,b] and Pedersen-Prahm [1971*].
HORIZONTAL DIFFUSION? No.
VERTICAL DIFFUSION? Yes, explicit.
PSEUDO-DIFFUSION? Minimal.
SPATIAL RESOLUTION AND EXTENT OF MESH? Default:
-------
26x17x3 with 80 km resolution. Variable vertical
resolution.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Time increment determined by the linear
advective and diffusive stability criteria:
U*(delta t/delta x) < 1
K*(delta t/H»»2) < 0.5
BOUNDARY CONDITIONS?
Upper boundary: complete reflection.
Lower boundary: complete or partial reflection.
INITIAL CONDITIONS? User specified.
NUMBER OF VERTICAL LAYERS? 3-
BACKGROUND DATA? Yes, user specified.
SPECIES:
MULTIPLE SPECIES?
WHICH REACTIVE SPECIES? S02, S04 only
WHICH NON-REACTIVE SPECIES? None, but could
be modified readily for any passive species.
DEPOSITION? Yes.
WET? Yes (with assumed precipitation rate).
DRY? Yes.
DECAY? No.
CHEMISTRY?
LINEAR? Yes.
NON-LINEAR? No.
WHAT CHEMICAL SYSTEM? Simple linear transformation
of S02 to S04.
COMPUTED DATA:
AVERAGES?
LONG TERMCANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Yes, if 1 hour run duration.
3 HOUR? Yes, if 3 hour run duration.
24 HOUR? Yes if 2M hour run duration.
VALIDATION HISTORY?
SULFA3D has been extensively exercised in the Northeastern
U.S., New York City, and Los Angeles area.
APPLICABLE TO FOUR CORNERS REGION? Yes, with modifications.
INCORPORATION OF OBSERVED DATA? Can be modified to
include observed data.
CALIBRATION POTENTIAL? Good.
25
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USAGE CRITERIA:
USER'S MANUAL? No.
AVAILABILITY OF THE MODEL? Not presently in public domain but
it is releasable.
EASE OF MODIFYING MODEL? Model written in highly modular fashion
readily modified.
EASE OF USING MODEL? Good, with documentation which is not
generally available at present.
VOLUME OF DATA REQUIRING MANUAL PREPARATION?
S02 emission rates must be specified in each
cell. Background concentrations of S02 and
S04 must be specified. Wind field data must
be determined (once every 12 hours).
ERROR DIAGNOSTICS? Minimal.
EASE OF MODEL INSTALLATION ON UNIVAC? Easily implemented.
EASE OF MODEL MAINTENANCE? Easily maintained.
OUTPUT INTERPRETATION REQUIREMENTS? Requires some meteorological
and sulfur chemistry background.
OPERATION:
CORE REQUIREMENTS? Moderate to high - a function of resolution
350K on IBM 360.
ON LINE STORAGE REQUIREMENTS? Moderate - a function of
COMPUTATIONAL TIME REQUIREMENTS? 5-15 minutes on IBM
A function of the resolution.
INPUT DATA PREPARATION TIME REQUIREMENTS? Substantial -
3-4 man-weeks of work.
OTHER HARD WARE REQUIREMENTS? None.
resolution
360.
REFERENCES FOR SULFA3D MODEL:
Design of the Sulfate Regional Experiment (SURE).
prepared by Environmental Research and Technology,
Inc. for Electric Power Research Institute. 1976.
EPRI document EC-125.
Egan.B.A. "Numerical Modeling of Urban Air Pollution Transport
Phenomena",Ph.D. Dissertation,Harvard School of Public Health,(1971)
Egan.B.A. and J. R. Mahoney, "Applications of a Numerical Air
Pollution Transport Model to Dispersion in The Atmospheric Boundry
Layer", J. Appl . Meteor. Vol 11, No. 7 pp 312-322 (1972)
Egan,B.A. and J.R. Mahoney, "Applications of a Numerical Air
Pollution Transport Model To Dispersion in The Atmospheric Boundry
26
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Layer",J.Appl. Meteor. Vol 11,No. 7, pp 1023-1039 (1972)
Pedersen, L. B. and Prahm, L. P., "A Method for Numerical
Solution of the Advection Equation", Tellus Vol 26,No. 5, pp 594-602
(197M)
6. LIRAQ-1 MODEL
LIRAQ is a very large regional-scale air quality
simulation model developed by Lawrence Livermore Laboratory to
predict the spatial and temporal variations in the concentrations
of the most significant photochemically reactive and non-reactive
air pollutants throughout the San Francisco Bay Area. LIRAQ-1 is
the non-reactive version. It takes into explicit account the
complex topography, meteorology, and source inventory of the Bay
Area. LIRAQ-1 is implementable at present only on a CDC-7600 and
specifically implemented only at the Lawrence Livermore
Laboratory and the Lawrence Berkeley Laboratory.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
LIRAQ uses the mass consistent wind fields
generated by the MASCON program (Dickerson,1973;
Sherman,1975)
VERTICAL RESOLUTION? No, vertical wind
profile assumed; model uses vertically
integrated layer.
GRIDDED INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
Missing data is interpolated or
extrapolated manually on the basis
of expert meteorological judgement
or prior experience.
INPUT TIME INTERVAL? Every three hours.
DIVERGENCE FREE? Yes.
ADJUSTED FOR MIXING LID? Yes, explicitly.
MIXING LID:
27
-------
INPUT SPATIAL REQUIREMENT?
For as many grid points as are
available or are needed to define
the meteorological structure.
SPATIAL EXTRAPOLATION? Same as wind field.
INPUT TEMPORAL REQUIREMENT? Every three hours.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Diffusivity.
INPUT SPATIAL REQUIREMENT? None, K is
calculated internally.
SPATIAL EXTRAPOLATION? ???
INPUT TEMPORAL REQUIREMENT? None.
OTHER METEOROLOGICAL DATA? Yes, but external to program
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? Yes.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? No.
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN?
IMPLICIT OR EXPLICIT? Explicit in the wind field.
WIND FIELD ADJUSTED FOR TERRAIN? Yes.
MIXING LID ADJUSTED FOR TERRAIN? Yes.
VARIABLE RECEPTOR HEIGHTS? Yes.
VARIABLE SOURCE HEIGHTS? Yes,but of little benefit since
since sources are vertically averaged in a layer,
TRANSPORT:
ADVECTIVE METHOD?
LIRAQ-1 uses the SHASTA method of Boris and
Book [1973] to minimize psuedo-diffusion in the
horizontal advection. This method takes into account
28
-------
the integrated mass flux and variable inversion
height properties.
DIFFUSIVE METHOD?
LIRAQ-1 uses the eddy diffusion velocity scheme
of Sklarew et al. for horizontal diffusion.
HORIZONTAL DIFFUSION? Yes, explicitly.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? Yes, but minimized.
SPATIAL RESOLUTION AND EXTENT OF MESH?
45x50 grid - 1, 2, or 5 km resolution.
RESOLUTION AND EXTENT OF TIME INCREMENT? On the order
of one to five minutes.
BOUNDARY CONDITIONS?
CO, NO, HC1, and HC2 fluxes are specified at each
of the four horizontal boundaries and above
the inversion. These are assumed to be
uniform in time.
INITIAL CONDITIONS? Station data, where available, is
used to initialize the concentration field.
NUMBER OF VERTICAL LAYERS? 1.
BACKGROUND DATA? Yes.
SPECIES:
MULTIPLE SPECIES?
WHICH REACTIVE SPECIES? None.
WHICH NON-REACTIVE SPECIES? CO,NO,HC1,HC2.
DEPOSITION?
WET? No.
DRY? Yes.
DECAY? Yes.
CHEMISTRY? No.
COMPUTED DATA:
AVERAGES? No, only short-term concentrations.
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Run time dependent.
3 HOUR? Run time dependent.
24 HOUR? Run time dependent.
VALIDATION HISTORY? Limited validation history.
(See MacCracken and Sauter, 1975.)
APPLICABLE TO FOUR CORNERS REGION? No, only the
San Francisco Bay area. However, in principle could
29
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be modified in principle for the Four Corners region
INCORPORATION OF OBSERVED DATA?
Initial conditions include station data to
initialize the concentration field, but not
real time data.
CALIBRATION POTENTIAL? Dependent on existence of observed
data for each species in the Four Corners Region.
USAGE CRITERIA:
USER'S MANUAL? Yes.
AVAILABILITY OF THE MODEL? In public domain, but only implemented
on the LBL and LLL systems.
EASE OF MODIFYING MODEL? Not assessable at this time.
EASE OF USING MODEL? Problem formulation language makes model
usage quite simple; results require skilled interpretation
VOLUME OF DATA REQUIRING MANUAL PREPARATION?
Meteorology - Substantial labor may be
needed to generate the wind field from MASCON.
The data required are the average inversion
height, surface wind speed, and wind direction,
and/or the mean layer wind speed and wind
direction for every three hours. MASCON is
limited to a grid size of 65x65 with a resolution
of 1, 2, or 5 km.
Topography - Topographic heights averaged over
1 km cells of a Universal Transverse grid
for the entire computational region.
Source emission inventory - In general a substan-
tial amount of work is required. The following
sources are considered:
mobile
population-distributed
airport
major ground sources - ground-based and
elevated
ERROR DIAGNOSTICS? Some, in problem formulation.
EASE OF MODEL INSTALLATION ON UNIVAC? Impossible at present-
program architecture requires a CDC 7600.
EASE OF MODEL MAINTENANCE? Good.
OUTPUT INTERPRETATION REQUIREMENTS? Substantial.
30
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OPERATION:
CORE REQUIREMENTS? Substantial, requires all the core available
to a CDC 7600.
ON LINE STORAGE REQUIREMENTS? High.
COMPUTATIONAL TIME REQUIREMENTS? One hour for 24 hour simulation.
INPUT DATA PREPARATION TIME REQUIREMENTS? Substantial (see above)
REFERENCES FOR LIRAQ-1 MODEL:
Boris, J. P., and D. L. Book, 1973: Flux Corrected
Transport - I, SHASTA, a Fluid Transport
Algorithm that Works. J. Comp. Phys., Vol. 11,
38 - 69.
Bass, A., A. Q. Eschenroeder, and B. A. Egan, 1977: The
Livermore Regional Air Quality Model (LIRAQ):
A Technical Review and Market Analysis.
Docement P-23H8-1, Environmental Research &
Technology, Inc., Concord, Mass.
MacCracken, M. C. (ed.), 1975: User's Guide to the
LIRAQ Model: An Air Pollution Model for the
San Francisco Bay Area, Report UCRL-S1983,
Lawerance Livermore Laboratory, Livermore, CA.
MacCracken, M. C., and G. D. Sauter (editors), 1975:
Development of an Air Pollution Model for the
San Francisco Bay Area. Volume 1, Report UCRL-
S1920, Vol. 1; Volume 2. Appendices, Report
UCRL-S1920, Vol. 2, Lawrence Livermore Laboratory,
Livermore, CA.
Dickerson, M. H., 1976: "MASCON- A Mass Consistent
Atmospheric Flux Model for Regions with
Complex Terrain", Preprint UCRL-79157, Rev. 2,
Lawrence Livermore Laboratory, Livermore, CA.
Sherman, C. A., 1975: "A Mass-Consistent Model for Wind
Fields over Complex Terrain",Preprint UCRL-76171,
Rev. 1, Lowrence Livermore Laboratory, Livermore,
CA.
31
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7. LIRAQ-2 MODEL
LIRAQ is a very large regional-scale air quality
simulation model developed by Lawrence Livermore Laboratories and
the BAAPCD to predict the spatial and temporal variations in the
concentrations of the most significant photochemically reactive
and non-reactive air pollutants throughout the San Francisco Bay
Area. LIRAQ-2 is the reactive version. It takes into explicit
account the complex topography meteorology, and source inventory
of the Bay Area. LIRAQ-2 is implementable at present only on a
CDC-7600 and specifically at the Lawrence Livermore Laboratory
and the Lawrence Berkeley Laboratory.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
LIRAQ uses the mass consistent wind fields
generated by the program MASCON (Dickerson,1976;
Sherman,1975)
VERTICAL RESOLUTION? No, vertical wind
profile assumed, model uses vertically
integrated layer.
GRIDDED INPUT? Yes
SPATIAL EXTRAPOLATION TECHNIQUE?
Missing data is interpolated or
extrapolated manually on the basis
of expert meteorological judgement
or prior experience.
INPUT TIME INTERVAL? Every three hours.
DIVERGENCE FREE? Yes,
SMOOTHING? ???
ADJUSTED FOR MIXING LID? Yes, explicitly.
MIXING LID:
INPUT SPATIAL REQUIREMENT?
For as many grid points as are
available or are needed to define
the meteorological structure.
SPATIAL EXTRAPOLATION? Same as wind field.
INPUT TEMPORAL REQUIREMENT? Every three hours.
TURBULENCE DATA:
32
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DIFFUSIVITY OR STABILITY? Diffusivity.
INPUT SPATIAL REQUIREMENT? None, K is
calculated internally.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? None.
OTHER METEOROLOGICAL DATA?
Radiative and other data as required by
the photochemical system.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? Yes.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? No.
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN?
IMPLICIT OR EXPLICIT? Explicit in wind field
WIND FIELD ADJUSTED FOR TERRAIN? Yes.
MIXING LID ADJUSTED FOR TERRAIN? Yes.
VARIABLE RECEPTOR HEIGHTS? Yes.
VARIABLE SOURCE HEIGHTS? Yes?
TRANSPORT:
ADVECTIVE METHOD?
DIFFUSIVE METHOD?
Because of the nature of the stiff differential
equations involved in the photochemical system, the time
stepping is done using a modified Gear method. This
method makes it impossible to use current pseudo-diffusion
suppressing techniques for the spatial integrations. The
spatial integrations are done by a backward or upstream
1st order diffence scheme which may become dominated
by pseudo-diffusive errors.
HORIZONTAL DIFFUSION? Yes, explicitly.
33
-------
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? Substantial.
SPATIAL RESOLUTION AND EXTENT OF MESH?
20x20 grid - 1, 2, or 5 km resolution.
RESOLUTION AND EXTENT OF TIME INCREMENT?
60 to several hundred seconds.
BOUNDARY CONDITIONS?
Specification of species fluxes or concentrations
at the lateral and vertical boundries. These are assumed
to be uniform in time.
INITIAL CONDITIONS? Station data is used to initialize
the concentration field.
NUMBER OF VERTICAL LAYERS? 1.
BACKGROUND DATA? Yes.
SPECIES:
MULTIPLE SPECIES?
WHICH REACTIVE SPECIES?
Up to 15 chemically reactive species plus four
species which are assumed to be in instantaneous
equilibrium. The 15 chemically reactive species
are: alkene-like hydrocarbons, alkane-like
hydrocarbons, aldehyde-like hydrocarbons,
nitrous acid, nitric acid, hydrogen peroxide,
nitric oxide, nitrogen dioxide, nitrogen pentoxide,
ozone, alkyl nitrites, alkyperoxyl radicals,
hydroperoxyl free radicals and carbon monoxide.
DEPOSITION?
WET? No.
DRY? Yes.
DECAY? Yes.
CHEMISTRY? Yes.
LINEAR? No.
NON-LINEAR? Yes.
WHAT CHEMICAL SYSTEM? After Hecht et al. [1974]
with different reaction times.
COMPUTED DATA:
AVERAGES? No, only short-term concentrations.
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Run-time dependent.
3 HOUR? Run-time dependent.
24 HOUR? Run-time dependent.
VALIDATION HISTORY? Very limited validation history.
MacCracken, M. C., and G. D. SauterCeditors),
34
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1975: Development of an Air Pollution for
the San Francisco Bay Area. Volume 1,
Report UCRL-S1920, Vol. 1; Volume 2.
Appendices, Report UCRL-S1920, Vol. 2,
Lawrence Livermore Laboratory, Livermore, CA,
APPLICABLE TO FOUR CORNERS REGION? No, only the
San Francisco Bay area. However, in principle
could be modified for the Four Corners region.
INCORPORATION OF OBSERVED DATA?
Initial conditions include station data to
initialize the concentration field, but not
real time data.
CALIBRATION POTENTIAL? Dependent on existence of observed
data for each species in the Four Corners Region.
USAGE CRITERIA:
USER'S MANUAL? Yes.
AVAILABILITY OF THE MODEL? In public domain, but presently only
on the Berkeley LBL system.
EASE OF MODIFYING MODEL? Not assessable at this time.
EASE OF USING MODEL?
Problem formulation language makes model usage quite
simple; results require skilled interpretation.
VOLUME OF DATA REQUIRING MANUAL PREPARATION?
Meteorology - Substantial labor may be
needed to generate the wind field from MASCON.
The data required are the average inversion
height, surface wind speed, and wind direction,
and/or the mean layer wind speed and wind
direction for evevy three hours. MASCON is
limited to a grid size of 65x65 with a resolution
of 1, 2, or 5 km.
Topography - Topographic heights averaged over
1 km cells of a Universal Transverse grid for
for the entire computational region.
Source emission inventory - A substantial amount
of work is required. The following sources are
considered:
mobile
population-distributed
airport
major ground sources - ground-based and
elevated
ERROR DIAGNOSTICS? Some in the problem formulation.
35
-------
EASE OF MODEL INSTALLATION ON UNIVAC? Impossible at present
program architecture requires a CDC-7600.
EASE OF MODEL MAINTENANCE? Good.
OUTPUT INTERPRETATION REQUIREMENTS? Substantial.
OPERATION:
CORE REQUIREMENTS? Substantial, requires all the core available
to a CDC 7600.
ON LINE STORAGE REQUIREMENTS? Very high.
COMPUTATIONAL TIME REQUIREMENTS? One hour
INPUT DATA PREPARATION TIME REQUIREMENTS?
for 24 hour
Substantial
simulation.
(see above)
REFERENCES:
Boris
. P., and D
Transport - I,
Algorithm that
33 - 69.
L. Book,
SHASTA, a
Works. J.
1973: Flux Corrected
Fluid Transport
Comp. Phys., Vol. 11
Bass, A., A. Q. Eschenroeder, and B. A. Egan, 1977:
Livertnore Regional Air Quality Model (LIRAQ):
A Technical Review and Market Analysis.
Document P-2348-1, Environmental Research &
Technology, Inc., Concord, Mass.
MacCracken, M. C. (ed.), 1975: User's Guide to the
LIRAQ Model: An Air Pollution Model for the
San Francisco Bay Area, Report UCRL-S1983,
Lawerance Livermore Laboratory, Livermore, CA
The
MacCracken, M. C.,
San Francisco
S1920, Vol. 1
and G. D. Sauter (editors), 1975:
Bay Area. Volume 1, Report UCRL-
; Volume 2. Appendices, Report
UCRL-S1920, Vol. 2, Lawrence Livermore Laboratory
Livermore, CA.
Hecht, T. A., J. H. Seinfeld, and M. C. Dodge, 1974:
Further Development of a Generalized Kinetic
Mechanism for Photochemical Smog. J. Environ.
Sci. Technol. Vol. 8, 327.
Dickerson,M.H., 1976:"MASCON - A Mass Consistent
Atmospheric Flux Model for Regions with
Complex Terrain".Preprint UCRL-761577, Rev. 2,
Lawrence Livermore Lab.,Livermore,Ca.
Sherman, C.A.,1975: "A Mass Consistent Model for Wind
Fields over Complex Terrain",Preprint UCRL-76171
Rev .
1 , Lawrence
Livermore Lab ., Livermore,CA
36
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8. SHIR-SHIEH MODEL
This a generalized urban air pollution model based on
numerical integration of the conservation of species equation.
The model computes the temporal and three-dimensional spatial
distributions resulting from specified multiple point and area
sources . Special treatments of the finite difference scheme to
aceomodate the large variations of concentrations are
incorporated.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION?
Vertical wind speeds are interpolated by
a power law. Wind direction is assumed vertically
uniform.
SINGLE STATION? Yes.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
The initial wind field is derived by
assigning the wind vector from the closest station
This initial wind field is "smoothed" by a 1/r**2
inverse weighting.
INPUT TIME INTERVAL? Hourly
TEMPORAL INTERPOLATION TECHNIQUE? None.
DIVERGENCE FREE? No.
SMOOTHING? Yes.
ADJUSTED FOR MIXING LID? No.
MIXING LID:
INPUT SPATIAL REQUIREMENT? Uniform in space.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
TURBULENCE DATA:
37
-------
DIFFUSIVITY OR STABILITY?
Vertical diffusivity calculated from
a continuous stability class based on Turner's
method. Horizontal diffusivity is constant.
INPUT SPATIAL REQUIREMENT? Each grid point.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? Sky cover.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? Yes.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? Yes.
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN? No.
TRANSPORT:
ADVECTIVE METHOD?
DIFFUSIVE METHOD?
A second-order, centered finite-difference scheme
is used to integrate the advection and horizontal terms
and the Crank-Nicholson method is used for the vertical
diffusion term.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? Yes.
SPATIAL RESOLUTION AND EXTENT OF MESH? 30 by 40 by 14
3 dimensional grid with 5000 ft spacing.
RESOLUTION AND EXTENT OF TIME INCREMENT?
The time increment is on the order of 2000 seconds
38
-------
Extent of integration is 24 hours.
BOUNDARY CONDITIONS?
Boundary surfaces above and below assumed
impermeable to S02. Continuity of flow across
vertical sufaces.
INITIAL CONDITIONS?
Initial concentrations set equal to 0.
NUMBER OF VERTICAL LAYERS? 14.
BACKGROUND DATA? No.
SPECIES:
MULTIPLE SPECIES? No.
WHICH REACTIVE SPECIES? Only S02.
WHICH NON-REACTIVE SPECIES? None.
DEPOSITION? No.
DECAY? Yes.
CHEMISTRY? Yes.
LINEAR? Yes.
NON-LINEAR? No.
WHAT CHEMICAL SYSTEM? Linear decay of S02.
COMPUTED DATA:
AVERAGES? Yes.
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Yes.
3 HOUR? Yes.
24 HOUR? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? No.
VALIDATION HISTORY?
CC Shir and L.J. Shieh, "A Generalized Urban Air
Pollution Model and Its Application to the Study of S02
Distributions in the St. Louis Metropolitan Area.",J.A.M. Vol 13,
pp 185-204 (1974)
APPLICABLE TO FOUR CORNERS REGION?
Given its limitations, it would be applicable in
principle for short averaging times if modified.
CALIBRATION POTENTIAL? Not known at this time.
USAGE CRITERIA:
USER'S MANUAL? Not presently known
39
-------
AVAILABILITY OF THE MODEL? Developmental and probably not user
oriented.
EASE OF MODIFYING MODEL? Not presently known.
EASE OF USING MODEL? Not presently known.
VOLUME OF DATA REQUIRING MANUAL PREPARATION?
Source emission inventory must be large. Hourly
meteorological input requirements are small.
ERROR DIAGNOSTICS? Not presently known.
EASE OF MODEL INSTALLATION ON UNIVAC? Not presently known.
EASE OF MODEL MAINTENANCE? Not presently known.
OUTPUT INTERPRETATION REQUIREMENTS? A large volume of output
requires substantial labor to reduce and interpret.
OPERATION:
CORE REQUIREMENTS? Not presently known.
ON LINE STORAGE REQUIREMENTS? Not presently known.
COMPUTATIONAL TIME REQUIREMENTS?
A 24 hour simulation requires 3 to 5 minutes on IBM 360
INPUT DATA PREPARATION TIME REQUIREMENTS? Substantial.
OTHER HARD WARE REQUIREMENTS? Not presently known.
REFERENCES FOR SHIR-SHIEH MODEL:
C.C. Shir and L . J . Shieh , 1 974: "A Generalized Urban Air Pollution
Model and
Its Application to the Study of S02 Distributions in the St.
Louis Metropolitan Area", J.A.M. Vol 13, PP 185-204
Shir, C. C. ,1973:"A preliminary numerical study of atmospheric
turbulent flows in the idealized planetary boundary
layer",J.Atmos.Sci , Vol 30, pp 1327-1339
Shir, C. C., 19?2:"A numerical computation of air flow over a
sudden change in surface roughness" , J. Atmos. Sci. Vol 29, pp
304-310
Shir, C. C., 1972:"Numerical investigation of the atmospheric
dispersion of stack effluents.",IBM J. Res. Devel. Vol 16, pp
172-179
Shieh,L.J., P.K.Halpern, B. A. Clemens, H.H. Wang, and
F.F.Abraham,1972: "Air Quality Diffusion Model: Application to
New York City",IBM J.Res. Devel., Vol 16, pp 162-170
Shir, C. C.,1970:"A pilot study in numerical techniques for
predicting air pollutant distribution downwind from a stack", J.
Atmos. Env. Vol 4 pp 387-407
40
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9. MESODIF MODEL
MESODIF (for mesoscale diffusion) uses an objective
regional trajectory analysis scheme combined with a Gaussian
diffusion model to simulate regional scale dispersion effects.
The trajectory analysis scheme uses wind data from a
network of tower mounted wind sensors to consider the effects of
spatial variability of horizontal wind flow near the surface,
incorporates time changes in rates of diffusion, and an upper
level lid to bound vertical mixing.
Continuous emissions sources are modeled as a sequence of
instantaneous puffs which diffuse in the vertical and horizontal
by a Gaussian formula for an instantaneous release. At each time
step the puffs are advected by the time field and sampled at each
of the receptors. The Gaussian dispersion coefficients are
functions of the distance from the source.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? None.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
1/r**2 extrapolation to grid points,
linear interpolation from grid points to
puff points.
INPUT TIME INTERVAL? Hourly.
TEMPORAL INTERPOLATION TECHNIQUE? Linear.
DIVERGENCE FREE? No.
SMOOTHING? No.
ADJUSTED FOR MIXING LID? No, but could be modified
MIXING LID:
INPUT SPATIAL REQUIREMENT? Uniform in space.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
TEMPORAL INTERPOLATION? Persistence.
TURBULENCE DATA: Stability Class
INPUT SPATIAL REQUIREMENT? Uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly.
TEMPORAL INTERPOLATION? Persistence.
-------
OTHER METEOROLOGICAL DATA? None.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? No.
AREA SOURCES? No.
MULTIPLE SOURCE SITES? No. .
TIME DEPENDENT SOURCE STRENGTHS? No.
INSTANTANEOUS SOURCE EMISSIONS? Yes.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN? No.
TRANSPORT:
ADVECTIVE METHOD?
Simple Euler integration.
DIFFUSIVE METHOD?
MESODIF models the emission releases as a series
of puffs. At each time step, the puff centers are advected
by the local wind field. Then the concentrations are
diffused by the Gaussian law, with vertical and horizontal
standard deviations calculated from the total distance
traveled and the current stability, as well as from the
accumulated sigmas acquired thus far.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? None.
SPATIAL RESOLUTION AND EXTENT OF MESH?
MESODIF has a 26 by 32 grid, with user specified
x and y grid spacing.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Puffs may be released at various user specified
interval, and advected at user specified interval.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
BACKGROUND DATA? No.
-------
SPECIES:
MULTIPLE SPECIES? No.
WHICH REACTIVE SPECIES? None.
WHICH NON-REACTIVE SPECIES? Any passive species
(eg. S02, TSP, etc).
DEPOSITION? No.
DECAY? No.
CHEMISTRY? No.
COMPUTED DATA:
AVERAGES? Yes. (Non-overlapping)
LONG TERM(ANNUAL)? Yes.
SHORT TERM? Yes.
1 HOUR? Yes.
3 HOUR? Yes.
2M HOUR? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? Can be modified to print instantaneous
plume as superposition of puff streak
trajectories, an important advantage in variable
flow situations.
VALIDATION HISTORY?
"Regional Effluent Dispersion Calculations
Considering Spatial and Temporal Meteorological
Variations", G.E. Start and L.L. Wendell
NOAA Technical Memorandum ERL ARL-4M (1974)
APPLICABLE TO FOUR CORNERS REGION?
The model is, with the necessary modifications,
applicable to the Four Corners region.
INCORPORATION OF OBSERVED DATA? No.
CALIBRATION POTENTIAL? Good, given adequate observed data
USAGE CRITERIA:
USER'S MANUAL? Yes, but not user oriented.
AVAILABILITY OF THE MODEL? In the public domain.
EASE OF MODIFYING MODEL? Relatively short code facilitates
incorporation of improvements.
EASE OF USING MODEL? Relatively easy, given meteorological data
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Small.
ERROR DIAGNOSTICS? Minimal.
EASE OF MODEL INSTALLATION ON UNIVAC? Relatively easy.
EASE OF MODEL MAINTENANCE? Relatively easy.
OUTPUT INTERPRETATION REQUIREMENTS? Average.
OPERATION:
-------
CORE REQUIREMENTS? 150k bytes.
ON LINE STORAGE REQUIREMENTS? None.
COMPUTATIONAL TIME REQUIREMENTS? 30 rains./data year (IBM 370)
dependent on puff resolution used.
INPUT DATA PREPARATION TIME REQUIREMENTS? 1 hour
OTHER HARD WARE REQUIREMENTS? 2 tape drives/met station
REFERENCES FOR MESODIF MODEL:
G. E. Start and L. i
Dispersion Calculations
Meteorological Variations",
Wendell,1974: "Regional Effluent
Considering Spatial and Temporal
NOAA Technical Memorandum ERL ARL-44
Wendell, L. L.,1972:"Mesoscale Wind
Estimates Determined From
Rev. Vol 100 No.7 pp 565-578
a Network of
Field and Transport
Wind Towers",Mon. Wea.
Wendell, L. L.,1970:"A preliminary examination of
mesoscale wind fields and transport determined from a network of
towers", NOAA Tech. Memo. ERLTM-ARL 25, U.S.Dept. of Commerce,Air
Resources Lab.,Silver Spring, Md.,25 p + appendices.
G. E., and E. H. Markee, Jr.,1967:"Relative dose
Start,
factors from
long-period point
Proc. of the USAEC
River Nuclear Labs.,Chalk River, Ontario, Sept 11-14, 1967, C.A
Manson (ed.) AECL-2787, pp 59-67
source emissions of atmospheric pollutants",
Meteorological Information Meeting, Chalk
Dickson, C. R
Richter
Test Reactor"
G. E. Start, E. H.
and J. Kearns, 1967:"Meteorology
2d. Progress Report, Jan
Markee
for the
1966
IDO-12059, ESSA
Falls, Idaho
Air Resources Field Research
Jr, A. P.
Loss-of-Fluid
- Jan. 1967,
Office, Idaho
10. ELIASSEN-SALTBONES ONE-LAYER MODEL
This model is a simple Lagrangian dispersion model which
incorporates deposition and a linear transformation of sulfur
dioxide to sulfates. The pollutants are modeled as marked
particles with the concentrations attached to each particle
modified at each time step as indicated by the removal,
-------
deposition, and transformation equations. The particles are
advected by a method described by Petterssen [1956].
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? None.
SINGLE STATION? No.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? No.
SPATIAL EXTRAPOLATION TECHNIQUE? Analyzed.
INPUT TIME INTERVAL? 6 hour.
TEMPORAL INTERPOLATION TECHNIQUE? Linear.
SMOOTHING? Analyzed.
ADJUSTED FOR MIXING LID? No.
MIXING LID:
INPUT SPATIAL REQUIREMENT? Uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
TURBULENCE DATA: None.
OTHER METEOROLOGICAL DATA? None.
EMISSIONS:
SOURCE INVENTORY: Gridded source inventory.
ELEVATED SOURCES? No.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? Yes.
INSTANTANEOUS SOURCE EMISSIONS? Yes.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No.
TERRAIN? Not considered.
TRANSPORT:
-------
ADVECTIVE METHOD?
Every hour particles are advected by an iterative
2-point Runge-Kutta technique described by Petterssen [1956]
Every 12 hours, the particles are condensed to one particle
per grid cell.
DIFFUSIVE METHOD? None.
HORIZONTAL DIFFUSION? None.
VERTICAL DIFFUSION? None.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH? 32 by 32 grid
with a spacing of 270 km.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Time step of 1 hour, 6 month duration.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
BACKGROUND DATA? None.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? S02, SOM
WHICH NON-REACTIVE SPECIES? None.
DEPOSITION? Yes.
WET? No.
DRY? Yes, using the deposition velocity
concept .
DECAY? Removal rate for sulfates.
CHEMISTRY? Yes.
LINEAR? Yes.
NON-LINEAR? No.
WHAT CHEMICAL SYSTEM? S02 to S04
COMPUTED DATA:
AVERAGES? Yes.
LONG TERM(ANNUAL)? Yes.
SHORT TERM? Yes.
1 HOUR? No.
3 HOUR? No.
24 HOUR? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? No.
VALIDATION HISTORY?
"Sulfur Transport and Dry Depostion Over Europe Described
46
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by a Simple Lagrangian Dispersion Model", A. Eliassen and J
Saltbones, Norwegian Institute for Air Research (1976)
APPLICABLE TO FOUR CORNERS REGION?
Given its limitations, it is applicable to the
Four Corners Region if modified to include terrain.
INCORPORATION OF OBSERVED DATA? Yes.
CALIBRATION POTENTIAL? Unknown at this time.
USAGE CRITERIA:
USER'S MANUAL? Unknown at this time.
AVAILABILITY OF THE MODEL? Developmental
EASE OF MODIFYING MODEL? Unknown at this time.
EASE OF USING MODEL? Unknown at this time.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Unknown at this time
ERROR DIAGNOSTICS? Unknown at this time.
EASE OF MODEL INSTALLATION ON UNIVAC? Unknown at this time.
EASE OF MODEL MAINTENANCE? Unknown at this time.
OUTPUT INTERPRETATION REQUIREMENTS? Unknown at this time.
OPERATION:
CORE REQUIREMENTS? Unknown at this time.
ON LINE STORAGE REQUIREMENTS? Unknown at this time.
COMPUTATIONAL TIME REQUIREMENTS? Unknown at this time.
INPUT DATA PREPARATION TIME REQUIREMENTS? Unknown at this time.
REFERENCES FOR ELIASSEN-SALTBONES ONE-LAYER MODEL:
Eliassen, A. and J. Saltbones, 1976: "Sulphur Transport and Dry
Deposition Over Europe Described by „ a Simple Lagrangian
Dispersion Model.", Norwegian Institute for Air Research
Petterssen, S.,1956: Weather Analysis and Forecasting, McGraw
Hill p 27
Elisen A. and J. Saltbones, 1975: "Decay and Transformation Rates
of S02 as Estimated from Emission Data , Trajectories,and Measured
Air Concentrations" Atmos.Env. Vol 9 pp 425-429
Bolin B. and Persson C.,1975: "Regional Dispersion and Deposition
of Atmospheric Pollutants with Particular Application to Sulfur
Pollution over Western Europe." Tellus Vol 27 pp 281-310
-------
11. ELIASSEN-SALTBONES TWO-LAYER MODEL
This model is an extension of the one-layer model to two
layers (to account for low and high sources) with different wind
fields for horizontal advection in each layer, and with a simple
turbulent exchange mechanism between the layers.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Two layers.
SINGLE STATION? No.
GRIDDED INPUT? Yes.
ARBITRARY STATION INPUT? No.
SPATIAL EXTRAPOLATION TECHNIQUE? Analyzed.
INPUT TIME INTERVAL? 6 hour.
TEMPORAL INTERPOLATION TECHNIQUE? Linear.
SMOOTHING? Analyzed.
ADJUSTED FOR MIXING LID? No.
MIXING LID:
INPUT SPATIAL REQUIREMENT? Uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
TURBULENCE DATA: Turbulent exchange velocity field.
OTHER METEOROLOGICAL DATA? None.
EMISSIONS:
SOURCE INVENTORY: Gridded source inventory.
ELEVATED SOURCES? Yes.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? Yes.
INSTANTANEOUS SOURCE EMISSIONS? Yes.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
48
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ARBITRARY LOCATIONS? No.
TERRAIN? Not considered.
TRANSPORT:
ADVECTIVE METHOD?
Every hour particles are advected by an iterative
2-point Runge-Kutta technique described by Petterssen [1956].
Every 12 hours, the particles are condensed to one particle
per grid cell .
DIFFUSIVE METHOD?
The vertical flux of q from the top to the
bottom layer is approximated by
F = 2 K (q1-qO)/(h1+hO)
where q1,qO,h1,hO are the S02 concentrations and
depths of the top and bottom layers, and K is the
vertical eddy-diffusivity between the layers.
HORIZONTAL DIFFUSION? None.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH? 32 by 32 by 2
grid with a spacing of 270 km. in the
horizontal, 200m and 800m in the vertical
RESOLUTION AND EXTENT OF TIME INCREMENT?
Time step of 1 hour, 6 month duration.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? Two.
BACKGROUND DATA? None.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? S02, S04
WHICH NON-REACTIVE SPECIES? None.
DEPOSITION? Yes.
WET? No.
DRY? Yes, using the deposition velocity
concept.
DECAY? Removal rate for sulfates.
CHEMISTRY? Yes.
LINEAR? Yes.
NON-LINEAR? No.
WHAT CHEMICAL SYSTEM? S02 to S04
-------
COMPUTED DATA:
AVERAGES? Yes.
LONG TERM(ANNUAL)? Yes.
SHORT TERM? Yes.
1 HOUR? No.
3 HOUR? No.
24 HOUR? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? No.
VALIDATION HISTORY? Limited.
APPLICABLE TO FOUR CORNERS REGION?
Given its limitations, it is applicable to
the Four Corners Region if modified for terrain.
INCORPORATION OF OBSERVED DATA? Yes.
CALIBRATION POTENTIAL? Unknown at this time.
USAGE CRITERIA:
USER'S MANUAL? Unknown at this time.
AVAILABILITY OF THE MODEL? Developmental.
EASE OF MODIFYING MODEL? Unknown at this time.
EASE OF USING MODEL? Unknown at this time.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Unknown at this time
ERROR DIAGNOSTICS? Unknown at this time.
EASE OF MODEL INSTALLATION ON UNIVAC? Unknown at this time.
EASE OF MODEL MAINTENANCE? Unknown at this time.
OUTPUT INTERPRETATION REQUIREMENTS? Unknown at this time.
OPERATION:
CORE REQUIREMENTS? Unknown at this time.
ON LINE STORAGE REQUIREMENTS? Unknown at this time.
COMPUTATIONAL TIME REQUIREMENTS? Unknown at this time.
INPUT DATA PREPARATION TIME REQUIREMENTS? Unknown at this time.
REFERENCES FOR ELIASSEN-SALTBONES TWO-LAYER MODEL:
Eliassen, A. and J. Saltbones,1976: "Sulphur Transport and Dry
Deposition Over Europe Described by a Simple Lagrangian
Dispersion Model.", Norwegian Institute for Air Research
Petterssen, S.,1956: Weather Analysis and Forecasting, McGraw
Hill , p27
Elaissen, A. and Saltbones, J.,1975: "Decay and transformation
rates of S02 as Estimated From Emission Data,Trajectories and
50
-------
Measured Air Concen- trations.",Atmos.Env. Vol 9 pp M25-M29
Bolin B. and Persson C.,1975: "Regional Dispersion and Deposition
of Atmospheric Polutants with Particular Application To Sulfur
Pollution over Western Europe",Tellus Vol 27 pp 281-310
Eliassen, A. and Saltbones, J. 1975: "A Two Layer Dispersion
Model: Description and a Few Results", Norwegian Institute for
Air Research,
12. WENDELL-POWELL-DRAKE MODEL
This model is a trajectory model intended primarily for
calculating the transport, diffusion, and deposition of effluents
on regional and continental scales. A month, season, or year of
trajectories at 6-hourly time intervals may be calculated forward
or backward in time from any origin in the Northern Hemisphere
for duratiTns up to 10 days.
Tb plume is modeled as a series of plume segments which
are diff : 1 • the Gaussian formula in the vertical and in the
directi n nc.rmal to the wind flow. The downwind length of each
segment i '„• d c. where U is the mean wind speed and dt is the time
increrr.ent ,
The model incorporates wet and dry deposition as well as
linear transformation of S02 to S04.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Vertically averaged winds.
SINGLE STATION? Yes.
GRIDDED INPUT? Yes (analyzed).
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
This model computes grid point winds
from station winds by weighting the observations
of all stations within a radius R by distance and
alignment. While the user may select various
parameter values, the model is set up for a radius
R=300 nautical miles and for a distance weighting
factor of 1/r**2 and an alignment weighting factor
of 1-.5 abs(sin(a)) if r is the distance to the
station and a its angle relative to the wind at a.
The model uses a bilinear interpolation
from corner grid points to the interior of a cell.
51
-------
INPUT TIME INTERVAL? 12 hours or 6 hours.
TEMPORAL INTERPOLATION TECHNIQUE?
The model assumes persistence of the
winds reported closest to the calculation time.
(No trajectory is calculated if the wind data
is missing for the 2 or 3 closest time periods.)
DIVERGENCE FREE? No.
SMOOTHING? If analyzed.
ADJUSTED FOR MIXING LID?
Vertically averaged
MIXING LID
INPUT SPATIAL REQUIREMENT? Uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant
TEMPORAL INTERPOLATION? None.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Stability.
INPUT SPATIAL REQUIREMENT? Constant.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? Yes.
AMBIENT TEMPERATURE? No.
AMBIENT PRESSURE? No.
PRECIPITATION RATE? Yes.
SOLAR RADIATION? No.
SURFACE HEAT FLUXES? No.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? Yes.
AREA SOURCES? No.
MULTIPLE SOURCE SITES? No.
TIME DEPENDENT SOURCE STRENGTHS? No
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
52
-------
ARBITRARY LOCATIONS? No.
TERRAIN? No.
TRANSPORT:
This model computes trajectories for up to 10 days
using U dt increments where dt=1 hours and U is the
computed wind at the current point in space and time.
Trajectories are started every six hours.
DIFFUSIVE METHOD?
The plume is modeled as a series of plume segments
which diffuse vertically and crosswind according to the
ground level Gaussian formula for a continuous point
source. The vertical and crosswind standard deviations are
approximated by a function of downwind distance and
stability class. Each segment has a downwind length equal
to U dt where U is the mean wind speed and dt is the
time increment.
HORIZONTAL DIFFUSION? Yes (on option).
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH?
The model is organized to compute on a large
scale grid which is about 31* km square.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Intended for monthly, seasonal applications
with a time increment of 3 hours.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
BACKGROUND DATA? None.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? S02.SOM.
WHICH NON-REACTIVE SPECIES? S02,TSP,etc.
DEPOSITION? Yes.
WET?
Precipitation scavenging is based
on an empirically derived average scavenging
ratio (Engelmann , 1970 ) .
DRY?
The concept of deposition velocity is
used to calculate dry deposition amounts along
53
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a trajectory.
DECAY? No.
CHEMISTRY? No.
COMPUTED DATA:
AVERAGES? Yes.
LONG TERM(ANNUAL)? Yes.
SHORT TERM? No.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? Yes.
VALIDATION HISTORY? Limited.
APPLICABLE TO FOUR CORNERS REGION?
Yes, with suitable modifications.
CALIBRATION POTENTIAL? Good, given adequate observed data
USAGE CRITERIA:
USER'S MANUAL? No.
AVAILABILITY OF THE MODEL? In the public domain.
EASE OF MODIFYING MODEL? Some difficulty due to lack of
documentation.
EASE OF USING MODEL? Some difficulty due to lack of documentation.,
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Moderate.
ERROR DIAGNOSTICS? Unable to assess.
EASE OF MODEL INSTALLATION ON UNIVAC? Moderate.
EASE OF MODEL MAINTENANCE? Moderate.
OUTPUT INTERPRETATION REQUIREMENTS? Minor.
OPERATION:
CORE REQUIREMENTS? Moderate.
ON LINE STORAGE REQUIREMENTS? Moderate.
COMPUTATIONAL TIME REQUIREMENTS?
15 minutes/data month for 30 sources on CDC 6600
INPUT DATA PREPARATION TIME REQUIREMENTS? ???
REFERENCES FOR WENDELL-POWELL-DRAKE MODEL:
Wendell, L., L. Powell, D. C., Drake R. L.,1976:"A Regional Scale
Model For Computing Deposition and Ground Level Air of S02 and
Sulfates From Elevated and Ground Sources", Proc. Third Symposium
on Atmos. Turbulence, Diffusion and Air Quality, AMS, Raleigh, NC
,pp 318-324
-------
13. HEFFTER-TAYLOR-FERBER LONG-TERM MODEL
This model is a trajectory model intended primarily for
calculating the transport, diffusion, and deposition of effluents
on regional and continental scales. A month, season, or year of
trajectories at 6-hourly time intervals may be calculated forward
or backward in time from any origin in the Northern Hemisphere
for arbitrary durations. A Gaussian plume model is combined with
the trajectory model to calculate long-term mean average surface
air con- centrations and deposition amounts. Both wet and dry
deposition are incorporated into the model.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Vertically averaged winds.
SINGLE STATION? Multiple Station.
GRIDDED INPUT? Yes (analyzed).
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
For station input, this models computes
three hour trajectory segments
from station winds by weighting the observations
of all stations within a radius R by distance and
alignment. While the user may select various
parameter values, the model is set up for a radius
R=300 nautical miles and for a distance weighting
factor of 1/r**2 and an alignment weighting factor
of 1-.5 abs(sin(a)) if r is the distance to the
station and a its angle relative to the wind at
a station.
The model uses a bilinear interpolation
from corner grid points to the traject segment in
the cell for gridded input.
INPUT TIME INTERVAL? 12 hours or 6 hours.
TEMPORAL INTERPOLATION TECHNIQUE?
All winds are linearly interpolated
to the periods OOZ,06Z,12Z, and 18Z.
DIVERGENCE FREE? No.
SMOOTHING? If analyzed.
ADJUSTED FOR MIXING LID? Vertically averaged.
MIXING LID: Temperature profile at stations.
INPUT SPATIAL REQUIREMENT? At each station.
SPATIAL EXTRAPOLATION? Yes.
55
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INPUT TEMPORAL REQUIREMENT? Same as winds
TEMPORAL INTERPOLATION? Yes.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Diffusivity.
INPUT SPATIAL REQUIREMENT? Constant.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? Yes.
AMBIENT TEMPERATURE? Yes.
AMBIENT PRESSURE? No.
PRECIPITATION RATE? Yes.
SOLAR RADIATION? No.
SURFACE HEAT FLUXES? No.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? No.
AREA SOURCES? No.
MULTIPLE SOURCE SITES? No.
TIME DEPENDENT SOURCE STRENGTHS? No.
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? Yes.
ARBITRARY LOCATIONS? Yes.
TERRAIN? No.
TRANSPORT:
ADVECTIVE METHOD?
This model computes trajectories for up to 10 days
using U dt increments where dt=3 hours and U is the
computed wind at the current point in space and time.
Trajectories are started every six hours.
DIFFUSIVE METHOD?
Ground-level air concentration calculations
along a trajectory are based on the Gaussian plume equation
for a instantaneous point source assumed to be at ground
56
-------
level. Here sigraa z is the square root of 2 Kt where
K is the vertical diffusivity and sigma y is assumed
to be .5 t.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH?
The model is organized to compute on a large
scale grid of about 80 by 80 in extent with a spacing
of .5 degrees in latitude or longitude.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Intended for monthly, seasonal applications
with a time increment of 3 hours.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
BACKGROUND DATA? None.
SPECIES:
MULTIPLE SPECIES? No.
WHICH REACTIVE SPECIES? None.
WHICH NON-REACTIVE SPECIES? S02,TSP,etc.
DEPOSITION? Yes.
WET?
Precipitation scavenging is based
on an empirically derived average scavenging
ratio (Engelmann,1970).
DRY?
The concept of deposition velocity is
used to calculate dry deposition amounts along
a trajectory.
DECAY? No.
CHEMISTRY? No.
COMPUTED DATA:
AVERAGES? Yes.
LONG TERM(ANNUAL)? Yes.
SHORT TERM? No.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? Yes.
VALIDATION HISTORY? Limited: Heffter et al.,1975.
There are current plans for extensive testing
during the coming year.
57
-------
APPLICABLE TO FOUR CORNERS REGION?
Yes if suitably modified to take terrain into
account.
INCORPORATION OF OBSERVED DATA? In principle, yes.
CALIBRATION POTENTIAL? Not ascertained.
USAGE CRITERIA:
USER'S MANUAL? Model not externally documented.
AVAILABILITY OF THE MODEL? In the public domain.
EASE OF MODIFYING MODEL? Dependent on documentation.
EASE OF USING MODEL? Relatively easy.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Moderate.
ERROR DIAGNOSTICS? Minimal.
EASE OF MODEL INSTALLATION ON UNIVAC? Already on UNIVAC.
EASE OF MODEL MAINTENANCE? Good.
OUTPUT INTERPRETATION REQUIREMENTS? Minor.
OPERATION:
CORE REQUIREMENTS? Less than 256K on IBM 360/195
ON LINE STORAGE REQUIREMENTS? Moderate.
COMPUTATIONAL TIME REQUIREMENTS? On IBM 360/195, one data month
takes 1 minute (4 trajectories per day,5 day trajectories)
INPUT DATA PREPARATION TIME REQUIREMENTS? Not ascertained.
REFERENCES FOR HEFFTER-TAYLOR-FERBER LONG-TERM MODEL
Heffter J.L., Taylor, A.D., Ferber, G.J.,1975:"A
Regional-Continental Scale Transport, Diffusion, and Deposition
Model", NOAA Technical Memorandum ERL ARL-50
Englemann R . J., 1970:"Scavenging Prediction Using Ratios of
Concentrations in Air and Precipitation",Proc. Symposium on
Precipitation Scavenging, AEC Symposium Series 22, pp 475-485
Heffter, J.L. , 1 965:"The Variation of Horizontal Diffusion
Parameters with Time for Travel Periods of one Hour or Longer",
JAM Vol 4 , pp 153-156
Machta, L., Ferber, G. J., and Heffter, J.L.,1974:"Regional and
Global Scale Dispersion of Krypton-85 for Population-Dose
Calculations",Proc. Symposium on the Physical Behavior of
Radioactive Contaminants in the Atmosphere,IAEA,Vienna,pp 411-425
58
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14. HEFFTER, TAYLOR AND FERBER: SHORT-TERM MODEL
This model is a trajectory model intended primarily for
calculating the transport, diffusion, and deposition of effluents
on regional and continental scales. A month, season, or year of
trajectories at 6-hourly time intervals may be calculated forward
or backward in time from any origin in the Northern Herimsphere
for durations up to 10 days. The continuous emission source is
modeled as a series of instantaneous "puffs" which are advected
along the trajectory and diffused according to the Gaussian
formula for an instantaneous release. The diffusion is assumed to
be horizontally isotropic.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Vertically averaged winds.
SINGLE STATION? Yes.
GRIDDED INPUT? Yes (analyzed).
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
This models computes grid point winds
from station winds by weighting the observations
of all stations within a radius R by distance and
alignment. While the user may select various
parameter values, the model is set up for a radius
R=300 nautical miles and for a distance weighting
factor of 1/r**2 and an alignment weighting factor
of 1-.5 abs(sin(a)) if r is the distance to the
station and a its angle relative to the wind at a.
The model uses a bilinear interpolation
from corner grid points to the interior of a cell.
INPUT TIME INTERVAL? 12 hours or 6 hours.
TEMPORAL INTERPOLATION TECHNIQUE?
The model assumes persistence of the
winds reported closest to the calculation time.
(No trajectory is calculated if the wind data
is missing for the 2 or 3 closest time periods.)
DIVERGENCE FREE? No.
SMOOTHING? If analyzed.
ADJUSTED FOR MIXING LID? Vertically averaged.
MIXING LID:
INPUT SPATIAL REQUIREMENT? Uniform.
SPATIAL EXTRAPOLATION? None.
59
-------
INPUT TEMPORAL REQUIREMENT? Constant
TEMPORAL INTERPOLATION? None.
TURBULENCE DATA
DIFFUSIVITY Ofl STABILITY? Diffusivity
INPUT SPATIAL REQUIREMENT? Constant.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? No.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? No.
AREA SOURCES? No.
MULTIPLE SOURCE SITES? No.
TIME DEPENDENT SOURCE STRENGTHS? No.
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? Yes.
ARBITRARY LOCATIONS? Yes.
TERRAIN? No.
TRANSPORT:
ADVECTIVE METHOD?
This model computes trajectories for up to 10 days
using U dt increments where"dt = 3 hours and U is the
computed wind at the current point in space and time.
Trajectories are started every six hours.
DIFFUSIVE METHOD?
The continuous emission source is modeled as
a series of instantaneous "puffs". Each puff is advected
along the trajectory and sampled a few times daily.
The concentrations at the receptors are calculated by
the Gaussian equation for an instantaneous source. Here
the vertical standard deviation is the square root of
2 K t, where K is the vertical diffusivity, and the
horizontal standard deviation is assumed to be .5 t
where t is the travel time in seconds.
60
-------
SPECIES
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH?
The model is organized to compute concentrations
at receptors within one or two days travel time of the the
source.
RESOLUTION AND EXTENT OF TIME INCREMENT?
The recommended time increment is 3 hours with
the extent of a run limited only by the availability of
input data and computation time.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
BACKGROUND DATA? None.
MULTIPLE SPECIES? No.
WHICH REACTIVE SPECIES? None.
WHICH NON-REACTIVE SPECIES? S02,TSP,etc.
DEPOSITION? No.
DECAY? No.
CHEMISTRY? No.
COMPUTED DATA:
AVERAGES? Yes.
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Yes.
3 HOUR? Yes.
24 HOUR? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? Yes.
VALIDATION HISTORY? Limited: Heffter et al.,1975.
There are current plans for extensive study during the
coming year.
APPLICABLE TO FOUR CORNERS REGION?
A higher resolution, numerical model would
be more appropriate for short-term events in the
Four Corners region.
INCORPORATION OF OBSERVED DATA? In principle,yes.
CALIBRATION POTENTIAL? Not ascertained.
61
-------
USAGE CRITERIA:
USER'S MANUAL? No external documentation.
AVAILABILITY OF THE MODEL? In the public domain.
EASE OF MODIFYING MODEL? Dependent on documentation.
EASE OF USING MODEL? Relatively easy.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Moderate.
ERROR DIAGNOSTICS? Minimal.
EASE OF MODEL INSTALLATION ON UNIVAC? ???
EASE OF MODEL MAINTENANCE? Dependent on documentation.
OUTPUT INTERPRETATION REQUIREMENTS? Minor.
OPERATION:
CORE REQUIREMENTS? Not ascertained.
ON LINE STORAGE REQUIREMENTS? Not ascertained.
COMPUTATIONAL TIME REQUIREMENTS? Not ascertained.
INPUT DATA PREPARATION TIME REQUIREMENTS? Not ascertained
REFERENCES FOR HEFFTER-TAYLOR-FERBER SHORT-TERM MODEL:
Heffter J.L., Taylor A.D., Ferber G.J.,1975:"A
Regional-Continental Scale Transport, Diffusion, and Deposition
Model", NOAA Technical Memorandum ERL ARL-50
Heffter J . L . ,1965:"The Variation of Horizontal Diffusion
Parameters with Time for Travel Periods of One Hour or Longer",
J.A.M. Vol 4 , pp 153-156
Machta L,Ferber G. J., and Heffter J.L., 1974:"Regional and Global
Scale Dispersion of Krypton-85 for Population-Dose
Calculations",Proc. Symposium on the Physical Behavior of
Radioactive Contaminants in the Atmosphere,IAEA,Vienna,pp 411-425
15. SHEIH-MOROZ MODEL
This is a Lagrangian puff model that takes into account
temporal and spatial inhomogeneity, notably wind shear;
integrates plume-rise calculation into the puff model; and can
optimally tailor its Lagrangian coordinates to the need of the
multi-scale sources of urban modeling. It can be used to provide
treatment of sub-grid scale phenomena in regional scale grid
models .
The plume from a point, line, or area source is treated as
a series of puffs emitted successively from the specific source.
Each of the puffs is characterized by the amount of pollutant
emitted and by the coordinates of three axes and, for the case
62
-------
where buoyant plume rise is important, the temperature and
vertical velocity of the puff. At each time step, the position of
the three axes are computed from local variables taking into
account advection, eddy diffusion, wind shear, and plume-rise
entrainment.
The concentration distribution within each puff is
determined by fitting an ellipsoid around the axes and assuming a
Gaussian distribution with the length of the principal axes of
the ellipsoid as standard deviations. The final concentration at
a point of interest is obtained by summing the contributions from
nearby puffs.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Yes.
SINGLE STATION? Yes.
GRIDDED INPUT? In principle, yes.
ARBITRARY STATION INPUT? In principle, yes.
SPATIAL EXTRAPOLATION TECHNIQUE? Not ascertained
INPUT TIME INTERVAL? Not ascertained
MIXING LID:
INPUT SPATIAL REQUIREMENT? Not ascertained.
SPATIAL EXTRAPOLATION? Not ascertained.
INPUT TEMPORAL REQUIREMENT? Not ascertained.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Diffusivity.
INPUT SPATIAL REQUIREMENT? Constant.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? Yes.
AMBIENT TEMPERATURE? Yes.
AMBIENT PRESSURE? Yes.
PRECIPITATION RATE? No.
SOLAR RADIATION? No.
SURFACE HEAT FLUXES? No.
EMISSIONS:
SOURCE INVENTORY:
63
-------
ELEVATED SOURCES? Yes.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? ???
TIME DEPENDENT SOURCE STRENGTHS? No.
INSTANTANEOUS SOURCE EMISSIONS? Yes.
PLUME RISE? Yes.
BUOYANT ENTRAINMENT? Yes.
Buoyancy entrainment is incorporated
into the puff motion by an iterative solution to
the conservation laws of volume, momentum, and heat
of an instantaneous source (eg, Morton et al.) for the
puff radius.
VERTICAL WIND SHEAR? Yes.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? In principle, yes.
POLAR GRID? In principle, yes.
ARBITRARY LOCATIONS? In principle, yes.
TERRAIN? No.
TRANSPORT:
ADVECTIVE METHOD?
The plumes are modeled as a series of puffs
represented by 8 Lagrangian particles. The first
six particles are for translation and the last two
for wind shear rotation.
At each time step the first six particles
are displaced an amount u dt where dt is the time
step and u is the three dimensional wind vector.
In addition, during the first time interval of
release, the particle advection takes account of
the stretching of the puff due to the difference
in exposure time of the various parts of the puff
to the advection wind.
Wind shear rotation about the vertical axis
is neglected. Rotation about the horizontal axes
is incorporated by a displacement proportial to
the variation of the wind field over the puff.
DIFFUSIVE METHOD?
The Lagrangian particles are also displaced by a
diffusive velocity estimated from the Gaussian puff
diffusion equation given by Sutton. This velocity is the
square root of 2 K/2 t, where K is the diffusivity
is the relevant direction and t is the time from
-------
SPECIES
release.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH? Not ascertained.
RESOLUTION AND EXTENT OF TIME INCREMENT? Not ascertained
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
MULTIPLE SPECIES? No.
WHICH REACTIVE SPECIES? None.
WHICH NON-REACTIVE SPECIES? S02
DEPOSITION? No.
DECAY? No.
CHEMISTRY? No.
COMPUTED DATA:
AVERAGES? Yes.
LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Yes.
3 HOUR? Yes.
24 HOUR? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? No.
VALIDATION HISTORY?
Comparison of plume with TVA observation, Sheih and
Moroz, "A Lagrangian Puff Diffusion Model for the Prediction
of Pollutant Concentrations over Urban Areas", (1973)
APPLICABLE TO FOUR CORNERS REGION? Not in isolation; see
Section 16.
INCORPORATION OF OBSERVED DATA? Not ascertained.
CALIBRATION POTENTIAL? Not ascertained.
USAGE CRITERIA:
USER'S MANUAL? No external documentation.
AVAILABILITY OF THE MODEL? Developmental
EASE OF MODIFYING MODEL? Unknown.
EASE OF USING MODEL? Unknown.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Unknown
ERROR DIAGNOSTICS? Unknown.
EASE OF MODEL INSTALLATION ON UNIVAC? Unknown.
65
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EASE OF MODEL MAINTENANCE? Unknown.
OUTPUT INTERPRETATION REQUIREMENTS? Unknown.
OPERATION:
CORE REQUIREMENTS? Not presently known.
ON LINE STORAGE REQUIREMENTS? Not presently known.
COMPUTATIONAL TIME REQUIREMENTS? Not presently known.
INPUT DATA PREPARATION TIME REQUIREMENTS? Not presently
known
REFERENCES:
Morton B. R.
gravitational
sources'
Taylor G.I.,
convectin from
of the Roy. Soc.
Turner J.
maintained
234 pp 1-23
S.,1953:"Turbulent
and instantaneous
Proc.
Sutton, 0. G. ,1953: Micrometerology, p 131*, Me Graw -Hill,NY
Sheih.C.M.
for the
Moroz , W . J
Prediction
Areas.
Proc.
FDR,VDI-Verlag,
,1973'-"A Lagrangian Puff Diffusion Model
of Pollutant Concentrations over Urban
Third Inter. Clean Air Congress, Dusseldorf,
B43-B52
16. SHEIH PUFF-GRID MODEL
This is a mesoscale model combining a Lagrangian puff
model (see Section 15) with a particle-in-cell grid model. The
puff model is used to handle sub-grid scale phenomena. The
pollutant in each puff is passed to the grid system and
henceforth is treated with the grid model after the puff has
grown to a size comparable with the grid volume. Area sources
comparable with or larger than the grid dimension are treated
with the grid model. The final concentration at a point of
interest is obtained by summing the contributions from the grid
model and nearby puffs.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Yes.
SINGLE STATION? Yes.
GRIDDED INPUT? No.
ARBITRARY STATION INPUT? Mo.
SPATIAL EXTRAPOLATION TECHNIQUE? None.
66
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INPUT TIME INTERVAL? Hourly.
DIVERGENCE FREE? Yes.
SMOOTHING? No.
ADJUSTED FOR MIXING LID? No.
MIXING LID: None.
TURBULENCE DATA:
DIFFUSIVITY OR STABILITY? Diffusivity
INPUT SPATIAL REQUIREMENT? Constant.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? Yes.
AMBIENT TEMPERATURE? Yes.
AMBIENT PRESSURE? Yes.
PRECIPITATION RATE? No.
SOLAR RADIATION? No.
SURFACE HEAT FLUXES? No.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? Yes.
AREA SOURCES? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? Yes
INSTANTANEOUS SOURCE EMISSIONS? Yes.
PLUME RISE? Yes
BUOYANT
by an iterative
of conservation
VERTICAL
ENTRAINMENT? Yes.
Buoyancy entrainment is modeled
numerical solution to the equations
of volume, momentum, and heat.
WIND SHEAR? Yes.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No
TERRAIN? No.
67
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TRANSPORT:
ADVECTJVE METHOD?
DIFFUSIVE METHOD?
The plume from a source small in comparison
to the grid dimension is modeled as a series of puffs, with
the shape of each puff determined by 6 Lagrangian particles.
At each time step the particles are advected by the local
wind field, with displacements due to wind shear and buoyancy
entrainment and due to a diffusive velocity. When the puff
and grid dimension are comparable, the puff is merged with the
grid particles.
The grid scale advection solves the conservation
of mass equation by the particle-in-cell method. Briefly, this
method assumes that the total pollutant in each grid cell is
concentrated in a single particle at the grid center. In each
time step the particle is displaced to a new location by the
sum of advective and diffusive velocities multiplied by the
time increment. Upon reaching another location, the pollutant
in the particle is then redistributed to the. surrounding grid
points, inversely weighting the mass distribution according
to distance.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? Yes.
SPATIAL RESOLUTION AND EXTENT OF MESH?
The model covers a 5 km by 5 km area
with an 11 by 11 horizontal grid and 11 levels from the
surface up to a height of 1 km.
RESOLUTION AND EXTENT OF TIME INCREMENT? 30 Sec. for 24 hr
BOUNDARY CONDITIONS?
No pollutant deposited on the ground, all
grid and puff pollutants are removed from the field after
they are transported out of the region of interest.
INITIAL CONDITIONS? Initial S02 field is 0.
NUMBER OF VERTICAL LAYERS? 11
BACKGROUND DATA? No.
SPECIES
MULTIPLE SPECIES? No.
WHICH REACTIVE SPECIES? None.
WHICH NON-REACTIVE SPECIES? S02
DEPOSITION? No.
DECAY? No.
CHEMISTRY? No.
COMPUTED DATA:
AVERAGES? Yes.
68
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LONG TERM(ANNUAL)? No.
SHORT TERM? Yes.
1 HOUR? Yes.
3 HOUR? Yes.
24 HOUR? Yes.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? No.
VALIDATION HISTORY?
Comparison of observed and prediction over State
College, Pa: "A Puff-Grid Model for Predicting Pollutant
Transport Over an Urban Area", C.M. Sheih (1976)
APPLICABLE TO FOUR CORNERS REGION?
If suitably modified, yes.
INCORPORATION OF OBSERVED DATA? Not ascertained.
CALIBRATION POTENTIAL? Not ascertained.
USAGE CRITERIA:
USER'S MANUAL? Lacks basic documentation.
AVAILABILITY OF THE MODEL? Developmental.
EASE OF MODIFYING MODEL? Depends on documentation.
EASE OF USING MODEL? Depends on documentation.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Unknown.
ERROR DIAGNOSTICS? Unknown.
EASE OF MODEL INSTALLATION ON UNIVAC? Depends on documentation.
EASE OF MODEL MAINTENANCE? Depends on documentation.
OUTPUT INTERPRETATION REQUIREMENTS? Unknown.
OPERATION:
CORE REQUIREMENTS? Unknown.
ON LINE STORAGE REQUIREMENTS? Unknown.
COMPUTATIONAL TIME REQUIREMENTS? 500 sec. for 24 hours, IBM 370
INPUT DATA PREPARATION TIME REQUIREMENTS? Unknown.
REFERENCES:
Sheih C. M. and Moroz W. J.,1973:"A Lagrangian Puff Diffusion
Model for the Prediction of Pollutant Concentrations over Urban
Areas", Proc. The Third International Clean Air Congress, B43-B52
Sklarew, R. C.,1970:"Preliminary Report of the SSS Urban Air
Pollution Model Simulation of Carbon Monoxide in Los Angeles",
System,Science, and Software, Inc. La Jolla, California
Sklarew, R.C. , "A New Approach: The Grid Model of1 Urban Air
Pollution", JAPCA, 20, p 79 (1970)
69
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17. BNL TRAJECTORY MODEL
This model is the Heffter, Taylor and Ferber model
modified by the BNL Meteorology Group to include chemical
transformations and deposition. The model was furthur modified to
consider multiple sources by combining their individual sulfur
dioxide and sulfate patterns for the time period modeled.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? Vertically averaged winds.
SINGLE STATION? Yes.
GRIDDED INPUT? Yes (analyzed).
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
This models computes grid point winds
from station winds by weighting the observations
of all stations within a radius R by distance and
alignment. While the user may select various
parameter values, the model is set up for a radius
R=300 nautical miles and for a distance weighting
factor of 1/r**2 and an alignment weighting factor
of 1-.5 abs(sin(a)) if r is the distance to the
station and a its angle relative to the wind at a.
The model uses a bilinear interpolation
from corner grid points to the interior of a cell.
INPUT TIME INTERVAL? 12 hours or 6 hours.
TEMPORAL INTERPOLATION TECHNIQUE?
The model assumes persistence of the
winds reported closest to the calculation time.
(No trajectory is calculated if the wind data
is missing for the 2 or 3 closest time periods.) •
DIVERGENCE FREE? No.
SMOOTHING? If analyzed.
ADJUSTED FOR MIXING LID? Vertically averaged.
MIXING LID:
INPUT SPATIAL REQUIREMENT? Uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
TURBULENCE DATA:
70
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DIFFUSIVITY OR STABILITY? Diffusivity,
INPUT SPATIAL REQUIREMENT? Constant.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Constant.
TEMPORAL INTERPOLATION? None.
OTHER METEOROLOGICAL DATA? Yes.
AMBIENT TEMPERATURE? No.
AMBIENT PRESSURE? No.
PRECIPITATION RATE? Yes.
SOLAR RADIATION? No.
SURFACE HEAT FLUXES? No.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? No.
AREA SOURCES? No.
MULTIPLE STACKS AT ONE SITE? Yes.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS? No
INSTANTANEOUS SOURCE EMISSIONS? No.
PLUME RISE? No
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? No
TERRAIN? No.
TRANSPORT:
ADVECTIVE METHOD?
This model computes trajectories for up to 10 days
using U dt increments where dt=3 hours and U is the
computed wind at the current point in space and time.
Trajectories are started every six hours.
DIFFUSIVE METHOD?
Ground-level air concentration calculations
along a trajectory are based on the Gaussian plume
equation for a continuous point source assumed to be
at ground level. The plume is modeled as a series of
plume segments (or "puff-slices") each with a downwind
length of U dt, where U is the mean wind speed and dt
is the time increment.
71
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The standard deviation of the plume's mass
normal to the wind direction is assumed to be propor-
tional to the travel time, t, and the vertical standard
deviation is equal to the square root of 2 K t, where
K is the diffusivity.
HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? No.
SPATIAL RESOLUTION AND EXTENT OF MESH?
The model is organized to compute on a large
scale grid of about 80 by 80 in extent with a spacing
of .5 degrees in latitude or longitude.
RESOLUTION AND EXTENT OF TIME INCREMENT?
Intended for monthly, seasonal applications
with a time increment of 3 hours.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
BACKGROUND DATA? None.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? S02.SOU
WHICH NON-REACTIVE SPECIES? S02,TSP,etc.
DEPOSITION? Yes.
WET?
Precipitation scavenging is based
on an empirically derived average scavenging
ratio (Engelmann,1970).
DRY?
The concept of deposition velocity is
used to calculate dry deposition amounts along
a trajectory for both S02 and S04.
DECAY? No.
CHEMISTRY?
Linear chemistry is used to convert S02 to SOM
along a trajectory. The conversion rate is a parameter
In addition 2% of the initial S02 is immediately con-
verted to S04 to simulate in-stack production of S04.
COMPUTED DATA:
AVERAGES? Yes.
72
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LONG TERM(ANNUAL)? Yes.
SHORT TERM? No.
MAXIMUM CONCENTRATIONS? No.
PLUME TRAJECTORY? Yes.
VALIDATION HISTORY? Limited: Heffter et al.,1975
APPLICABLE TO FOUR CORNERS REGION?
Yes, if suitably modified.
INCORPORATION OF OBSERVED DATA? Not ascertained
CALIBRATION POTENTIAL? Not ascertained.
USAGE CRITERIA:
USER'S MANUAL? None.
AVAILABILITY OF THE MODEL? Not presently available.
EASE OF MODIFYING MODEL? Not now ascertained.
EASE OF USING MODEL? Not now ascertained.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Unknown.
ERROR DIAGNOSTICS? Not now ascertained.
EASE OF MODEL INSTALLATION ON UNIVAC? Not now ascertained.
EASE OF MODEL MAINTENANCE? Not now ascertained.
OUTPUT INTERPRETATION REQUIREMENTS? Minor.
OPERATION:
CORE REQUIREMENTS? Not now ascertained.
ON LINE STORAGE REQUIREMENTS? Not now ascertained.
COMPUTATIONAL TIME REQUIREMENTS? Not now ascertained.
INPUT DATA PREPARATION TIME REQUIREMENTS? Not now ascertained
REFERENCES:
Heffter J.L., Taylor A.D., Ferber G.J.,1975:"A
Regional-Continental Scale Transport, Diffusion, and Deposition
Model", NOAA Technical Memorandum ERL ARL-50
Englemann R . J.,1970:"Scavenging Prediction Using Ratios of
Concentrations in Air and Precipitation",Proc. Symposium on
Precipitation Scavenging, AEC Symposium Series 22, pp 475-485
Heffter, J.L.,1965:"The Variation of Horizontal Diffusion
Parameters with Time for Travel Periods of one Hour or Longer",
J.A.M. Vol 4 , pp 153-156
Machta, L,Ferber, G. J., and Heffter J.L.,,1974:"Regional and
Global Scale Dispersion of Krypton-85 for Population-Dose
Calculations",Proc. Symposium on the Physical Behavior of
Radioactive Contaminants in the Atmosphere,IAEA,Vienna,pp 411-425
73
-------
Meyers, R. and R. Cederwall, 1975: BNL RESP Annual Report, BNL
50478
18. STRAM MODEL
STRAM (Source-Transport-Receptor Analysis Model) is basically a
version of the Gaussian Plume Model modified to account for
temporal variations in point source emission rates and both
spatial and temporal variations in wind speed, wind direction and
plume dispersion parameters. The model formulation also allows
for dry deposition, washout and chemical transformation. Although
the model is described as being able to treat non-linesr
chemistry, there is the implicit assumption that each chemical
species involved in the reaction is emitted from a single source
so that the chemical kinetics associated with interacting plumes
is ignored. In fact, for the example test case presented in the
User's Manual, only the first order transformation of S02 to
sulfate is analyzed.
The basic driving force in the model is the advection of plume
increments (points) in response to a wind field updated at
specified intervals. A plume segment is defined to be a portion
of the plume between successive plume increments. The wind field
is derived from pibal and rawinsonde data reduced from ETAC upper
air data tapes. These data are then processed by the program
RNGRD (Random-to-Grid) to obtain gridded wind directions and wind
speeds at 12-hour intervals. The gridded wind field is generated
from measured wind speeds and wind directions by use of a inverse
distance squared weighting procedure. The wind field is adjusted
for the mixing height but not smoothed or divergence free. The
wind speed and wind direction for a particular plume increment is
obtained through a bi-linear interpolation of the gridded wind
field in space and time. Since ETAC upper air data is used for
the wind field generation, both the advection and sampling grid
systems must be subsets of the NMC 47 by 47 octagonal grid
system. Present dimensions of the code allow for an advection
grid with not more than 17 intersections in the horizontal
direction of the NMC grid and not more than 13 intersections in
the vertical direction. The sampling grid is currently limited to
13 by 13 equally spaced intersections. The program also allows
for concentrations to be computed for up to 10 special receptor
locations.
After each advection step for a plume increment, a numerical
calculation is performed to determine the amount of a chemical
constituent lost or gained during the advection time due to
chemical transformation, dry deposition and washout. To carry out
this calculation of a new effective source strength, the
74
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advection distance is subdivided according to program input
specifications. Since chemical transformations generally occur at
a higher rate for shorter downwind distances the model provides
for successively larger integration step sizes for those plume
segments located at larger downwind distances from the source.
For each downwind integration step, the calculation of the gain
or loss of a substance due to chemical transformation requires an
integration over the y and z coordinates perpendicular to the
plume axis.
In addition to updating the wind speed and effective source
strength at each plume increment, the vertical and horizontal
dispersion parameters are increased by an amount depending upon
the advection distance and the stability class in force at the
appropriate simulation time. Concentrations are then calculated
at each of the plume increment points and at three equally spaced
points at either side of the plume increment points along lines
perpendicular to the plume segment axis. The calculation points
are spaced so that the distance between the extreme points (plume
"width") is six times the horizontal dispersion parameter. For
each plume segment each of the sampling grid points and special
sampling locations are examined to determine whether they lie
within a trapezoid defined by the plume widths at adjacent plume
increments and the straight lines connecting the end points of
these widths. If the sampling point is found to lie within this
region, then the concentration for this location is obtained
through an interpolation of the appropriate crosswind
concentrations for the plume increment points at the opposite
ends of the plume segment.
FUNCTIONAL CRITERIA:
METEOROLOGY:
WIND FIELD:
VERTICAL RESOLUTION? None.
GRIDDED INPUT? Yes, after running the
meteorological preprocessor program RNGRD
(Random-to-Grid).
ARBITRARY STATION INPUT? Yes.
SPATIAL EXTRAPOLATION TECHNIQUE?
1/r**2 extrapolation to grid points, linear
interpolation from grid points to plume
increments.
INPUT TIME INTERVAL? Variable.
TEMPORAL INTERPOLATION TECHNIQUE? Linear.
DIVERGENCE FREE? No.
SMOOTHING? No.
ADJUSTED FOR MIXING LID? Yes, if the limited
mixing height for of the Gaussian plume model is
75
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specified.
MIXING LID:
INPUT SPATIAL REQUIREMENT? Uniform in space.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly or at each
advection step.
TEMPORAL INTERPOLATION? Persistence.
TURBULENCE DATA: Stability Class
DIFFUSIVITY OR STABILITY? Stability.
INPUT SPATIAL REQUIREMENT? Uniform.
SPATIAL EXTRAPOLATION? None.
INPUT TEMPORAL REQUIREMENT? Hourly or at each
advection step.
TEMPORAL INTERPOLATION? Persistence.
OTHER METEOROLOGICAL DATA? None.
EMISSIONS:
SOURCE INVENTORY:
ELEVATED SOURCES? Yes.
AREA SOURCES? No.
MULTIPLE SOURCE SITES? Yes.
TIME DEPENDENT SOURCE STRENGTHS?
INSTANTANEOUS SOURCE EMISSIONS?
Yes
Yes.
PLUME RISE? No.
RECEPTOR GEOMETRY:
RECTANGULAR GRID? Yes.
POLAR GRID? No.
ARBITRARY LOCATIONS? Yes, up to ten.
TERRAIN? No.
TRANSPORT
ADVECTIVE METHOD? Simple Euler integration.
DIFFUSIVE METHOD? The vertical and horizontal plume
standard deviations at each plume increment point are
based upon the total distance traveled and the current
stability class, as well as the accumulated sigmas
acquired thus far.
76
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HORIZONTAL DIFFUSION? Yes.
VERTICAL DIFFUSION? Yes.
PSEUDO-DIFFUSION? None.
SPATIAL RESOLUTION AND EXTENT OF MESH? STRAM has an
advection grid with 17 intersections in the horizontal
direction and 13 intersections in the vertical. The
advection grid must be a subset of the NMC grid.
RESOLUTION AND EXTENT OF TIME INCREMENT? The number of
hours for each basic advection step is a user input
variable.
BOUNDARY CONDITIONS? None.
INITIAL CONDITIONS? None.
NUMBER OF VERTICAL LAYERS? None.
BACKGROUND DATA? Yes.
SPECIES:
MULTIPLE SPECIES? Yes.
WHICH REACTIVE SPECIES? Any for which the
reaction rates can be specified.
WHICH NON-REACTIVE SPECIES? Any.
DEPOSITION? Yes.
WET?
DRY?
DECAY? Yes.
CHEMISTRY? No problem with linear chemistry, but if
non-linear chemistry is invoked, the effects of
interacting plumes may not be included.
COMPUTED DATA:
AVERAGES? Yes. (Non-overlapping)
LONG TERM(ANNUAL)? Yes.
SHORT TERM? Yes.
1 HOUR?
3 HOUR?
2M HOUR?
MAXIMUM CONCENTRATIONS? Yes.
PLUME TRAJECTORY? Currently not printed out but an easy
modification.
VALIDATION HISTORY? None.
APPLICABLE TO FOUR CORNERS REGION? The model is, with the
necessary modifications, applicable to the Four Corners
region.
INCORPORATION OF OBSERVED DATA? No.
CALIBRATION POTENTIAL? Good, given adequate observed
data .
USEAGE CRITERIA:
77
-------
USER'S MANUAL? Very detailed and user oriented (well flow
charted).
AVAILABILITY OF THE MODEL? In the public domain.
EASE OF MODIFYING MODEL? The code is broken down into a number of
subroutines which deal with separate model functions, so that
modifications to the model can be made with little disruption
to the structures of the entire code. Changes in deposition and
chemical kinetics parameters must be made within the code itself.
EASE OF USING MODEL? Relatively easy, given meteorological data.
VOLUME OF DATA REQUIRING MANUAL PREPARATION? Moderate.
ERROR DIAGNOSTICS? Good.
QUALITY ASSURANCE?
EASE OF MODEL INSTALLATION ON UNIVAC? Presently in process of
being setup to run on the UNIVAC 110.
EASE OF MODEL MAINTANANCE? Relatively easy.
OUTPUT INTERPRETATION REQUIREMENTS? Average.
OPERATION:
CORE REQUIREMENTS? 176K bytes (for 6 chemical constituents).
ON LINE STORAGE REQUIREMENTS? None.
COMPUTATIONAL TIME REQUIREMENTS? No timing information available.
Would depend upon number of chemical species, sources and plume
increments.
INPUT DATA PREPARATION TIME REQUIREMENTS? M hours.
OTHER HARD WARE REQUIREMENTS? 2 tape drives.
REFERENCES FOR STRAM MODEL:
Hales, J. M., Powell, D.C., and T.D. Fox, 1977, "STRAM - An Air
Pollution Model Incorporating Non-linear Chemistry, Variable
Trajectories and Plume Segment Diffusion", EPA-450/3-77-012.
78
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
2.
3. RECIPIENT'S ACCESSIOI*NO.
4. TITLE AND SUBTITLE
5. REPORT DATE
A REVIEW OF REGIONAL-SCALE AIR QUALITY MODELS FOR LONG
DISTANCE DISPERSION MODELING IN THE FOUR CORNERS REGIOIf
October 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
John A. Nuber, Arthur Bass, Michael T. Mills, and
Charles S. Morris
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Research & Technology, Inc
696 Virginia Road
Concord, MA 01742
10. PROGRAM ELEMENT NO.
EHE 625 C
11. CONTRACT/GRANT NO.
03-6-02-35254/NOAA Contract
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
13. TYPE OF REPORT AND PERIOD COVERED
Contract Report
14. SPONSORING AGENCY CODE
EPA-600/7
15. SUPPLEMENTARY NOTES
Performed under contract to the National Oceanic and Atmospheric Administration
16. ABSTRACT
A review of available long-range air quality transport and diffusion models has
been prepared to select, modify, and apply such a model for the simulation of
air quality impact associated with emissions from new energy resource development
in the Four Corners area of the Western United States. Primary emphasis has been
placed upon the review of models that are presently operational and currently
available for use and adaptation.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
*Air Pollution
*Reviews
*Atmospheric Diffusion
*Transport properties
13B
05B
07D
14B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
82
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
. GOVERNMENT PRINTING OFFICE: 1978-0-777-167/1259
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