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Introduction toair pollution modeling with
SoundPLAN Air Pollution Modules
Braunstein + Berndt GmbH
SoundPLAN International LLC
80 E Aspley Lane
Shelton, WA 98584
Your local distributor:
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Results of air pollution calculations use a lot of disk
space, making it impossible to create a small demo
project with sensible in- and output for all the Air-
PLAN models and modules. Users want to save time,
too, so they will also simplify project data. Our
demo shows what SoundPLAN does, how to use it,
and how to correctly simplify projects.
Demo projects are stored on our FTP server with
slides and a short project description and a sum-
mary of the results. Download projects and analyze
how we have accomplished different tasks.
Open SoundPLAN in the demo mode in order to have
all air pollution modules available. In this mode you
can do everything except store files. For more exten-sive investigations, order a temporary trial license
from your local distributor. Distributor information is
found at www.soundplan.com.
Rough Estimation or Detailed Analysis?
Remember the three levels of investigation when you begin modeling:
Prediction Dontbe fooled by the illusion that air pollution concentrations can
be exactly foreseen if you were to buy the right calculation model. Such a model
would be too complex to even start from a PC! You will discover that it is nearly
impossible to get the complete data needed for a good prognosis. You must
create scenarios based on a few estimations instead of the many local mea-
surements actually needed for precise work. This makes sense when you con-
sider that forecasting air pollution concentrations cant be easier thanforecast-
ing weather because air pollution dispersion depends, in part, on weather con-
Detailed analysis(we call it, fine screening) allows you to simplify a model as
much as needed. However, all that is gained from a simplified scenario is a good
estimation of concentrations. How accurate can a detailed analysis be? You
have to combine complex wind fields and dispersion conditions with a reliable
emission scenario. What if the scenario doesnt work? Is there a simpler way to
get reliable results? Of course! Rough estimation!
Rough estimation(or, rough screening) seems a simple task to beginners who
have unreliable results, but this is not true! Experienced users carefully refine
their tasks and choose rough estimation methods to save calculation time and
win reliability and accuracy. They simplify models in ways that guarantee mod-
erate, but secure overestimations. Using a rough screening model correctly, is
simply not as easy as it seems! Thoughtfully operating outside the borders of
reality requires a lot of skill to read reliable information from the results.
Willlimit values be exceeded?
is a difficult question to answer, even
using a fine screening model for de-
The answer yesor norequires
evaluating the probability of error.
This value can be estimated for
measurement based validation
calculations, but not for estima-
tions based on freely defined sce-
Canexceeded limits be excluded?
is easily answered. A rough estimationis needed for a definitive no answer.
The answer yesis based on a
specific overestimation, so it is re-
liable. Nois not reliable. It re-
quires either an alternate plan or
refinement of input data and finer
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Rough screening: Gauss(TA Luft86) | 3
(German national standard TA Luft 1986-2002)
Gauss was part of the official German standard "TA Luft
86" which was released to estimate the impact of new
industrial air pollution sources, especially high emitting
point sources like smoke stacks. It is a simplified version of
the Gauss model defined in the VDI code3782-1. The vali-
dation is associated to the evaluation of the VDI standard.
It has a tendency to overestimate close to the source.
Gauss models calculate very quickly. That means they can,
and should, handle wind statistics with a very high resolu-
tion. They calculate a plume with a statistical pollutant
distribution for each wind flow situation before evaluating
statistics like mean, max and percentiles.
The German model is not very sophisticated, but it brings
solid results at least for comparable climate zones. We
suggest looking for test data to compare if it fits your re-
gional conditions and requirements.
Because Gauss models are statistical models, use them
only to analyze representative time periods. Dont use
them for single case interpretations.
Rough screening: Austal2000
(German standard TA Luftsince 2002)
In 2002, TA Luft02, which favors a diagnostic wind field
and a Lagrange model to calculate the air pollution disper-
sion, replaced TA Luft 86. The reference model AUS-
Dr. Janicke, Dunum, Germany) was developed
for the German Environmental Agency.
AUSTAL2000 has three advantages:
It calculates a wind field which can regard terrain up to
an inclination of 20%
It has the reputation of the German government
It is freeware; you pay only for the SoundPLAN inter-
Austal2000 is very rudimentary, based on ASCII-input-textfiles and ASCII-output-text files. The SoundPLAN interface
allows you to work in a comfortable program environment.
You can apply your experience with the SoundPLAN Libra-
ries, Geodatabase, Calculation Kernel and Graphics, plus
you have full SoundPLAN support for the interface.
Working with freeware does have some disadvantages:
There is no international support for the original AUS-
TAL2000 calculation kernel. SoundPLAN supports you as
much as possible, but as we are not the authors of
AUSTAL2000, our help is limited to our interface.
You have no claim on reparations if AUSTAL2000 doesnot work or produces implausible results.
The results are limited to the German/European require-
ments. If your national standards are more restrictive or
require additional statistics, Austal2000 isnt suitable.
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4 |Fine Screening: MISKAM
When we talk about fine screening, we talk first about calculating wind fields which can include turbulent
effects between buildings. Then we talk about the spreading based on these precalculated wind fields. That
means we need three dimensional grids with high resolution in x, y, AND z directions, which are calculated
from the ground to a height far above the rooftops. MISKAM and AUSTAL2000 have different wind field
models and also different pollution dispersion equations and are therefore used for different prognosis.
MISKAM(Dr. Eichhorn, University of Mainz, Germany)is a fine screening model with a respected international reputation. The
model was carefully verified and validated while revising the code. The
test calculations are mainly oriented to the guidelines of the VDI-Code
3783/9, Environmental meteorology - Prognostic microscale wind field
models - Evaluation for flow around buildings and obstacles.
Prognostic wind fields solve the physical equations describing the tur-
bulent wind flow instead of matching physics with empirical assump-
tions as do the diagnostic models. This precision consumes a lot of
time! Most highly developed CFD-programs are too oversized for a
common planning job. They require a lot of input not available for an
environmental impact study, because they are made for research or
To find the best compromise between the quality of prognosis of a CFD
program and the time budget of a common planning job, MISKAM sets
strict boundaries for its application scope: The turbulences caused by
obstacles should be so dominant that thermal and terrain effects can
MISKAMdoes not regard terrain and is best used with neutral atmos-
pheric stability. Calculating in stable conditions is possible, but requires
much more calculation time. Unstable conditions are automatically set
to neutral stability. If your investigation area allows these restrictions,MISKAMis one of the best models you can use!
If you are not a meteorological expert, MISKAM's scope of application
should be restricted to inner city simulations like street canyons, park-
ing lots or situations where pollution sources are located close to the
recipients and where local changes of wind speed and turbulence have
to be regarded in a very high resolution. MISKAMis used for hot spots,
not for entire cities!
MISKAM allows simplifications: It is not necessary to calculate with
high resolved wind statistics, because the building structures cause
canalization effects. Also, it is not sensible to calculate with ann