Overview - SPECTRA · Calculation Models - Overview 2 ... in the calculation area and already well...
Transcript of Overview - SPECTRA · Calculation Models - Overview 2 ... in the calculation area and already well...
Overview
Many planning processes require calcula-
tions for noise emissions and air pollution
dispersion. It is welcome news to hear
SoundPLAN has a uniform software inter-
face for both types of calculations so users
can work efficiently in both areas of exper-
tise.
SoundPLAN air pollution modules build a
comfortable bridge between science and en-
gineering:
Embedding scientific calculation kernels in
the user friendly interface of SoundPLAN
and adding specific tools for data control, da-
ta conversion and result presentation,
SoundPLAN creates an environment for
high efficient air pollution dispersion calcula-
tion, benefitted from over 25 years of noise
programming experience.
Calculation Models - Overview
2
Base Module Air Pollution
The Base Module Air Pollution
generates the environment where
all modules are embedded. Besides
the basic modules for data input,
calculation and result presentation
it contains special air pollution li-
brary tools which are designed to
make your work easy, efficient and
transparent. If you own already a
SoundPLAN license, no matter if it
is for acoustics or air pollution, the
base module is discounted by 50%.
MISKAM advanced – wind field and dispersion model
MISKAM is a prognostic wind field
model completed by an Eulerian
dispersion model. The MISKAM
kernel is mainly designed for highly
resolved street canyons (1-2 m) in
dense built areas. For coarser grid
spaces we recommend GRAL.
Those two models complete each
other in a most sensible way.
The established, highly recom-
mended and steadily validated
model MISKAM is ideal for detailed
studies, when air movements
around buildings suppress stronger
thermal effects (neutral atmos-
phere). Stable atmosphere can also
be calculated for single case stud-
ies (worst case studies).
In opposite to former versions of
the SoundPLAN MISKAM interface
MISKAM advanced provides addi-
tionally underflow of buildings,
flow-through of vegetation and a
64 bit version.
The former, slim version is still
maintained for customers owning
a continuous maintenance con-
tract, but only the complete ver-
sion MISKAM advanced is further
sold.
GRAL system – GRAL dispersion model
GRAL system contains of two pro-
grams. GRAL is a highly recom-
mended Austrian Lagrange particle
dispersion model. To adjust the
GRAL wind field to the terrain and
landuse effects, the program
GRAMM is used as meteorological
preprocessor.
GRAL calculates as well for meso-
scale as for microscale tasks. It is
suitable to include traffic sources
in street canyons.
The microscale calculations are not
as precise as those of MISKAM, but
as soon as the borders of MISKAM
are exceeded, e.g. by project size,
atmospheric conditions, terrain
shape, grid resolution and calcula-
tion time, GRAL is the model to
continue on a larger scale.
GRAL uses optionally a diagnostic
wind field approach or a mixed ap-
proach, which can take explicitly
buildings into account by calculat-
ing a prognostic wind field around
the buildings.
Also tunnel portals can be mo-
deled.
GRAL system will be released in
April 2014.
Calculation Models - Overview
3
GRAL system – GRAMM wind fields
GRAMM was developed to calcu-
late wind fields in the complex to-
pography of the Austrian Alps. It is
capable to regard strongly undu-
lated terrain and differentiated
land use.
As prognostic model it can handle
much more details of topography
and land use than the TALDIA
model delivered with Austal2000.
It also regards cold air flows in a
generalized approach.
However – it is a mesoscale model.
It should not resolve topography in
a too fine resolution because it
won't handle stalls. Obstacles
should be modeled by buildings.
GRAL system will be released in
April 2014.
GaussTA Luft'86 – simple plume model
GaussTA Luft'86 is an "old fashioned"
plume model for quick estimations:
The formulas of the former Ger-
man standard "TA Luft '86" are
suitable for approximate calcula-
tions, e.g. to estimate background
concentrations or to make worst
case studies, whenever free flow
conditions can be assumed around
emission sources.
Even though it is the simplest of
our models, it requires good back-
ground knowledge to understand,
for which situations such a statisti-
cal approach can be used and how
the results must be assessed.
AUSTAL2000 interface – wind field and dispersion model
AUSTAL2000, a Lagrange Particle
dispersion model, replaced the
Gauss module as German national
standard for industry approval in
2002. It is the public domain refer-
ence model of the current German
directive "TA Luft 02".
As it is freeware under GNU li-
cense, it is distributed with the
SoundPLAN interface, completed
by the diagnostic wind field model
TALDIA, which can be used for
smoothly undulated topography,
and VDISP, which calculates the
thermal upstream effects of hot
sources and cooling towers.
The original model input and out-
put of all three programs is ASCII
based and restrictively designed to
fulfill the demands of German di-
rectives.
SoundPLAN adds a user friendly in-
terface because an interface is ur-
gently needed for an efficient use.
Austal2000 mainly supports di-
rective 2008/50/EC. If national
standards require different thresh-
olds or aggregations (e.g. 25 daily
means instead of 35 daily means
for PM10), these are soon availa-
ble: A more flexible kernel version
was just released in March 2014.
The SoundPLAN interface will soon
be adjusted until summer 2014.
Even in the new version, Austal-
2000 doesn't allow multithread-
ing/distributed computing.
Calculation Models - Comparison
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What can you expect from a model?
What does the model expect from you?
Topography
Topography has a big influence on the wind flow. On
one hand it is an obstacle which deflects the wind di-
rection. On the other hand slope inclinations and slope
orientation have a big influence on global radiation
and the energy balance of a surface, so that thermal
flows can be induced.
There are two relevant questions which have im-
portance for the model selection:
Is the wind flow within the investigation area ho-
mogenous or is it disturbed by topographic obsta-
cles inside or outside the area? Homogeneous flow
can mostly be calculated without terrain model.
Is the wind flow within the model area represented
by the meteorological measurement point - in
combination with the model topography?
Is the measurement height above ground appropri-
ate for the model? Chimneys reaching high above a
valley can't be calculated with meteorology meas-
ured on the valley ground.
It is not enough to have a calculation model that can
handle topography. Topography requires high quality
input data for meteorology.
Modeling the influence of topography is the most diffi-
cult work. The first step to solve this problem is to
know, when topography can be ignored.
If the source is high above the ground and the ter-
rain is only smoothly undulated, it can be sensible
to model with flat terrain.
If the influence of topography is homogenous with-
in the calculation area and already well represented
by the meteorological measurement, it can also be
sensible to model flat terrain, even on ground of a
deep valley.
Why should you ignore topography, when it is already
nicely modeled and available from the noise part of
your SoundPLAN project?
Modeling topography is indeed easy within
SoundPLAN, but modeling the air flow above the ter-
rain is something different:
The size of the calculation area must be big enough to
regard all the terrain which is reflected in the meteoro-
logical measurement. In complex terrain it is often
necessary to make local measurement.
How do the models treat topography?
MISKAM calculates without topography. It can be
used for flat or homogeneously inclined areas. As
MISKAM calculation areas are rather small, this is
often no problem. In some cases it can be sensible
to model terrain edges carefully (!) simplified by
buildings. However, regard that MISKAM displays
the result layers parallel to the flat model ground.
Calculation Models - Comparison
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GRAL system can calculate flat or include mesoscale
wind fields calculated with GRAMM - as well for
smoothly undulated as for complex terrain. The use
of GRAMM in complex terrain requires really mete-
orological expert's knowledge, especially to find
sensible measurement locations for meteorology.
We will try to offer trainings and model setup con-
sulting together with the program authors, but set-
ting up difficult projects will not be part of the hot-
line support.
Austal2000 calculates with flat or smoothly undu-
lated terrain up to 20% incline. The result display
layers follow parallel to the terrain heights.
Regard of topography should be handled with care.
Even for smoothly undulated terrain the calculation
area must often be much bigger than the investiga-
tion area. Thermal induced wind flow is not regard-
ed in the model; this might be a problem if e.g. a
cold air flow crosses a part of the investigation area.
GaussTA Luft'86 ignores topography and should
therefore mainly be used for chimneys.
Landuse and buildings
Landuse determines the vertical exchange of air close
to the ground. Obstacles like trees, bushes and build-
ings cause turbulence. This causes on one hand a re-
duction of the mean wind speed or brings chimney pol-
lutants quicker down to the ground; on the other hand
it helps to bring pollutants from the ground to higher
atmosphere layers.
The closer the sources and the annoyed receivers are
located to each other, the more an individual resolu-
tion of those obstacles is sensible.
MISKAM advanced, as microscale model, offers the
most detailed resolution of obstacles. It regards
buildings, underflow of buildings and, if necessary,
even detailed flow through vegetation with differ-
ent layers of leaf density. In the inflow and outflow
area of the model geometries, those obstacles can
be generalized as "roughness areas". Those are are-
as with different roughness parameters which in-
fluence turbulence and wind speed.
GRAL resolves in its microscale mode buildings in
diagnostic or prognostic mode. Land use areas can
be applied by precalculating mesoscale wind fields
with GRAMM. GRAMM derives from landuse areas
roughness length and further parameters like albe-
do etc., which influence the energy balance and lo-
cal wind flow. Defining landuse by the CORINE
landuse classes, GRAL is the most universal model.
Austal2000 with its wind field model TALdia re-
quires a generalized roughness definition for the
whole area, what can be a problem especially for
ground near sources. Buildings can be regarded in a
fine resolution to model the turbulence influence
for low chimneys. The wind flow between complex
building structures is not capable to calculate sensi-
ble results for street canyons. All emission sources
should therefore have a more or less free wind in-
flow. Austal2000 is a reference model for sources
above 1,2 times the average obstacle height with
buildings modeled or 1,7 times above the average
obstacle height if buildings are only regarded by
roughness length.
Calculation Models - Comparison
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Gauss doesn't resolve any landuse parameter. It
just requires free flow conditions around the
source, what is best ensured with high chimneys.
Meteorology
The models use meteorological data in a different way.
MISKAM reads meteo data like wind speed and
wind direction as wind inflow into the area. There-
fore the investigation area must be surrounded by a
400-500 m belt of (generalized) buildings which ad-
justs the wind speed and wind directions to the
building structure before it reaches the investiga-
tion area.
GRAL and GRAMM also read the meteo data as in-
flow data. GRAMM modifies the inflow to repro-
duce the flow at the anemometer station with sev-
eral approaches. The model must hold the physics
within the whole model area consistent. As the to-
pography is clipped by the rectangular calculation
area, influences from outside can be less homoge-
neous than modeled. It depends on both the quality
of measurement and modeling, where in the model
area the wind field can be called representative.
Austal2000 calculates a simple diagnostic standard
wind field and adjusts it to the measured wind
speed at the anemometer station. If the anemome-
ter is well located, this works fine for smoothly un-
dulated terrain. If the weather statistics are meas-
ured outside the area and transposed to an imagi-
nary station within the area, the quality of modeling
decreases commonly with the increase of slope in-
clination.
Gauss takes the flow defined in the meteo statistics
as flow at the source. The wind speed is corrected
by logarithmic wind speed profiles.
Emissions
Worldwide there are lots of different standards to de-
rive emissions, each using completely different source
parameters. Therefore SoundPLAN doesn't calculate
emissions. However, if you assign clear identifiers as
source name to your source objects, you can easily im-
port the emissions from almost free definable, column
oriented ASCII tables.
Most emission models for traffic emission are made
for coarse inventories and they don't have the resolu-
tion to feed a microscale model like MISKAM. For Eu-
rope we intend to connect the Austrian traffic emission
model NEMO to the road sources. It uses the same da-
ta base as the standard HBEFA/MICET, but already
sensibly aggregated for whole roads instead of single
cars. The programming of NEMO and much of the
measurement for HBEFA/MICET is made at the tech-
nical University of Graz. Therefore the NEMO data
base is always a bit quicker updated than
HBEFA/MICET. Maybe it can once become a worldwide
solution.
Calculation results and limit values
Calculations as well as measurement represent stable
values for annual mean concentrations. Extreme val-
ues instead occur mostly unforeseeable or even unex-
plainable in measurement, therefore it is not very
probable to believe, that they are included well dosed
in a model calculation. Therefore older regulations
looked on annual means, median, P 95 and perhaps P
98. In Europe instead, the critical load for hourly NO2
concentrations equals in measurement data the per-
centile P 99,8 (18 h).
We offer free definable percentile results (except for
Austal2000), because they are sensible to compare
planning options. For limit value comparison instead
we strictly recommend, to derive the extreme values
(or the probability to exceed extreme limits) from cal-
culated annual mean values, as it is mostly done in
Germany. Maybe the implemented German functions
must be modified according to your national statistics.
If there are any equations available, they can simply be
applied to the result maps by using the grid operations
of SoundPLAN's Graphics module.
Training
7
The purchase process often begins with using a demo
version to get an understanding of modeling tech-
niques before making a decision to purchase. For air
pollution propagation, there are many details to learn
about the different models besides learning how to
use the software. Especially if air pollution prognosis
is a new field of study, we feel the most efficient way
to begin is to attend a training session.
Although air pollution prognosis is a complex matter,
it doesn’t take long to learn how to recognize and
avoid problems throughout process. The model de-
velopers have done their work correctly, so you don’t
have to worry about the mathematics and the physics.
We focus your attention on weather and pollution ef-
fects, much of which you already know, and then
show you how these effects are parameterized as
model input for the different model approaches.
SoundPLAN air training shows the maximum reliabil-
ity expected in projects and the minimum data quality
required. It shows how the interaction between input
data and the calculation model determine model se-
lection. Above all, it shows how to maximize your time
and efforts for efficient, accurate air pollution progno-
sis.
Contents:
Wind in Nature
appearance and importance of
large scale and local wind sys-
tems
Modeling Wind
measurement and parameteri-
zation of wind characteristics
plumes and wind fields
Model Approaches
statistical approach
diagnostic approach
prognostic approach
Source Modeling
general approaches
modeling in SoundPLAN
HBEFA road emissions
Calculation Control
optimizing parameter settings
control by files & graphics
Result Display
wind fields
concentrations
post processing operations
The training projects and presentation slides are available on DVD. Three training days are required to fully cover
the topics for experienced SoundPLAN noise users. Four days should be planned for newcomers. Attendance from
first to last session is mandatory. If you want to discuss project data, send them to [email protected] be-
forehand with a description of the situation. We’ll look for ways to assist you with your particular projects, but
special preparations will increase the price. Prices will be calculated individually on request.
Modular architecture
SoundPLAN offers modular architecture in a double sense:
1. Working with SoundPLAN the work flow is split into several program modules to avoid an overload of buttons
within one interface and to assist an efficient organization of big projects with several model variants and cal-
culation tasks.
2. The calculation models are offered as separate license modules in the price list, because air pollution tasks can
be very different and require well selected model approaches. They spread from a "simple" Gauss model up to
complex prognostic models.
However, even if you can decide to buy as well simple as complex models, this is often misunderstood as a ques-
tion of comfort or background knowledge. Far from it! A wrong model selection can be more expensive than the
most expensive model!
The model selection depends strongly on the model area, the results requested by the directives and the available
input data. Therefore the modules can't simply replace each other.
To avoid damages we offer training sessions, designed to transport the needed background knowledge to con-
sultants who started with acoustics and want to enter the air pollution field.
As special offer to animate your training motivation we discount up to 20% of the module price from the train-
ing price, if you order a training within 3 months before or after purchasing the program.