- Interface - Mesoscale Dispersion Modeling

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AUSTAL2000 is a freeware offered by the German Federal Environment Agency 'UBA'. SoundPLAN relieves your efforts to prepare an AUSTAL2000 calculation and to display results by taking over all the writing and reading of circumstantial ASCII files. Using AUSTAL2000 in the SoundPLAN environment gives you the feeling to use only one program with all the comfort you know from other SoundPLAN applications.

Preparation

  • The SoundPLAN Meteorological Station Library helps to analyze meteorological data visually, adjust them to your task, to calculate stability classes and to export data to one of the supported AUSTAL2000 file formats.
  • The time histogram library helps to create and store cyclical time variant emission source parameters addressing each single hour of a year to support the AUSTAL2000 time series calculations. Alternatively ASCII-lists can be used to take non-cyclic time variant emissions into account. Whether emission time histograms are really used or replaced by an averaged constant emission flow depends on the file format selection for the Austal2000 meteo file.

Data input

  • SoundPLAN Geodatabase allows importing, digitizing and editing model data via several interfaces or just to use models prepared for SoundPLAN noise calculations. Background bitmaps can be used, e.g.  geo-referenced aerial photos.

Calculation

  • The SoundPLAN calculation kernel offers a user friendly interface to define the calculation settings and to control the runs. It allows running several calculations parallel, if you have several processors on your computer.

Presentation

  • The SoundPLAN Graphics module assists preparing outstanding presentation graphics. Even more, it allows also to modify data in a post processing by user defined formulas or to combine results of several calculation runs, whatever model was used, and to add additional site map information.

Limitation

SoundPLAN can't help you to jump over some restrictions of AUSTAL2000 freeware:

  • There is a limited list of available pollutants, each with only specific results which are strictly bound to the regulations of the German Standard TA Luft 02 (acc. to European EC Directive 2008/50/EC).
  • AUSTAL2000 is a quickly calculating model, but it uses only one processor per single calculation run. Therefore SoundPLAN can't distribute tasks to several kernels within one run.
  • The wind field model TALDIA which is offered with Austal2000 free of charge can calculate flow around buildings. However, in complex building structures this wind field is not suitable to calculate correct pollutant concentrations if the sources are close to the ground and close to the buildings (No street canyons!)
  • The SoundPLAN support is limited to the interface, because the AUSTAL2000 freeware kernel is not our product. However we are always open to share our AUSTAL2000 user experience.

Origin

Developed by Dr. Janicke (Dunum, Germany) as an exemplary freeware program for the German Federal Environment Agency (Umweltbundesamt UBA), AUSTAL2000 is also reference model of the German guideline on odor nuisance (GIRL, 2008).

Model Type and Field of Application

AUSTAL2000 is a three-dimensional Lagrangian particle dispersion model. It is set up and verified in conformance with the German guideline VDI 3945/3 as a mesoscale model to be used for assessment/licensing procedures or local and regional air quality studies. It is distributed together with TALDIA, a diagnostic wind field model for smoothly undulated terrain (up to 20% slope inclination). For emission sources close above roof tops the wind field should take buildings into account.

Regard that the combination AUSTAL2000/TALDIA is not qualified to substitute micro scale modeling for roads between buildings!

Time Resolution and meteorology

even for quick, coarse calculation of annual means usethreedimensional dispersion class statistics based on at least hourly measurement. Created in the SoundPLAN Meteorological Station Library they contain the frequency for each combination of 6 Klug/Manier stability classes, 9 wind speed classes and 36 wind direction sectors. Missing stability information can cause grave biases concerning the concentration results.

Alternatively hourly time series of meteorological measurement from 1 to 365 complete days regard time variant emissions and time variant effective source height parameters. Stability information must be Klug/Manier classes or Monin/Obukhov length.

If neither Klug/Manier classes nor Monin Obukhov length are available, SoundPLAN helps to use other measured parameters to get at least an acceptable approximation of Klug/Manier classes.

Spatial Resolution

Horizontal resolution: Typically between 15 meters and 200 meters. 2 meters are recommended, if buildings are explicitly regarded. Nested calculation grids are possible.

Vertical resolution: terrain following grid with 20-30 continuously spreading planes to reach a sensible domain height.

Emission Sources

AUSTAL2000 Emission sources are defined as point, line and rectangular area, optionally all can have a vertical expansion. SoundPLAN also offers freely shaped areas and a special road object, which are transformed to AUSTAL2000 sources.

For point, line and area sources an effective source height can be defined using several approaches to define thermal upstream, mechanical impulse, water content etc.

Pollutants

AUSTAL2000 supports only a fixed list of pollutant shortcuts, which directs the availability of results for specific pollutants.so2, no2, nox, bzl, tce, f, nh3, hg, odor, xxare allowed for neutral behaving gases. For odor additionally several extensions are allowed to specify a rating of annoyance. 'no' (Nitrogen monoxide) input results in NO2 output (based on transportation time dependent conversion according to German guideline VDI 3782/1).

Particles are named pm, as, pb, cd, ni, hg, tl, xx with an extension to define particle size classes with fixed deposition and sedimentation velocities. SoundPLAN allows renaming the pollutants in the presentations. This simple workaround helps to get results which are not offered for the desired substance - e.g. maximum value is calculated for no2, but not for nox. Masking nox as no2 you get also a maximum value for nox. If dust is defined by element short cuts (as, pb etc.), the results are stored with 3 decimal places more than pm.

A more flexible AUSTAL2000 concept was announced for 2012 but not yet released. We will adjust the SoundPLAN interface as soon as we get detailed information. Ask us for the current state. Austal2000 offers a list to expand the restrictions a littlebit. We don’t recommend to use it, because in our trials for several cases the modified settings were ignored and the calculation used default values without any hint or warning. Customers told about similar experience.

Topography

The wind field TALDIA used by AUSTAL2000 is approved for terrain inclinations up to 20 %. The program does not check the inclination itself, but checks for critical wind speed components. TALDIA considers terrain as an obstacle, but it doesnt calculate thermal winds such as local cold air flow or slope upstream. Therefore, in more complex terrain a running calculation is not a guarantee for a sensible result.

Buildings, Obstacles, Landuse

AUSTAL2000 used as a rough-screening model excluding buildings has acceptable calculation times, usually one to several hours. Used in fine spatial resolution including buildings, AUSTAL2000 calculations might take several days and will block a good part of your disk space when the calculation has finished.

For high sources most obstacles can be regarded by defining the average roughness length of an area. Regard: AUSTAL2000 allows only one roughness length for the whole model area!

  • Sources above 1,7 times the average obstacle height can be calculated without buildings.
  • Sources between 1,2 and 1,7 times the average obstacle height should regard buildings.
  • Sources below 1,2 times the average obstacle height require mostly another model, e.g. GRAL or MISKAM, depending on the scale and project area size.
  • NOTE: The TALDIA wind fields used by AUSTAL2000 are not suitable to model sensible dispersion of road exhaust in inner city situations!

Available Results

Mean values of concentration and deposition for the regarded time period (mostly annual), daily mean values and hourly mean values only for selected pollutants (strictly only supporting the limit values of European directive 2008/50/EC and German smell standard GIRL)

SoundPLAN displays grid maps for concentration, deposition, sampling error and smell hours. Additionally up to 20 monitor points can be set within the calculation area. For those monitor points only the original AUSTAL2000 protocols are available.

Original AUSTAL2000 command files, protocols and messages are available in English and German, depending on the installed language files.

Support

Our support is restricted to the interface and our own user experiences and interpretations. Usually we can't help you to rescue your project, if you work beyond the model limits of Austal2000.

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