Introduction

LASAT (Lagrange simulation of aerosol transport) is a model to simulate the dispersion of atmospheric air pollutant. It was developed by Ingenieurbüro Janicke and it is used by our office of engineering in the current version (q.v. www.janicke.de).

The model is a  Lagrangian dispersion model und it is conform to the directive VDI 3945, Part 3 (particle model).

Application

LASAT is used by our office for expert opinions e. g. roads, industry, odour and so on in two fields:

  a.) Typical Cases (single use)

  b.) specific cases in combination with other models

To a.) examples are listed in the following:

-    dispersion calculation with time series in consideration of chronological correlation between emissions and meteorology

-    consideration of elevation and land use, e.g. for variable horizontal deposition velocities of dispersion calculations

Fig. 1 shows the distribution of concentrations along roads within an explicit consideration of terrain.

Abb. 1: Air pullutant concentrations computed with LASAT, terrain effect: pollutant plume reaches valleys without emission sources

Fig. 2  shows an example for areal distribution of total nitrogen deposition in the close-up range of a road.

Fig. 2: With LASAT calculated total nitrogen deposition in the close-up range of a road

To b.) Examples for specific cases in combination with other models

-    Consideration of nocturnal drainage flow in the dispersion model (coupling of LASAT/KALM)

-    Embed external prognostical library of wind fields [e.g. in case of strong terrain slope or circulation around buildings  (LASAT/METRAS or LASAT/MISKAM Combinations)].

In addition of using wind fields with an internal diagnostical model (LPRWND) in LASAT it is also possible to integrate wind fields that are calculated externally. In Fig. 3 there is shown an example of computate a dispersion calculation using LASAT in consideration of affected nocturnal drainage flow.

Fig. 3: Total nitrogen deposition calculated with LASAT with embeded wind fields of nocturnal drainage flows

Additional a combination of wind fields and turbulence flows of the prognostical, micro scaled flow pattern calculated with MISKAM could take place.  Fig. 4 illustrates an example.

Abb. 4: Air pollutant concentration under consideration of a 3-dimensional dispersion model MISKAM (Lohmeyer, 2010)

Due to area with strong terrain slope the wind fields for the dispersion models LASAT can be calculated with the prognostical, meso scaled flow pattern model METRAS-PC.

The calcualation with prognostical models in LASAT (or AUSTAL) in combination of wind fields and turbulence flows externally produces more significant results e. g. immissions than the standard diagnostic flow field modeling in LASAT.

Fig. 5: Wind field at ground level calculated with METRAS-PC for an incoming flow of 270 degrees, an geostrophic wind of 3 m/s and a stable atmospheric layer (Lohmeyer, 2004)

Summary

LASAT is regarded as an accepted model for dispersion calculating of air pollutant. It could be used for various technical requirements, for typical individual applications and in combination with other models of a micro or meso scaled investigation area. So for each level of professional requirement it is achieved a result of high quality.

References

Lohmeyer (2010): Modellierung der PM10-Konzentrationen inkl. Inhaltsstoffe für die „Schlossparkepisode“ im Bereich Stuttgart-Neckartor. Ingenieurbüro Lohmeyer GmbH & Co. KG, Radebeul. Projekt 70566-09-10, November 2010. Gutachten im Auftrag von: Landesanstalt für Umwelt, Messungen und Naturschutz Baden-Württemberg, Karlsruhe.

Lohmeyer (2004): Fachinformationssystem METEOKART GIS, Modul Kaltluft für Teil-gebiet „Osterzgebirge“. Ingenieurbüro Lohmeyer GmbH & Co. KG, Radebeul. Projekt 70062-03-10. November 2004. Fachbericht im Auftrag von: Sächsisches Landesamt für Umwelt und Geologie, Dresden.

Janicke (2011): Dispersion Model LASAT Version 3.2 Referenz Book. Janicke Consulting, Dunum, August 2011.

Richtlinie VDI 3945, Blatt 3 (2000): Umweltmeteorologie - Atmosphärische Ausbreitungsmo­delle - Partikelmodell. September 2000.