AustalTools: Enhancing Accessibility and Functionality of the AUSTAL Dispersion Model

Air pollution poses a substantial threat to public health, thus lawmakers, regulators, authorities and planners take measures to improve or at least maintain air quality. Atmospheric dispersion modelling represents a vital component of these measures. In Germany, the model AUSTAL serves as the reference implementation of such a model and is freely provided by Umweltbundesamt (UBA) under an open source licence. However, beyond the pure model, AUSTAL lacks tools for pre-processing, post-processing, and visualisation, in contrast to several other modelling systems provided by public authorities. The absence of free tools and the prohibitive high costs for most necessary input data have historically restricted its application.

Recent advances in the transformation of geoscientific information into open data have contributed to the reduction of these barriers. Specifically, substantial weather and national terrain datasets have become freely available. Nevertheless, in the absence of appropriate processing tools for the AUSTAL model, these data are still not usable.

For this purpose, AustalTools has been developed as a software solution with the aim of improving the usability and accessibility of the AUSTAL model. AustalTools has been implemented in Python with as few as possible dependencies for cross-platform compatibility. AustalTools facilitates the acquisition of weather and terrain input data by integrating sources such as the German Weather Service (DWD) and the Copernicus Climate Change Service (C3S), Copernicus Data Space, the US National Aeronautics and Space Administration (NASA) and the sixteen German state surveying offices.

AustalTools not only expedites data handling, but also supports the creation of time-dependent emission scenarios through simple weekly patterns or a versatile mini-language. It assists users in preparing AUSTAL configurations, including determining substitute anemometer positions (EAP) as defined by VDI 3783(16) and facilitating the import of building data from Geographic Information Systems (GIS). To assist with meeting quality assurance guidelines and checking output quality, AustalTools includes several simple plotting tools to visualise terrain steepness, concentration fields, wind fields and windroses.

The implementation of a variety of preprocessing schemes has the potential to offer supplementary insight into the methods themselves and their consequences for modelling results. Nevertheless, even the software's inherent functionality, which encompasses data acquisition, pre- and post-processing for AUSTAL, can be regarded as an advancement since it democratises access to professional-grade dispersion modelling, in particular for academic and amateur researchers and educators.