A rapid fine-scale approach to modelling urban bioclimatic conditions

Yannick Back; Peter Marcus Bach; Alrun Jasper-Tönnies; Wolfgang Rauch; Manfred Kleidorfer

doi:10.1016/j.scitotenv.2020.143732

A rapid fine-scale approach to modelling urban bioclimatic conditions

Sci Total Environ. 2021 Feb 20:756:143732. doi: 10.1016/j.scitotenv.2020.143732. Epub 2020 Nov 25.

Authors

Yannick Back¹, Peter Marcus Bach², Alrun Jasper-Tönnies³, Wolfgang Rauch⁴, Manfred Kleidorfer⁴

Affiliations

¹ Unit of Environmental Engineering, University of Innsbruck, Technikerstrasse 13, 6020 Innsbruck, Austria. Electronic address: Yannick.Back@uibk.ac.at.
² Swiss Federal Institute of Aquatic Science & Technology (EAWAG), Überlandstrasse 133, 8600 Dübendorf, ZH, Switzerland; Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland.
³ Hydro & Meteo GmbH, Breite Strasse 6-8, 23552 Lübeck, Germany.
⁴ Unit of Environmental Engineering, University of Innsbruck, Technikerstrasse 13, 6020 Innsbruck, Austria.

PMID: 33279193
DOI: 10.1016/j.scitotenv.2020.143732

Abstract

Surface characteristics play a vital role in simulations for urban bioclimatic conditions. Changing relationships and distribution patterns of sealed and vegetated surfaces as well as building geometry across different scales in urban environments influence surface temperatures. Cities comprise different urban forms, which, depending on their surface characteristics, enhance the heating process, increasing the emergence of urban heat islands (UHIs). Detecting priority areas to introduce multi-beneficial climate change adaptation measures is set to be a key task for the cities long-term strategies to improve climatic conditions across different urban structures and scales. We introduce a simple and fast spatial modelling approach to carry out fine-scale simulations for land surface temperature (LST), mean radiant temperature (MRT) and Universal Thermal Climate Index (UTCI) in a 2D environment. Capabilities of our modelling approach are demonstrated in evaluating urban thermal comfort in the alpine city of Innsbruck, the capital of Tyrol in western Austria. Results show a major contrast between sealed and vegetated surfaces reflected in the distributional patterns and values of LST, MRT and UTCI, correlating with the appearance and frequency of specific surface classes. We found the Sky View Factor to have a substantial impact on calculations for bioclimatic conditions and see high-albedo surfaces decrease LST but increase the apparent temperature (MRT and UTCI values) effecting human thermal comfort. Furthermore, MRT and UTCI are more sensitive to changes in emissivity values, whereas LST is more sensitive to changes in Bowen Ratio values. Application of our modelling approach can be used to identify priority areas and maximise multi-functionality of climate change adaptation measures, to support urban planning processes for heat mitigation and the implementation of policy suggestions to achieve sustainable development goals and other political objectives.

Keywords: Geographic Information System (GIS); Heat stress; Priority areas; Spatial modelling; Urban amenity; Urban form.