Ventilation of a Mid-Size City under Stable Boundary Layer Conditions: A Simulation Using the LES Model PALM

City centers have to cope with an increasing amount of air pollution. The supply of fresh air is crucial yet difficult to ensure, especially under stable conditions of the atmospheric boundary layer. This case study used the PArallelized Large eddy simulation (LES) Model PALM to investigate the wind...

Authors: Biehl, Jonathan Lukas
Paas, Bastian
Klemm, Otto
Division/Institute:FB 14: Geowissenschaften
Document types:Article
Media types:Text
Publication date:2021
Date of publication on miami:27.09.2022
Modification date:27.09.2022
Edition statement:[Electronic ed.]
Source:Atmosphere 12 (2021) 3, 401, 1-14
Subjects:stable boundary layer; large eddy simulation; urban climatology; fresh air corridor; air ventilation assessment; city planning
DDC Subject:550: Geowissenschaften, Geologie
License:CC BY 4.0
Language:English
Funding:Finanziert durch den Open-Access-Publikationsfonds der Westfälischen Wilhelms-Universität Münster (WWU Münster).
Format:PDF document
URN:urn:nbn:de:hbz:6-62069546599
Other Identifiers:DOI: 10.17879/72089470196
Permalink:https://nbn-resolving.de/urn:nbn:de:hbz:6-62069546599
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  • Digital documents:10.3390_atmos12030401.pdf

    City centers have to cope with an increasing amount of air pollution. The supply of fresh air is crucial yet difficult to ensure, especially under stable conditions of the atmospheric boundary layer. This case study used the PArallelized Large eddy simulation (LES) Model PALM to investigate the wind field over an urban lake that had once been built as a designated fresh air corridor for the city center of Münster, northwest, Germany. The model initialization was performed using the main wind direction and stable boundary layer conditions as input. The initial wind and temperature profiles included a weak nocturnal low-level jet. By emitting a passive scalar at one point on top of a bridge, the dispersion of fresh air could be traced over the lake’s surface, within street canyons leading to the city center and within the urban boundary layer above. The concept of city ventilation was confirmed in principle, but the air took a direct route from the shore of the lake to the city center above a former river bed and its adjoining streets rather than through the street canyons. According to the dispersion of the passive scalar, half of the city center was supplied with fresh air originating from the lake. PALM proved to be a useful tool to study fresh air corridors under stable boundary layer conditions.