Large-eddy simulation of urban air quality: A 'Ruisdael' case study of the city of Rotterdam

Abstract

The dispersion of air pollutants is strongly controlled by the stability of the atmosphere. For example, the diurnal variation of the net radiation received at the ground surface causes the vertical turbulent transport to be much stronger during daytime as compared to the night. We use the Dutch Atmospheric Large-Eddy Simulation (DALES) model to study the dispersion of air pollutants that are emitted at local spots in urban areas. To take into account the presence of buildings the immersed boundary method has been implemented in DALES. We use data from the 'Algemene Hoogtekaart Nederland' which provides the building heights at a very high spatial resolution (< 1 m). The large-scale meteorological forcings such as, for example, the horizontal pressure gradients, are taken from the KNMI mesoscale weather forecast model HARMONIE. As part of the national Ruisdael research program an intensive measurement campaign will take place in the city of Rotterdam during the summer of 2022. One of its aims is to provide data for model validation. Some preliminary simulation results will be presented.