Abstract

A multi-model simulation system for street level circulation and pollutant tracking (S-TRACK) has been developed by integrating the Weather Research and Forecasting (WRF), the Computational Fluid Dynamics (CFD) and the Flexible Particle (FLEXPART) models. The winter wind environmental characteristics and the potential impact of a traffic source on nearby sites (about 300 to 400 m) in Jinshui district of Zhengzhou, China are analyzed with the system. It is found that the existence of buildings complicates the structure of the wind fields. The wind speed inside the building block is smaller than the background wind speed due to the dragging effect of dense buildings. Ventilation is better when the dominant airflow is in the same direction as the building layout. Influenced by the building layout, local circulations show that the windward side of the building is mostly the divergence zone and the leeward side is mostly the convergence zone, which is more obvious for high buildings and influencing air pollution transport at the street-level. Using the traffic source (line source) on a road within a city block, the system was applied to investigate the potential impact of a line source on specific sites under the influence of the streel-level circulations. The potential contribution ratio was estimated by the method of residence time analysis and to a particular site found to vary with the height of the site with a peak not at the ground but on a certain height. The results of the study are helpful to understand the characteristics of wind environment and effect of traffic emissions in the area, which is important to improve urban living environment and control air pollution.

Highlights

  • In recent decades, with the continuous development of urban construction in China, urban environmental problems have become increasingly serious and attracted widespread attentions

  • The performance of Weather Research and Forecasting (WRF) model to simulate meteorological elements is an important basis for Computational Fluid Dynamics (CFD) and FLEXPART simulations

  • The hourly meteorological data for January 2019 obtained from the innermost nested simulation of the WRF model is selected to compare with observation data to verify the WRF model

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Summary

10 Abstract

A multi-model simulation system for street level circulation and pollutant tracking (S-TRACK) has been developed by integrating the Weather Research and Forecasting (WRF), the Computational Fluid Dynamics (CFD) and the Flexible Particle (FLEXPART) models. The winter wind environmental characteristics and the potential impact of a traffic source on nearby sites (about 300 to 400 m) in Jinshui district of. Using the traffic source (line source) on a road within a city block, the system was applied to investigate the potential impact of a line source on specific sites under the influence of the streel-level circulations. The results of the study are helpful to understand the characteristics of wind environment and effect of traffic emissions in the area, which is important to improve urban living environment and control air pollution

Introduction
Data and Methods
WRF model configuration
CFD configuration
Physical model and boundary conditions
Model evaluation
The characteristics of the street-level wind fields
The average wind field characteristics
The wind field characteristics under different background wind directions
Potential impact of a traffic source
Potential impact of traffic source at different sites in winter
Potential impact of traffic source under different background wind directions
Conclusions
Full Text
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