Identification of ventilation corridors using backward trajectory simulations in Beijing

Regional ventilation corridors (RVCs) have the ability to alleviate urban heat islands (UHIs) and air pollution caused by the continuous development and expansion of cities. Traditional methods for researching RVCs are typically based on Geographic Information Systems (GIS) or Computational Fluid Dynamics (CFD). In this study, a new method based on backward trajectory simulation, which has rarely been employed in RVC identification, is proposed to overcome the limitations of GIS- and CFD-based methods. Taking Beijing as the research area, this study evaluates regional ventilation potential based on wind statistics, surface roughness, and wind field simulated by the Weather Research and Forecasting (WRF) model. Moreover, the backward mode of FLEXPARTWRF is used to identify RVCs flowing through the city. The spatiotemporal differences between the RVC boundary layer ventilation (BLV) and urban canopy layer ventilation (UCLV) on synoptic and seasonal scales under meso-scale atmospheric circulation in different seasons are effectively identified. Some RVC characteristics that have not been found in previous studies are revealed: In winter, RVCs affecting the BLV of Beijing include mainly a northeast RVC and a west RVC, and the northeast RVC also affects UCLV. In summer, the southwest corridor contributes the most to ventilation.

Automated summary

This study proposes a new method for identifying RVCs using backward trajectory simulation, aiming to overcome the limitations of GIS and CFD-based methods. The research reveals spatial and temporal differences of RVCs, uncovering some characteristics that have not been found in previous studies.