High-resolution dataset of urban canopy parameters for Beijing and its application to the integrated WRF/Urban modelling system

The Weather Research and Forecasting (WRF) model with urban canopy model has been widely used to study atmospheric boundary layer processes and urbanization-related environmental issues. One of the most daunting challenges faced by the integrated WRF/urban modelling system is constraining the uncertainties in urban canopy parameters (UCPs) that represent the urban morphological characteristics. In this paper, we develop a dataset of three-dimensional (3-D) UCPs for Beijing by using vector-format building information in a Geographic Information System (GIS) environment and apply it to the integrated WRF/urban modelling system to investigate the effects of UCPs on the simulated meteorological variables against observations in clear-sky days. Moreover, the role of spatially-varying UCPs involved in the Building Effect Parameterization (BEP) in capturing the heterogeneous characteristics of 2-m surface air temperature and 10-m wind field in the urban areas are evaluated. In general, high-resolution dataset of UCPs improves the model skill in simulating the diurnal variations and spatial distributions of 2-m surface air temperature and 10-m wind speed in the urban canopy, especially for the BEP. WRF/BEP with gridded UCPs dataset shows a better performance in densely built-up areas, where the morphological and physical characteristics of urban surface are complex. It also performs better in capturing the characteristics of urban heat islands (UHIs) and weak wind zones (WWZs) in urban areas. Results show that introducing the 3-D UCPs dataset into the integrated WRF/urban modelling system is a simple and yet efficient way to enhance the modelling capabilities in urban areas and assist urban planners to deal with urban environmental issues. (C) 2018 Elsevier Ltd. All rights reserved.