Statistical characteristics of the morphological parameters of Chinese cities and the application in WRF model

With ever-increasing urban populations, cities face a serious of climatic and environmental issues such as urban heat islands (UHIs), air pollution and extreme weather. Urban morphological parameters can improve the performance of WRF model in urban areas. A 3-D urban canopy parameters (UCPs) are calculated for the 62 major cities in China.Chinese cities could be divided into two types (single_peak and double_peak) based on the distribution of building height, and the two peaks are located at level 2 (about 5m) and level 6 (about 20m). The mean number of buildings in single_peak city is much larger than that of double_peak.The building height of double_peak cities is larger than that of single_peak cities, but the building plan area fraction, building surface area to plan area ratio and frontal area index are opposite. The WRF default setting underestimates the street width but overestimates the building width of Chinese cities. The UCPs improve the simulation of nocturnal 2-m surface air temperature and 10-m wind speed in the testing cases.