Water effects on urban heat islands in summer using WRF-UCM with gridded urban canopy parameters - A case study of Wuhan

摘要

Urbanization has rapidly occurred in China along with a significant reduction in ecological resources, greatly exacerbating urban heat island effect. In cities with abundant inland lake resources, it is valuable to study the use of climate regulation effects of water bodies to improve the urban climate environment. In this study, we built a single-layer urban canopy model with higher accuracy by importing gridded urban canopy parameters and studied the impact of water bodies distributed in different areas of Wuhan on the urban thermal environment using a weather research and forecasting model (WRF). Water bodies located in the upwind suburbs had the greatest cooling impact on the microclimate of downtown areas during the day. Furthermore, they promote the evacuation of heat inside the urban canopy to the upper air by enhancing the lake breeze circulation. Late morning temperatures drop above the ground when the breeze circulation fully develops, while the temperature rise in the upper air increases. However, the cooling effect of these water bodies on the downtown area was affected by construction intensity in the suburbs. When the building density increased from 20% to 40%, the cooling effect did not change significantly. However, a further increase from 40% to 60% increased the pro-portion of intense heat island areas downtown, and the cooling effect of water bodies was also severely weak-ened. Moreover, with an increase in building density in the suburbs, the intense heat island areas north of the city gradually expanded to the city center.