Numerical Simulation of the Effect of Large Scale Wind on Urban Heat Island

The Weather Research and Forecasting (WRF) model coupled with a singlelayer Urban Canopy Model (UCM) is used to simulate the Urban Heat Island (UHI) features in Shanghai and Nanjing, two different cities in China. Results show that the horizontal distribution of UHI is determined by largescale surface wind, which causes high air temperature of downstream rural area. Cross sections of the difference of air temperature between the urban and rural surfaces are analyzed, the model suggests that more heat is transported from the land to the air over urban area, which leads to the continuous transportation of heat to the downstream rural surface under the control of the steady largescale wind. It is concluded that the effect of largescale surface wind on UHI can increase the downstream rural air temperature, which shouldn’t be ignored.