Impact of urbanization factors considering artificial water dissipation on extreme precipitation: A numerical simulation of rainfall in Shanghai

Abstract

AbstractClimate change and rapid urbanization have jointly altered the climate characteristics of cities, including rainfall, humidity, and temperature, and have resulted in an increase of extreme precipitation. In this study, to identify the hydrothermal driving factors responsible for extreme precipitation in urban areas, sensitivity experiments were carried out on two extreme precipitation events in Shanghai, China, using the weather research and forecasting (WRF) model coupled with the artificial water dissipation urban canopy model (AWDUCM). The simulation results from the WRF model and observations from 35 weather stations across Shanghai were compared. The results showed that WRF could simulate the spatial distribution and precipitation intensity of extreme rainfall more accurately when integrated with the AWDUCM. With the AWDUCM incorporated, the root‐mean‐square errors of the two simulated precipitation events were 9.1 and 9.9 mm respectively (accounting for approximately 20% of the total rainfall). The near‐surface temperature and specific humidity in the AWDUCM simulation were approximately 0.5°C and 1 g·kg−1 higher than in the NON simulation (that did not invoke the AWDUCM) respectively. Urbanization factors increase the near‐surface temperature and specific humidity in urban and built‐up land, and the results of this study indicate that these are two of the driving forces affecting precipitation. Increased water vapor and urban heat island effects caused by urbanization are enhancing the intensity of extreme precipitation in Shanghai.