Urbanization Impact on Regional Wind Stilling: A Modeling Study in the Beijing-Tianjin-Hebei Region of China

Prominent slowdown in near-surface wind speed (NSWS) has been observed in the Beijing-Tianjin-Hebei (BTH) region of China, which has important implications for regional haze mitigation and wind energy production. Other than large-scale climatic variation, this decline is suspected of being linked to the impact of urbanization. Based on nested high-resolution simulations using the Weather Research and Forecasting model, we assessed quantitatively the respective roles of urban development and anthropogenic heat (AH) in regional NSWS change over the BTH region from a climatological perspective. The contribution of urbanization to station average annual NSWS over 1980-2018 was estimated to be approximately -0.37 m s(-1), with the largest decline exceeding -1.0 m s(-1) in some highly urbanized areas. The effect of urban development on NSWS was found partly offset by the AH effect. Urbanization-induced NSWS decrease was most remarkable in spring and early in the night. Urbanization impacts on NSWS were more remarkable when regional prevailing winds were northeasterly and northwesterly. Further analysis showed that the simulated urbanization-induced decreases in NSWS were highly correlated with the background regional NSWS levels. Our simulation results indicated that urbanization was an important but not a dominant cause of the observed regional wind stilling, even in such a rapidly urbanizing region, although it had remarkable influence on local NSWS in highly urbanized areas.