Numerical Analysis on the Contribution of Urbanization to Wind Stilling: An Example over the Greater Beijing Metropolitan Area

A decline of surface wind speed (wind stilling) has been observed in many regions of the world. The greater Beijing metropolitan area in China is taken as an example for analyzing the urbanization impact on wind stilling. This study set up five scenarios with different urbanization ratios and the same atmospheric forces and then simulated wind speed under each scenario using the next-generation Weather Research and Forecasting model. The results suggest that the correspondence between the regional average wind speed ratio of decrease Δ u and the ratio of urbanized area δ urban (%) fits the relation in summer and in winter. During the period 1961–2008, the ratio of urbanized area over the greater Beijing metropolitan area increased from 1.3% to 11.9%, which is speculated as the cause of a 0.4 m s −1 decline in regional average wind speed and the contributor to about 35% wind stilling.