Long-term trend of surface wind speed in the Guangdong-Hong Kong-Macau Greater Bay Area during 1980-2020: Spatiotemporal variation and urbanization effect

Understanding the surface wind speed variations is important for the climate and air quality assessment in the Guangdong -Hong Kong -Macau Greater Bay Area (GBA), known as the world class urban agglomeration in China. This study investigates the spatial and temporal variations of surface mean wind speed (MWS) in the GBA from 1980 to 2020, drawing upon ground observations and reanalysis data. After accounting for station relocations, the observed wind speed demonstrated a fluctuating declining trend of -0.036 m center dot s - 1 per decade over the examined period in line with reanalysis data. Wind speeds were found stronger during winter and daytime than summer and nighttime. The southern coastal regions exhibited higher MWS compared with northern mountainous areas. The Empirical Orthogonal Function (EOF) revealed the dominant mode of MWS changes was characterized by a cyclical pattern lasting over 20 years, probably influenced by atmospheric circulation. The urbanization reduced the observed wind speeds by 4.71% - 10.11% over the past decade (2011-2020) in urban areas of the GBA based on urbanminus -rural (UMR), observation -minus -reanalysis (OMR), and urban impact factor (UIF) methods. The long-term spatio-temporal analyses of MWS could benefit the climate and air quality studies and provide data support for regional and micro -scale modeling in the GBA.