Correspondence between urbanization and surface wind in the Guangdong-Hong Kong-Macao Greater Bay Area: Observations and idealized large-eddy simulation

Abstract

Guangdong-Hong Kong-Macao Greater Bay Area (GBA) megalopolis has been experiencing a rapid progress of the urbanization during recent decades, leading to an obvious change of surface wind speed (SWS). In this study, the variations of SWS and nighttime light imageries (NLI) and their correspondences over GBA are firstly investigated. The whole GBA presents a significant declining trend of SWS at a rate of 0.24 m s−1 decade−1 in the past decade, accompanied by an obvious increasing trend of NLI. The SWS is significantly negatively related to NLI (R = −0.81; p < 0.001) averaged over the GBA. However, there exist scattered positive centers, especially over the eastern part of a high level of urbanization. Since the correspondences between SWS and building configurations might be varied in the different stages of urbanization, the urbanization process is conceptualized into the Phase I (i.e., density increase) and II (i.e., height increase) for the large-eddy simulations. In particular, SWS presents a moderate oscillation in Phase I, but surges in Phase II. Accordingly, the SWS amplification under the urbanization development is mainly due to the channelized flow and deflected backflow, as well as their interactions.