Contributions of urban green and blue spaces on local-scale climate in the core area of Beijing, China

Construction of urban green and blue spaces (UGBS) has long been proved as an effective mitigation to urban heat island effect. Yet we spotted a rarity of studies evaluating UGBS's climatic effect difference in different land-uses, and a rarity of empirical evidence on better UGBS allocation for better cooling. In this study, we conducted field measurements of nighttime air temperature (Ta) and relative humidity (Rh) along an enclosed transect at the core area of Beijing, China, and evaluated the contributions of UGBS on local-scale climate. Land-cover types and land-use classification scheme Local Climate Zone (LCZ) were used to analyze measured Ta and Rh. Urban vegetation coverage is further intersected with LCZs to evaluate vegetation's cooling and humidifying effects in different land-uses. Results show that better correlations were generally detected with larger buffer zones when more land-cover and land-use conditions were included. UGBS exhibit significant cooling and humidifying effects, and better regression models were built when green and blue spaces were taken as a whole rather than independently. Coverage of LCZ 1 (compact high-rise), LCZ 2 (compact midrise) and LCZ G (water coverage) were found to more significantly contribute to local-scale climate. Increasing vegetation coverage in LCZ 2 and LCZ 3 is expected to facilitate better cooling and humidifying effect. Results of this study may provide insights for practitioners to allocate UGBS for better urban cooling.