State Key Laboratory of Green Building in Western China, Xi'an University of Architecture and Technology, Xi'an, Shaanxi 710055, PR China; School of Architecture, Xi'an University of Architecture and Technology, Xi'an, Shaanxi 710055, PR China.
State Key Laboratory of Green Building in Western China, Xi'an University of Architecture and Technology, Xi'an, Shaanxi 710055, PR China; School of Architecture, Xi'an University of Architecture and Technology, Xi'an, Shaanxi 710055, PR China.
Sci Total Environ. 2020 Nov 15;743:140589. doi: 10.1016/j.scitotenv.2020.140589. Epub 2020 Jul 2.
Previous studies of the effects of regional climate conditions on urban heat islands (UHIs) focused mostly on surface UHIs, whereas few considered canopy layer UHIs. In the present study, a numerical modeling method is used to investigate the impacts of regional climate conditions on canopy layer UHIs at the district scale while controlling for the urban morphology. The urban morphology is classified according to the local climate zone (LCZ) system as LCZ1-LCZ6. Analysis of the spatial distribution of the urban heat island intensity (UHII) show that the nighttime and daytime UHII are most significantly correlated with the air temperature and wind speed, respectively. In five typical cities, LCZ1 has the most obvious urban heat island (UHI) effect, with an average annual UHII of 1-2.3 °C, which is about 1.5 times that for LCZ4. Reducing the building density has more significant influence on mitigating the UHI effect, where reducing the building height and building density reduce the heat island degree-hours (HIdh) by about 20% and 30%, respectively. The relationships between the UHII and meteorological conditions vary among different periods. For example, the correlation between UHII and average wind speed is more significant in the winter and at night. Our results help to understand the relationships between regional climate conditions and the canopy layer UHI at the district scale.
先前关于区域气候条件对城市热岛（UHI）影响的研究主要集中在地表 UHI 上，而很少考虑冠层 UHI。本研究采用数值模拟方法，在控制城市形态的情况下，研究区域气候条件对区域尺度冠层 UHI 的影响。城市形态根据局地气候区（LCZ）系统分为 LCZ1-LCZ6。对城市热岛强度（UHII）空间分布的分析表明，夜间和白天的 UHII 分别与气温和风速最显著相关。在五个典型城市中，LCZ1 具有最明显的城市热岛（UHI）效应，其平均年 UHII 为 1-2.3°C，约为 LCZ4 的 1.5 倍。降低建筑密度对缓解 UHI 效应的影响更为显著，降低建筑高度和建筑密度可使热岛度小时（HIdh）分别减少约 20%和 30%。UHII 与气象条件之间的关系在不同时期有所不同。例如，UHII 与平均风速之间的相关性在冬季和夜间更为显著。我们的研究结果有助于理解区域气候条件与区域尺度冠层 UHI 之间的关系。
