基于局地气候分区体系的福州城市热环境研究

局地气候分区体系（LCZ）能够有效建立城市气候与空间形态间的定量关系,揭示城市内部热环境分异特征,是当前备受关注的城市热环境研究方法。本文以我国新晋“火炉城市”福州的主城区为研究区,使用2019年9月22日过空的Landsat-8影像,对基于LCZ的热环境空间分布特征与LCZ类间/类内差异进行分析,并就福州城市热环境的改善提出规划建议。研究表明:① 福州主城区以密集的中、低层连片建筑为主,并呈集聚式分布;② LCZ各类间存在明显的地表温度差异,大型低层建筑（LCZ 8）的温度最高,达41.56 ℃,密集低层建筑（LCZ 3）和工业厂房（LCZ 10）次之,分别为40.90 ℃和40.39 ℃,而茂密树木（LCZ A）和水体（LCZ G）的温度最低,均值为29.94 ℃;③ 根据福州城市发展的时空特征,将主城区分为二环区与三环区进行LCZ类内温度差异的比较分析,可以发现主城区内的主要LCZ建筑类别存在0.5~1.5 ℃的类内差异,造成这一差异的主要成因包括植被、水体等环境要素配置、建筑布局与邻近效应;④ 建筑层高与地表温度呈现显著的负相关关系（r=-0.858, p< 0.001）,并且由于高层建筑对太阳辐射的遮挡,其建筑阴影能够部分降低周边相对低矮建筑的表面温度和区域温度;⑤ 在今后的规划中,低矮连片的高密度居住区是改善城市热环境的重点区域,同时高层建筑虽有一定的降温效果,但对于城市风道的阻挡作用不可忽视,应留出足够的城市通风道。

A Study of Urban Thermal Environmental of Fuzhou based on "Local Climate Zones"

Local Climate Zones (LCZ) can effectively create the quantitative relationship between urban climate and urban spatial form and reveal the spatial variability of urban internal thermal environments. LCZ is a research method of urban thermal environment and has attracted a lot of attention at present. Therefore, this paper applies LCZ to study the spatial characteristics of urban thermal environment and its inter-/intra-zonal variability in Fuzhou City, a recently called “Stove city” in China. Furthermore, the planning strategy for the improvement of the urban thermal environment in Fuzhou is proposed. This study reveals that the main urban area in Fuzhou is dominated by compact mid- and low-rise buildings, which are distributed in a concentrated manner. In addition, the LCZ has obvious inter-zonal variability of land surface temperature (LST). Large low-rise building (LCZ 8) has the highest LST (41.56 ℃), followed by Compact low-rise (LCZ 3) and Heavy industry (LCZ 10) with LST of 40.90 ℃ and 40.39 ℃, respectively, while Dense trees (LCZ A) and Water (LCZ G) have the lowest LST with average LST of 29.94 ℃. At the same time, the intra-zonal LCZ variability also exists. We divides the main urban area into the second and third ring zones and analyzes the LST inter-zonal difference within each LCZ category. It can be found that the main LCZ building types have an inter-zonal difference between 0.5 ℃ and 1.5 ℃. The configuration of environmental factors, such as vegetation and water, buildings layout, and proximity effects, are the main causes of intra-zonal LCZ variability of LST. There is a significant negative correlation between building height and LST (r=-0.858, p<0.001). Moreover, due to the shielding of high-rise buildings from solar radiation, the building shade can partially cool the surface temperature of surrounding relatively low-rise buildings. However, the blocking effect of high-rise buildings on urban ventilation must be avoided. In the future, the contiguous, high-density, low-rise residential areas are the main areas to be controlled for their high temperature, and sufficient ventilation space should be reserved in urban planning.