长春市城市形态及风环境对地表温度的影响

Effects of urban morphology and wind conditions on land surface temperature in Changchun

随着城市化进程的加快,城市热岛效应越来越受到关注。然而,很少有研究分析城市形态和城市风环境对地表温度(LST)的影响。利用建筑和遥感等多源数据,基于GIS空间方法,结合迎风面指数(FAI)和地表温度,研究长春市城区迎风面指数时空差异,探索城市形态对城市地表温度影响。结果表明:①迎风面指数呈现从中心城区向外扩散的空间趋势,高密度以及高建筑对风的阻碍程度大。朝阳区北部迎风面指数最大,最大值达到15.1,各个区边缘区迎风面指数最小,最小值为0.01。②研究区昼夜地表温度温差大,范围分别是18.15℃～31.73℃、4.27℃～18.43℃。空间分布上与迎风面指数存在相同特征,城市中心城区温度高,以同心圆方式逐渐向外扩散。受城市建筑形态、人为热源等因素影响,与夜间相比,白天高温地区范围更大。③迎风面指数与地表温度在一定程度上相关,昼夜相关系数分别为0.371和0.355。建筑在垂直方向和水平方向上空间形态不同,对地表温度影响存在差异。结合城市风环境状况开展城市形态信息的定量研究,对于城市气候学家、城市规划师探寻城市潜在通风廊道、改善城市通风环境具有重要理论价值和现实意义。

The urban heat island effect has received an increasing attention recently with the acceleration of urbanization. However, so far few studies have focuses on the effects of urban morphology and wind conditions on land surface temperature(LST). This study utilizes a range of multi-source data including architecture and remote sensing and applies a GIS spatial method combined with urban building frontal area index(FAI) and LST. This research aims to evaluate spatiotemporal differences in the FAI of urban built-up areas as well as to explore the influence of urban form on surface temperature. Results initially reveal that building FAI conforms to a spatial trend comprising outward diffusion from the city center and shows that high density, higher elevation buildings hinder the wind strongly. Data show that FAI values for the north of Chaoyang District are the largest, reaching a maximum of 15.1, while those for edge areas for each district are the smallest, falling to a minimum of 0.01. Secondly, the results of this analysis reveal large differences in surface temperature between day and night within the study area, ranging between 18.15 ℃ and 31.73 ℃ and between 4.27 ℃ and 18.43 ℃,respectively. Spatial distribution values exhibit the same characteristics as those for the FAI;the urban central city is characterized by high temperature, which gradually spreads out in a concentric manner. The range of high temperature areas during the day is also larger than that at night as these values are influenced by other variables including urban architectural form and artificial heat sources. Thirdly, the data assembled here show that FAI is related to surface temperature to a certain extent;recorded correlations between day and night are 0.371 and0.355, respectively, both significant at the 0.01 level. It is also the case that building spatial shape is distinct in both vertical and horizontal directions and that the influence of surface temperature varies. Wind environmental data is an important component of quantitative research on building form and is necessary if urban climate scientists and planners are to explore and enhance potential ventilated corridors within cities.