居住区典型地物热环境的日变化及其相互影响分析

Diurnal Variation and Mutual Influence of Typical Ground Objects’ Thermal Environment in Residential Areas

居住区热环境状况是影响局地微气候变化的重要因素,研究居住区地物的热环境特征,对于了解和改善微气候具有重要意义。为了更好地揭示居住区热环境特征,本研究使用热红外成像仪对北京市某校园居住区进行观测,获取了夏季不同天气状况下(晴天、阴天、多云)的24 h热红外影像数据。依据各天气数据和地物属性,系统分析了各地物日变化规律,并通过垂线法判定邻近地物的温度边界范围,进而揭示出地物间温度交互特征。结果如下:①太阳辐射是影响地物白天温度变化的主要因素,与地物温度呈正相关性;在多云天气下,地物的最高温度滞后至16:00出现,且地物温度曲线呈现连续的"锯齿状"升降趋势,云层的大量运动是导致多云天气下的地物温度波动变化的关键因素;沥青道路在夜间的温度均高于其他地物,并且夜间持续放热,提生周围环境温度;阴影能够有效减少地物吸收的太阳辐射量,降低地物表面温度;植被的冠层厚度与地物温度呈负相关性,因此增加居住区内绿植的冠层厚度,增大区域阴影面积有助于改善局地微气候;②树木和裸土在06:00和14:00的温度交互作用强烈,表明在地物交界处,全天持续发生显著的热量交换;而夜间至凌晨,草坪与人行道持续进行热量交换,帮助降低路面温度,缓解周围高温状况。

Along with acceleration urbanization, the urban heat island effect is increasingly intensifying due to urban construction. In particular, the thermal environment of residential areas has a profound influence on the local micro-climate. Therefore, studying the thermal environment characteristics of residential areas is of great significance for understanding and improving the local micro-climate. To reveal the thermal environment characteristics of residential areas, this study focused on a residential area in a campus of Beijing by using thermal infrared imagery, and obtained 24 hours thermal infrared data under different weather conditions(clear sky, cloudy, overcast sky) in summer, then selected typical urban ground objects(buildings, iron sheds, asphalt roads, bare soil, trees and shrubs, etc.), and systematically analyzed the diurnal variations of objects in different regions. Finally, the interactive features of the ground objects’ temperature were revealed by using a tangent method to determine the boundary ranges of the ground objects. The main results are as follows:(1) The surface temperature curve of artificial ground objects(such as buildings and iron sheds) shows continuously violent ups and downs because of the dramatic changes of solar radiation. It indicates that solar radiation is the main factor affecting the temperature change of ground objects during the daytime, with positive correlation with the temperature of ground objects. In the cloudy weather, the maximum temperature of ground objects occurs after 16:00. Cloud movement increases the temperature fluctuation of ground objects, especially in the cloudy weather. Asphalt roads have higher temperatures at night than other ground objects, and continue to radiate heat at night resulting in ambient temperature increases. Shadow could effectively reduce the amount of solar radiation absorbed by ground objects and reduce the surface temperature. Vegetation canopy thickness is negatively correlated with the temperature of ground objects. Therefore, in residential areas, increasing the vegetation canopy thickness and expanding shadow areas will improve the local micro-climate.(2) The strong temperature interaction between trees and bare soil at 06:00 and 14:00 indicates that significant heat exchange occurs throughout the day at the junction of ground objects. At 06:00, the temperature at the junction of lawn and sidewalk has a significant interaction, indicating that there is heat exchange between the lawn and the pavement from night to early morning. It helps relieve the high temperature of the road and the surrounding environment.