| 摘要: |
| 在全球气候变化背景下，本研究以西安市碑林区为例，监测中国寒冷地区城市冬季和过渡季城市空间热环境差异。本研究采用移动测量方法，从人行和骑行视角获取数据，探讨天空视角因子（SVF）、平均建筑高度、建筑密度和蓝绿空间对西安城市热环境的影响。结果显示：白天，除靠近水体的测点外，气温与SVF有较好相关性；夜晚，高绿地覆盖率能够降低空气温度，而较高的建筑密度则促进空气温度升高。蓝绿空间的降温效果在一天中及不同季节存在差异，夜晚降温效果远大于白天。回归分析发现，冬季水体的降温范围约为1300-1500米。研究结论聚焦各指标与城市空间热环境变化之间的关系，为推动不同热工分区的城市的规划与城市更新提供了建议。 |
| 关键词: 城市热环境 移动测量 城市空间形态 蓝绿空间 天空视角因子 |
| DOI： |
| 分类号:TU111.2 |
| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目）高密度城市建筑气候参数模型建构与应用（项目批准号：52278087） |
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| A Study on the Thermal Environment Differences in Urban Spaces in Cold Regions |
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Xia Bo, Kuai Hongyu, Liu Xiaoqian, Zhao Jingyuan
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| Abstract: |
| Under the dual pressures of accelerating urbanization and global climate change, the urban thermal environment has become a critical factor influencing outdoor thermal comfort, environmental quality, and urban sustainability. Although extensive research has addressed summer heat stress and large-scale urban heat island effects, relatively limited attention has been given to winter and transition-season thermal environments, particularly at the local scale where pedestrians directly experience microclimatic conditions. In cold-region cities, seasonal and diurnal thermal characteristics differ fundamentally from those observed during hot periods, underscoring the need for season-specific investigations to support climate-responsive urban planning and renewal. This study examines spatial differences in the urban thermal environment during winter and transition seasons in a cold-region city, using Beilin District in Xi’an, China, as a representative case. Xi’an is located in Cold Zone B of China’s thermal zoning system and is characterized by a complex urban morphology shaped by historical urban fabric, dense built-up areas, and blue-green spaces. To capture fine-scale thermal variations from a human-centered perspective, a mobile measurement approach was adopted, enabling the assessment of microclimatic conditions along pedestrian and cyclist routes rather than relying solely on fixed-point observations. Field measurements were conducted during a representative transition-season day (November 2023) and a winter day (January 2024). Two daily periods were selected to represent contrasting thermal conditions: a daytime period with relatively strong solar radiation (15:00-16:00) and a nighttime period without solar influence (19:00-20:00). Environmental parameters, including air temperature, relative humidity, globe temperature, and wind speed, were measured at a height of 1.5 m along a predefined route covering diverse urban spatial forms, such as historic inner-city streets, multi-story and high-rise street canyons, urban parks, and waterfront areas. Sky View Factor (SVF) was derived from fish-eye photographs taken at each measurement point. In total, 43 measurement points were established at approximately 100 m intervals, with denser sampling near water bodies to capture localized cooling effects. To explore the influence of urban spatial characteristics on the thermal environment, four key indicators were analyzed: SVF, average building height, building density, and green coverage ratio, with particular emphasis on blue-green spaces. Spatial interpolation using the Kriging method was applied to visualize temperature variations along the measurement route, while correlation and regression analyses were employed to quantify relationships between air temperature and urban form indicators. The results reveal pronounced seasonal and diurnal differences in urban thermal behavior. During daytime, air temperature shows a moderate positive correlation with SVF at locations where urban geometry is the dominant controlling factor, indicating that more open spaces tend to experience higher air temperatures under winter and transition-season solar radiation. In contrast, this relationship becomes insignificant in areas influenced by adjacent water bodies, where cooling effects associated with blue spaces override the influence of urban geometry. Areas characterized by greater building height and deeper street canyons generally exhibit lower daytime air temperatures due to shading effects and reduced solar exposure. At night, the dominant controlling mechanisms shift. Green coverage and building density emerge as key factors shaping nocturnal air temperature patterns. Areas with higher green coverage consistently exhibit lower nighttime air temperatures, reflecting enhanced long-wave radiative cooling and reduced heat storage. Conversely, higher building density is associated with elevated nighttime air temperatures, suggesting that dense built environments retain and release accumulated heat, reinforcing nighttime warming. The influence of average building height on nighttime air temperature is comparatively weak, indicating that shading effects play a limited role once solar radiation is absent. Blue-green spaces demonstrate a clear cooling effect across both seasons, with a substantially stronger influence at night than during the day. Regression analysis of nighttime air temperature against distance from water bodies indicates that, in winter, the cooling effect of large urban water bodies extends approximately 1300-1500 m from the shoreline. This distance represents a characteristic spatial scale derived from polynomial regression rather than a strict physical boundary. In the transition season, although nighttime cooling near water bodies is evident, the spatial influence range is less clearly defined, suggesting seasonal differences in the thermal behavior of urban water bodies. Overall, the findings indicate that the urban thermal environment in cold-region cities is governed by a complex interplay among urban morphology, blue-green spaces, seasonal background climate, and diurnal cycles. The results further demonstrate that thermal mitigation strategies effective in summer cannot be directly transferred to winter or transition seasons without adjustment. From a planning perspective, excessive building density should be carefully controlled to mitigate nighttime heat accumulation, while the integration and preservation of blue-green spaces can provide significant thermal benefits even in cold seasons. In newly developed areas, compact yet climate-sensitive urban forms combined with adequate blue-green infrastructure are recommended, while urban renewal in existing districts should prioritize increasing green coverage and optimizing spatial configurations to improve thermal performance across seasons. |
| Key words: Urban thermal environment Mobile measurement Urban spatial form Blue-green spaces Sky View Factor |
