Lindberg Fredrik, Holmer Björn, Thorsson Sofia, Rayner David
Göteborg Urban Climate Group, Earth Science Centre, University of Gothenburg, Box 460, 405 30, Göteborg, Sweden,
Int J Biometeorol. 2014 Jul;58(5):613-27. doi: 10.1007/s00484-013-0638-y. Epub 2013 Feb 28.
Knowledge of how the mean radiant temperature (T mrt ) is affected by factors such as location, climate and urban setting contributes to the practice of climate sensitive planning. This paper examines how T mrt varies within an urban setting and how it is influenced by cloudiness. In addition, variations of T mrt in three high latitude cities are investigated in order to analyse the impact of geographical context and climate conditions. Results showed large spatial variations between sunlit and shaded areas during clear weather conditions, with the highest values of T mrt close to sunlit walls and the lowest values in the areas shaded by buildings and vegetation. As cloudiness increases, the spatial pattern is altered and the differences are reduced. The highest T mrt under cloudy conditions is instead found in open areas where the proportion of shortwave diffuse radiation from the sky vault is high. A regional comparison between three Swedish coastal cities showed that T mrt during summer is similar regardless of latitudinal location. On the other hand, large differences in T mrt during winter were found. Shadows, both from buildings and vegetation are the most effective measure to reduce extreme values of T mrt. However, extensive areas of shadow are usually not desired within outdoor urban environments at high latitude cities. One solution is to create diverse outdoor urban spaces in terms of shadow and also ventilation. This would provide individuals with access to a choice of thermal environments which they can use to assist their thermal regulation, based on personal needs and desires.
了解平均辐射温度（T mrt）如何受到位置、气候和城市环境等因素的影响，有助于开展气候敏感型规划实践。本文研究了城市环境中T mrt的变化情况以及它如何受到云量的影响。此外，还对三个高纬度城市的T mrt变化进行了调查，以分析地理环境和气候条件的影响。结果表明，在晴朗天气条件下，阳光照射区域和阴影区域之间存在很大的空间差异，T mrt的最高值出现在靠近阳光照射墙壁的地方，而最低值出现在建筑物和植被阴影覆盖的区域。随着云量增加，空间格局发生变化，差异减小。相反，在多云条件下，T mrt的最高值出现在来自天穹的短波漫射辐射比例较高的开阔区域。瑞典三个沿海城市的区域比较表明，夏季的T mrt无论纬度位置如何都相似。另一方面，发现冬季的T mrt存在很大差异。建筑物和植被的阴影是降低T mrt极值的最有效措施。然而，在高纬度城市的户外城市环境中，通常不希望有大面积的阴影。一种解决方案是在阴影和通风方面创造多样化的户外城市空间。这将为个人提供多种热环境选择，他们可以根据个人需求和愿望利用这些环境来辅助自身的热调节。
