Cities are experiencing more and more frequent extreme heat events in hot summers in the context of rising global temperatures. A precise understanding of the spatial distribution of the human outdoor heat exposure across neighborhoods in cities is of great importance for urban heat management. Different from remote sensing based the land surface temperature, this study calculated the mean radiant temperature, which is more objective to indicate human heat stress, to study the spatial distribution of human outdoor heat exposure in Philadelphia, Pennsylvania. The SOLWEIG (SOlar and LongWave Environmental Irradiance Geometry) model was applied to estimate the mean radiant temperature based on the high-resolution urban 3D model and meteorological data. This study further examined the spatial distributions of heat exposure levels across neighborhoods of different groups in Philadelphia. Results show that there is no significant disparity in terms of outdoor heat exposure levels for different racial/ethnic groups in Philadelphia. Generally, the elderly, who usually are more vulnerable to extreme heat, tend to live in neighborhoods with less outdoor heat exposure in summer (p<0.001). The higher-income people tend to live in thermally more comfortable neighborhoods (p<0.001). The study provides a precise understanding of the heat distribution across neighborhoods, which would further help to develop strategies to allocate resources to the most needed neighborhoods to maximumly mitigate the negative impact of urban heat.

在全球气温升高的背景下，城市在炎热的夏季经历越来越频繁的极端高温事件。准确了解城市社区中人类室外热暴​​露的空间分布对于城市热管理非常重要。与基于地表温度的遥感不同，本研究计算平均辐射温度，更客观地表明人类热应激，以研究宾夕法尼亚州费城人类室外热暴​​露的空间分布。基于高分辨率城市3D模型和气象数据，应用SOLWEIG（太阳能和长波环境辐照几何）模型来估计平均辐射温度。这项研究进一步检查了费城不同群体社区的热暴露水平的空间分布。结果表明，费城不同种族/族裔群体的室外热暴露水平没有显着差异。一般来说，老年人通常更容易受到极端高温的影响，他们往往住在夏季室外热量较少的社区（p <0.001）。高收入人群倾向于居住在热环境更舒适的社区（p <0.001）。该研究提供了对社区间热量分布的准确理解，这将进一步有助于制定策略，将资源分配给最需要的社区，以最大限度地减轻城市热量的负面影响。