Climate change adaptation is crucial to be addressed with specific considerations at smaller spatial scales, such as the district level, not only at the national or municipal levels. Computational fluid dynamics (CFD) analysis is particularly effective in evaluating local heat-related measures, with accumulated knowledge on future microclimate projections. In this context, it is desirable to project not only future weather conditions but also urban forms, aligning with the development trends for each scenario, and to understand the effect of each change on microclimates. Therefore, this study conducted a future microclimate simulation that reflected both changes in building stocks and temperature rises based on the Shared Socioeconomic Pathways (SSP) and Representative Concentration Pathways (RCP), focusing on an urban central district in Japan. The changes in building stocks by SSP were determined through expert judgment by researchers, including members engaged in urban planning in the district. The temperature rises by SSP/RCP were determined by referencing a statistically downscaled climate scenario dataset from the General Circulation Model (GCM). While the results showed that air temperature (AT) increased by up to 2.7 °C due to inflow temperature rises, mean radiant temperature (MRT) decreased by up to 7.5 °C due to changes in building stocks by the 2090s above the road at 14:00 on a representative summer day. It was suggested that while future temperature rises directly affected the district-scale AT, changes in building stocks had the potential to mitigate their effects on human comfort and heat-related risk. These findings emphasize the importance of aligning these future changes based on the same scenario framework in microclimate simulations and contribute novel insights to the development of this approach.

中文翻译：

---

SSP/RCP下未来城区的微气候模拟：反映建筑存量和气温上升的变化


适应气候变化至关重要，需要在较小的空间尺度（例如地区一级，而不仅仅是国家或市一级）进行具体考虑。计算流体动力学 (CFD) 分析在评估当地与热量相关的措施方面特别有效，可以积累有关未来微气候预测的知识。在这种背景下，不仅需要预测未来的天气状况，还需要预测城市形态，与每种情景的发展趋势保持一致，并了解每种变化对小气候的影响。因此，本研究基于共享社会经济路径（SSP）和代表性集中路径（RCP）进行了未来微气候模拟，重点关注日本的城市中心区，反映了建筑存量的变化和气温上升。 SSP的建筑存量变化是由研究人员（包括该区从事城市规划的成员）经过专家判断确定的。 SSP/RCP 的温度上升是通过参考大气环流模型 (GCM) 中统计缩小的气候情景数据集来确定的。结果显示，由于流入温度升高，空气温度 (AT) 上升了 2.7 °C，而由于 2090 年代道路上方建筑物数量的变化，平均辐射温度 (MRT) 下降了 7.5 °C，为 14 :00 在一个典型的夏日。有人建议，虽然未来气温上升直接影响地区规模的空调，但建筑存量的变化有可能减轻其对人类舒适度和热相关风险的影响。 这些发现强调了在微气候模拟中基于相同情景框架调整这些未来变化的重要性，并为这种方法的发展提供了新的见解。