基于局地气候区分类的城市热环境时空变化特征及其主要景观驱动因子研究

At present, conflicts between urban development and climate environment are becoming increasingly apparent under rapid urbanization in China. The negative effects of urban heat island on living environment could be greatly mitigated by appropriate urban planning and landscape design strategies. Revealing the dynamic mechanism and controlling factors of urban outdoor thermal environment is the necessary theoretical preparation for regulating and controlling urban climate environment. Taking Hangzhou as an example and based on the local climate zones classification system, this project examines the temporal and spatial variation of intra-urban outdoor thermal environment by using a long-term urban network of air temperature sensors set-up in different local climate zones. The effects of both the composition and structure of land cover on urban outdoor thermal environment will then be further investigated, using correlation analyses and multiple linear regressions. The composition and structure of land cover features are measured by a series of landscape design parameters, which are calculated from the data of high-resolution land cover maps and on-site measurements. Based on the above results, the evaluation and predicting models for urban thermal environment with landscape parameters as an integrating index are also put forward. As a theoretical and practical guide for improving outdoor thermal comfort and reducing building cooling energy use, the results will provide theoretical basis and advices on appropriate strategies for urban planning and landscape design to improve outdoor thermal environment.

目前我国正处于城镇化快速发展阶段，城市、气候和环境间的矛盾日益凸显。适宜的城市规划和景观设计策略可以有效的缓解热岛效应等城市气候问题对人居环境带来的负面影响。揭示城市户外热环境的时空变化格局及其驱动机制，是调节和改善城市气候环境的理论基础。本项目拟针对具有特定气候条件和城市形态的杭州市，基于局地气候区分类系统，建立起微气候固定监测和移动观测体系，对城市户外热环境进行长期的监测，从而全面系统的揭示城市热环境的时空变化特征；并通过相关性分析和回归分析探明不同景观下垫面因子与户外热环境的定量关系，明确城市户外热环境的关键景观驱动因子；在此基础上构建耦合多项景观指标的城市户外热环境的评价与预测模型，为城市规划和景观设计过程中调节和改善城市气候环境提供科学依据和决策参考。项目的研究成果对提高城市户外热环境安全和舒适度水平、降低建筑能耗具有重要的理论价值和实践意义。

对于高密度城市来说，在人类热舒适密切相关的局部尺度上探究城市气候驱动因子是改善城市热环境的首要任务。本研究引入了景观分类系统局地气候区（LCZ）作为研究城市热环境的一种科学方法。基于局地气候区分类系统，本项目研究了杭州地区的城市土地覆盖组成和城市结构对城市户外热环境的影响。实验选取了4种常见的局地气候区（LCZ2、LCZ4、LCZ5、LCZ9）作为研究对象，对四个局地气候区内热环境进行了实地测量与分析。结果表明，在晴朗、平静、干燥的白天，夜间平均气温差异达2.7℃，局地气候区的温度高低排序为LCZ 2＞4＞5＞9。在夜间，通过120 m半径尺度范围内的透水表面比率和建筑表面比率能最好地解释温度变化。此外，还可观察到邻近绿地对城市夜间冷却的影响。实验表明，同一局地气候区内微尺度气温差比局地气候区类型之间的温差小，证实了局地气候区概念的适用性。此研究成果对指导高人口密度城市的城市规划和居住景观设计，及改善城市热岛，节约能源，减少排放具有一定的指导意义。