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. Mobile survey was applied to investigate the space-time characteristics of local microclimate of Beijing Olympic Forest Park and the surrounding development. The results showed that apparent differences in air temperature existed between small-scale urban areas. Microclimate of urban areas was obviously influenced by both the conditions of vegetation and environmental parameters characterizing the immediate environment of the measurement sites. Temperature differences and its spatial distribution characteristics varied with the season and between day and night. Greater difference and clearer distribution of air temperature was observed at night. During this time, temperature in the park was apparently lower than that of the surrounding built environment. The park cool island effect was exhibited with the fact that the farther from the park, the higher the temperature. However, during the day, there was smaller difference and more complex distribution of air temperature. In general, the temperature differences of the four time periods in the study area complied with the order: winter night>summer night>summer noon>winter noon, which indicated that the local heat island intensity during night was greater than during daytime, and the winter night was greater than the summer night.%目前中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可以有效地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影响因子,是调节和改善城市气候环境的理论基础.选取北京奥林匹克公园及其周边城市区域作为研究对象,采用移动路线观测法于2012年冬季和2013年夏季对研究区域内空气温度进行了测量,在此基础上对其局地空气温度的时空变化特征及其影响因子进行了分析.结果表明:即使在小尺度的城市区域内仍存在着明显的气温差异,研究区域内不同时相的温差大小为1.2~7.0℃,绿化状况以及测点周围环境特征对测点气温有着重要的影响.同时,研究也发现,研究区域内温差大小及其空间分布特征随着季节和昼夜的变化而变化.在夜晚,研究区域内的温差较大,气温分布也较为简单而明晰,此时公园范围内的空气温度明显低于周边建筑环境的空气温度,且随着与公园距离的增加,气温越高,呈现出明显的"公园冷岛"效应.然而在白天时,研究区域的空气温度差异较小,且空气温度的分布也较为复杂.研究区域内局地热岛强度总体呈现出冬季夜晚(5.9℃)>夏季夜晚(3.4℃)>夏季白天(1.8℃)>冬季白天(1.7℃)的趋势,热岛强度晚上大于白天,而冬季晚上大于夏季晚上,即城市局地热岛强度的昼夜变化大于季节变化.
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