【作者】 王翠云；

【导师】 王乃昂；

【作者基本信息】 兰州大学 ， 环境科学， 2008， 博士

【摘要】 自1818年Lake Howard对伦敦城区和郊区的气温进行对比观测,发现城区气温比其郊区气温高,从而提出“城市热岛”的概念以来,城市热环境问题一直备受关注。特别是近年来,在全球增温和高速城市化的背景下,城市热环境被认为是主导整个城市环境的要素之一,对城市微气候、空气质量、能源消费结构以及公共健康等方面产生深远影响,城市热环境是城市空间环境中存在的热力场的综合表现,通过对城市热环境的研究可以揭示城市空间结构、城市规模的发展变化。此外,随着人们对生活舒适度、身体健康、安全程度要求的进一步提高,城市热环境已成为城市社会经济可持续发展的基础支撑条件,良好的城市热环境也是城市人居环境生态化的重要标志。提高人们对城市热环境的认识,掌握城市热环境表征因子和影响因子的空间分布以及定量研究各影响因子对城市热环境影响是实现可持续发展的重要环节。造成城市热环境恶化的主要原因是城市土地利用/覆盖类型的变化和城市人为热释放,其中城市土地利用/覆盖类型的变化(主要表现为城市建设用地的扩展和绿地的减少)是最为首要的因子。因此,基于现有的研究技术条件,本研究首先在遥感数据的支持下,以1986年、2002年和2007年的Landsat TM/ETM+遥感影像为研究数据源,从宏观层面分析不同土地利用/覆盖类型(建设用地、绿地和水域地)与城市热环境之间的互动关系。然后,利用CFD技术从微观层面,分别以水泥和粘土作为下垫面,模拟住宅小区热场的分布状况,进一步说明不同下垫面类型对热环境的影响。在国内,作者首次尝试性的将CFD技术应用到城市住宅小区热环境的模拟,为城市热环境微尺度的模拟提供了新的思路。不同土地利用/覆盖类型与城市热环境之间的互动关系分析的结果表明:随着温度级别的升高,建设用地面积比重明显升高,水域地的比重逐渐下降,绿地则与建设用地和水域地两者不同,呈现出先增加后降低的变化趋势。这表明建设用地在城市热环境效应中的贡献率是最大的;绿地对较低温区和中温区的贡献最大,而对低温区和高温区的影响最小;而水域地对低温区的贡献最大。利用CFD软件对住宅小区热环境模拟的结果表明:以粘土为下垫面的温度场中低温区的分布面积明显多于以水泥为下垫面的温度场中低温区的分布面积,而以粘土为下垫面的温度场中的高温区较以水泥为下垫面的温度场高温区不仅面积上小,而且温度值也相对较低。由此可见,绿地、水域地、粘土因其有较高的比热容和较低的热传导系数,以其作为下垫面,可以降低城市温度,改善城市热环境。更多还原

【Abstract】 In 1818, Lake Howard came up with the concept of "urban heat island", after comparing the temperature of the city and the suburbs of London, and finding that temperature in the urban is higher than the suburbs. Since that, the problem of urban thermal environment has been concerned all the time. Especially in recent years, under the background of global warming and high-speed urbanization, the urban thermal environment is considered as one of the leading elements of influencing all the urban environment, and has a far-reaching effect on urban public health, air quality, energy consumption, and so on.Urban thermal environment is the overall performance of the thermal force field existing in the urban space environment. The construction of the urban space, the developments and changes in the size of the cities can be revealed by the research of urban thermal environment. In addition, with the further improving for the requirements of the people’s living comfort, body health, safety, urban thermal environment has become a basic supportive condition for the social and economic sustainable development of the cities; a good urban environment is also an important ecological sign for urban living environment.It is an important link for the realization of the sustainable development to raise the city thermal environment awareness of the citizens, to master the spatial distribution of the characterized and impact factors of urban thermal environment, and to research quantitatively the effects of all the impact factors on urban heat environment.Urban thermal environmental degradation is mainly due to both the types change of land use/land cover and urban anthropogenic heat release, the former of which (mainly for the expansion of urban construction lands and the reduction of green space) is the most prime factor. Therefore, in the macro-level, firstly, this paper analyzes the interaction between the urban thermal environment and different land use / land cover types (construction land, green land and water land), with the support from remote sensing data, based on existing research technology. Then, using the cement and clay as the underlaying surface respectively, it simulates the hot field distribution of the residential sites, and further explains the effects of different types of underlaying surface on the thermal environment, according to the CFD technology in micro-level. Domestically, it is the author who firstly attempted to apply the CFD technology to the thermal environment simulation of urban residential area, and provided a new way of thinking to simulate the city thermal environment in micro-scale.The analytic results of the interaction between different land use / land cover types and urban thermal environment showed that: with the increasing of temperature levels, the proportion of construction land area increased significantly; that of waters gradually decline; differential from those two kinds, green land showed a changing trend of decrease after the first increase in rates. This shows that the construction land contributes the greatest to the urban thermal effect; green land influences the most on the lower and the middle temperature area, and minimally impacts upon the low and high temperature area, while the waters makes the largest contribution to the low area.The simulation results of the thermal environment residential quarters using CFD software showed that: the distribution area of low-temperature fields in the clay underlaying surface is obviously more than the cement, and not only the area of the high temperature area in clay underlaying surface is smaller than the cement, but temperature value is also relatively lower.Thus, because the green land, waters, the clay have a higher heat capacity and a lower thermal conductivity, the underlaying surface made of them can reduce the urban temperature, and improve the urban thermal environment.更多还原