The Urban Thermal Environment Analysis And Simulation Based On Remote Sensing And CFD Technology

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.