Thermal Effect Of Urban Spatial Form In Mountain City

21 Century is the world of city,we are now experiencing the greatest revolution on the Earth-the rise of the city.Cities are expanding their scale at an unprecedented rate,and a steady stream of elements of population and energy concentrate in urban areas,large numbers of artificial construction and of fossil energy combustion,significantly affect and change the original city spatial form and energy balance,which highlights the urban ecological environment problems.Among them,the most common is the urban heat island effects.Which changed the local climate,destroyed the balance of the original ecosystem,and increased the energy consumption and environmental pollution.More seriously,the intensification of the heat island effect accelerates the trend of global warming.Resulting in heavy rains,drought,heat waves and other extreme weather disasters in recent years,which has been a big threat to urban security and human sustainable development.In recent years,scholars have been growing concern about urban heat island,and have been doing a lot of research on the mechanism and mitigation strategies of the heat island,and obtained many achievements.While in thermal environment effect of urban spatial form,most of the existing researches are based on a certain factor of urban spatial morphology,and study the coupling relationship between spatial form factor and thermal environment effect,lacking of systematic and instructive.Product as the comprehensive function of material and non-material elements in the city space,the urban heat island needs to clarify the mechanism of interaction between the elements and the thermal environment from overall level of the system,so as to guide the implementation of the planning.Based on the review of the existing urban spatial thermal environment research,this paper integrated Measured Data and Satellite Remote Sensing Data,using the relevant thermal environment simulation software(SUEWS,FLUENT),combined with the urban spatial form classification scheme based on local climate zones(LCZ).From four aspects of research,technical construction-spatial index analysis-morphological classification-empirical analysis-optimization control,focusing on the study and finding the coupling relationship between urban spatial form and thermal environment in mountain city context.Based on these,the author constructs the strategy of optimizing and regulating the thermal environment of mountainous cities,and provides practical guidance and theoretical basis for the construction of ecological and livable mountain cities.The specific contents are divided into the following parts:Chapter 1,Introduction.Which briefly introduces the background of this research,studies the necessity and urgency of the problem,emphasis on summarizing and introducing the relevant theory concept theory and related research,and puts forward the purpose and significance of this research.Chapter 2,Technical Framework.This chapter focuses on the application of technical methods,processes and simulations in detail,and constructs the evaluation and optimization system of thermal environment effect of mountain city spatial form.Chapter 3,Spatial Index Analysis.According to the quantitative method of urban spatial form and the three-dimensional spatial morphological features of the city that mainly reflected by urban spatial form index,and basing on the logistic framework of the literature review-empirical application and mechanism analysis.This paper explores the coupling relationship between urban spatial form index and thermal environment effect from three aspects,plane shape index(density,underlying surface),vertical shape index(height,wind area,roughness),comprehensive form index(sky view factor,street aspect ratio,floor area ratio),Using the literature review-empirical application-mechanism analysis logical framework in turn.Chapter 4,Morphological Classification and Empirical Analysis.First,based on the study of the relationship between urban spatial form parameters and thermal environment in Chapter 3,the fourth chapter extracts five key spatial morphological indices that can characterize urban spatial form and influence thermal environment(building density,sky view factor,height of roughness elements,impervious surface fraction,street high aspect ratio).Referring to the classification scheme of urban spatial morphology of LCZ,the system is used to classify the spatial form of mountain city,then superimpose the surface temperature of different seasons,analyze and evaluate the coupling relationship between the space form types and the thermal environment,and extract the best spatial form suitable for the thermal environment of mountainous cities.Second,based on the coupling relationship between urban spatial form and thermal environment,using measured data and satellite remote sensing data to analyze natural surface covered by green space and water body.In this way,the internal elements of the spatial distribution and composition of each urban spatial form as well as the internal mechanism of the thermal environment effect are further revealed.Which provide the basis for optimal strategy of the thermal environment effect of the urban space form.Chapter 5,Thermal Environment Control.On the basis of spatial index analysis and empirical analysis,aiming at the main factors of heat source and the thermal environment,the thermal environment optimal control strategy of the spatial form of mountainous city is put forward in the spatial form and the factor layout level,and the thermal environment optimization and control system of the mountainous urban space thermal environment is constructed.which provides theoretical basis for constructing eco-friendly and environment-friendly cities.Chapter 6,Conclusion.Summarize the research,reflect the deficiencies in research work,and look forward for future work.