| Global population growth and urbanization have had a significant impact on the climate change.Climate problems such as global warming threaten human survival and urban operation.Under the heat wave,urban areas will bear greater risks and the heat island effect is the embodiment of how urbanization process changing the urban thermal environment.Therefore,the purpose of carrying out researches on urban climate effect and urban spatial form is to use reasonable urban planning methods to optimize urban spatial layout and plan more sustainable and resilient cities.Based on this,this paper sorts out the relevant theories and research progress of urban climate,urban spatial complexity and urban spatial form to find the deficiency of recent researches that the quantitative study of the relationship between the urban block scale spatial layout and thermal environment lacks detailed characterization and the research on spatial layout is more based on scale but not on form.Therefore,this research combined with the thermal environment design methods,selected impact factors of ventilation,shading,pervaporation and green space and added exploratory indicators to improve the spatial layout index system and research framework of urban blocks completely.Secondly,the remote sensing inversion method was used to measure the annual average surface temperature in the central urban area of Xi’an in year of 2009,2014 and 2019.Through the analysis of the heat island,the heat island blocks were identified and the thermal environment pattern characteristics of the central city and urban blocks of Xi’an were analyzed from the perspective of the scale of the heat island intensity areas,the spatial structure of the cold or heat island and the spatial and temporal changes of heat island intensity.Thirdly,in order to analyze the correlation between the thermal environment and spatial layout of the urban blocks,this research uses the single factor analysis and partial correlation analysis to reveal the influencing factors and mechanism of the spatial layout of the urban blocks on the heat island intensity in the central Xi’an from the dimensions of architectural space layout,road space distribution and green space pattern.Finally,the spatial layout model is extracted as the reference for the construction of cool blocks by selecting significant factors,analyzing the characteristics of various indexes of the low,medium and high intensity cold island blocks in architectural space layout,road space distribution and green space patterns and typical cases of the low,medium and high intensity cold island blocks to summarize the spatial patterns of low,medium and high intensity blocks and to cope with the high temperature weather.Through the research,it is found that,first of all,the cold and hot areas show a circle difference in central Xi’an.Both the central city and the urban blocks of Xi’an have shown a warming trend over the years.The heat island area has been expanding and the cold island area has been shrinking year by year.The proportion of heat island intensity area has shifted to higher intensity.The temperature difference between urban and rural areas is large and the heat island effect is significant.The composition structure of heat island intensity in cold and heat island blocks is different,but both types of blocks show an increasing trend of heat island effect,moreover,the cold island blocks are more stable than the heat island blocks.Secondly,there is a strong partial correlation between the spatial layout of the urban blocks in the dimensions of space layout,road network and green space and the surface temperature of the urban blocks which is embodied in the scale,shape,level of building space,road network space and green space.Lastly,from the differences in the spatial layout of urban block spatial layout in low,medium and high intensity cold island blocks,the block spatial layout model is summarized to provide reference for cooling blocks planning in different intensity urban blocks. |
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