| With the rapid development of the global economy,urbanization is accelerating and urban space is spreading rapidly.However,although this overly crude urban scale growth model has promoted the rapid development of urban economy,the frequent human-land interaction process has led to changes in the large-scale land use coverage pattern,and the natural landscape has been gradually replaced by the artificial landscape,leading to a series of environmental problems,among which the urban heat island effect is the most obvious.The urban heat island effect is usually manifested as the phenomenon that the temperature in urban areas is higher than that in rural areas.The urban heat island effect not only destroys the climate environment of urban areas,but also affects the safety and comfort of living environment,and poses a great threat to human health.Therefore,it is of great significance to understand the spatial and temporal characteristics and driving mechanisms of the urban heat environment,and to develop mitigation and adaptation measures for the heat environment effect in specific areas to build a comfortable and livable urban habitat.Nanjing,as a traditional typical "furnace city",is a representative area for studying the effects of urban thermal environment.Therefore,this paper takes Nanjing as an example to carry out research on the urban thermal environment effect,objectively reveal the time-series change law of urban heat island effect,explore the response mechanism of urban thermal environment to the change of landscape pattern,and on this basis,propose macroeconomic regulation and control suggestions to cope with the extreme high temperature in Nanjing,so as to provide an effective theoretical basis for scientific formulation and adjustment of urban planning and development strategies,and improve the urban thermal environment.The main conclusions are as follows.(1)The urban heat island effect in Nanjing changed significantly between 2000 and2021,and was generally in an aggravated state.Heat island and strong heat island patches show a "pie-like" expansion,with the area share rising from 6.48% to 41.89%,an increase of 35.41%,and most of them are in and around built-up areas;green island and strong green island patches show a decreasing trend,with the area share falling from 37.38% to18.84%,a decrease of The trend of the distribution of each type of heat island patches was studied by the standard deviation ellipse method,and it was found that the spatial distribution of heat patches mainly showed a "southeast-northwest" distribution pattern.As time goes by,the distribution direction of thermal landscape in the heat island and strong heat island areas is tilting to the southeast;the distribution direction of thermal landscape in the normal area is tilting to the southwest;the tilting trend of thermal landscape azimuth in the green island and strong green island areas is also different,among which the green island shows a "southwest first and then southeast" evolution,while the strong green island shows a "southeast first and then southwest" evolution.Green Island shows a "southwest then southeast" trend,while Strong Green Island shows a "southeast then southwest" trend.The spatial coupling model was used to analyze the coupling between the built-up area and the heat island patch expansion,and it was found that the coupling types between the built-up area expansion and the urban heat island patch were mainly lightly coupled and lightly uncoupled,among which the main urban area of Nanjing was mainly uncoupled unit agglomeration,and the further away from the main urban area,the more coupled the two expansion types showed.(2)From 2000 to 2021,the types of land use in Nanjing have changed significantly,mainly in the form of a large reduction in agricultural land and a sharp increase in the area of construction land.In addition,the proportion of other land types shifting to construction land is greater between 2010 and 2021 than between 2000 and 2010,which verifies that the urbanization rate of Nanjing is further accelerated and the level of urbanization is further increased between 2010 and 2021.The "Source-Sink" Landscape Index(LI)analysis shows that the number of districts and counties in Nanjing with "weak" LI is the highest between 2000 and 2010 and between 2010 and 2021.This indicates that with urbanization,the "source-sink" landscape structure of most districts and counties is contributing to the intensification of the heat island effect;the changes in LI levels show that the development of suburban areas is often contributing to the heat island effect,reflecting the deterioration of the regional environment.(3)A total of 10 natural and anthropogenic disturbance factors closely related to the urban thermal environment were selected and their relationship with the urban thermal environment was simulated by using spatial Principal Component Analysis(PCA).The results showed that the contribution of human disturbance factors to the aggravation of heat island formation was significantly greater than that of natural factors,and for every1 unit change of human disturbance factors and natural factors among the 10 influencing factors,the overall effect of regional temperature increased by 0.727℃.On this basis,the measures to mitigate the effects of urban heat environment are proposed:(1)reasonable urban planning layout.Promote multi-center city construction,increase the area of nonconstruction land,set up ventilation corridors or construct high-rise buildings,etc.;(2)Reduce anthropogenic heat emission.Distribute industrial land with outside the built-up area,low-carbon travel,etc.;(3)Increase the degree of urban water bodies and vegetation coverage.Build urban parks and artificial lakes,expand roadside green areas,etc.Figure [23] Table [22] Reference [120]... |
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