| Since the reform and opening up,with the rapid acceleration of urbanization and industrialization,the continuous expansion of cities and the evolution of urban development pattern,China has led to a series of urban ecological and environmental problems,such as water pollution,atmospheric aerosol pollution,urban heat island effect and sharp reduction of biodiversity.At present,the more prominent urban ecological environmental problems are mainly represented by atmospheric aerosol pollution and urban heat island effect,which have become the main representatives that seriously endanger the living environment,health and safety of urban people and the development of society.Although many scholars have carried out quantitative research on urban heat island effect and atmospheric aerosol pollution at different spatial scales such as global,national and regional,domestic and foreign scholars have not obtained a systematic and comprehensive understanding of them.Therefore,it is urgent to carry out systematic research on the temporal and spatial patterns of urban heat island effect and atmospheric aerosol pollution and their impact on land use,which has become a research hotspot in relevant fields such as climatology,ecology,urban planning and geography and has also been a key concern of government policymakers,environmental planners,geographers and other scholars.It is guided by the theories of ecology,economics and geography,this study used multi-source spatial data such as land use / land cover data,Landsat series product data,MODIS series product data,meteorological data,night light data,and digital elevation model from 2000 to 2020 and other auxiliary data.Based on the inversion of land surface temperature and aerosol optical depth,the spatial and temporal evolution patterns of the interannual and seasonal urban heat island effect and aerosol optical depth in Nanchang were quantitatively analyzed.In addition,the spatial and temporal coupling characteristics of the relationship between the two were comprehensively analyzed from the perspectives of ecology,geography,economy,and so on.At the same time,the normalized vegetation index,population density and other characterization factors were selected from the four aspects of topography,meteorology,land cover and human activity intensity,and the diversity index was combined as the influence factor,so as to analyze the scale effect of heat island effect,aerosol optical depth and its influence factors,and identify the best research scale.Then,from the perspective of multidimensional time,the synergistic relationship between the characterization factors and urban heat island effect,aerosol optical depth and their coupling coordination degree was analyzed,and the dominant factors were identified.Finally,based on the type,structure and diversity of land use,the response of land use was analyzed,which provides decision-making support for the formulation of a reasonable urban planning of Nanchang,the construction of a suitable,healthy and safe living environment,and the monitoring,regulation and prevention of climate change.The main conclusions of this paper are as follows:(1)From 2000 to 2020,the phenomenon of "heat island" in Nanchang had been alleviated,showing significant seasonal differences,that was,winter>spring>autumn>summer,and there was obvious spatial heterogeneity.In addition to Xinjian District and Honggutan district,the phenomenon of "heat island" in other administrative regions such as Donghu District,Qingshanhu district had intensified.At the same time,high-high agglomeration areas(H-H)mainly occurred in Donghu District,Qingshanhu District,Honggutan District,Nanchang County,etc.The spatial distribution showed a multi center distribution pattern and radiates outward.The urban heat island area was mainly concentrated in the urban built-up area,and the green island area was mainly concentrated in the vegetation cover and water area.(2)From 2000 to 2020,the atmospheric aerosol pollution in Nanchang had been alleviated,showing wavy fluctuations,and there were obvious seasonal differences,that was,summer > spring > autumn > winter,and there were significant regional differences in spatial distribution.The aerosol optical depth of each administrative region presented a change state of "rise-decline-rise-decline".The high-value agglomeration state was mainly concentrated in the low-altitude Honggutan District,Nanchang County,Qingshanhu district and part of Xinjian district,and the low-value agglomeration state was mainly concentrated in the high-altitude Meiling mountain area and the low-altitude Poyang Lake border area.(3)The strongest scale of urban heat island effect,atmospheric aerosol concentration,terrain,meteorology,land use / cover and human activity intensity in Nanchang was 2km×2km.(4)The urban heat island effect and atmospheric aerosol concentration in Nanchang from 2000 to 2020 did not exist in isolation,but had a coupled relationship of mutual dependence,interdependence and interaction.From the four perspectives of ecology,geography,economics and systematics,it was found that there was a significant spatiotemporal coupling relationship between the intensity of the urban heat island effect and the aerosol optical depth.(5)With the acceleration of urbanization and industrialization,the spatial pattern of built-up areas had changed,resulting in significant primary and secondary changes in the factors affecting the spatiotemporal pattern of the urban heat island effect,atmospheric aerosol concentration and their coupling relationship,and land use / land cover plays a crucial role.Through the analysis of OLS,LSR model and GWR Model,it was found that the contribution degree of influencing factors to urban heat island effect in each period was land cover > climate factor > human activity intensity >terrain factor,and the influence of land cover would be more and more active.Through RF model analysis,it was found that the number of dominant factors affecting the aerosol optical depth in each period presented a trend of "decline-invariant-decline-up",but it was most seriously affected by land cover.Through principal component regression model analysis,it was found that the intensity of human activities,land cover and climate conditions had become the dominant factors affecting the spatiotemporal coupling relationship between the heat island effect and atmospheric aerosol concentration in Nanchang,and the influence of land cover was also important.(6)Nanchang’s heat island area,heavily polluted areas of atmospheric aerosol concentration,and extreme coupling coordination were mostly distributed in construction land,while the green island area,areas with mild atmospheric aerosol concentration pollution,and extremely uncoordinated states were mostly distributed in woodlands,waters and unused land.The heat island area,heavily polluted areas of atmospheric aerosol concentration and extreme coupling coordination gradually shifted from cultivated land to urban construction land.From the perspective of time series,the spatial layout of land use types will become simpler and simpler,which will help alleviate the urban heat island effect,atmospheric aerosol pollution and improve the coupling relationship.In conclusion,this paper comprehensively and systematically studied the spatial and temporal patterns evolution characteristics of urban heat island effect and aerosol optical depth in Nanchang City from the long-term scale,using Landsat series product data,MODIS remote sensing data,land use/land cover data and other multi-source spatial data.Moreover,it comprehensively explained the characteristics of the coupling relationship between the two in space and time from the perspectives of ecology,geography,economy,etc.At the same time,the synergistic relationship between urban heat island effect,aerosol optical depth and coupling coordination degree and meteorology,terrain,land cover and human activity intensity was compared and analyzed from the perspective of multi-dimensional time.Moreover,the response of land use was analyzed from three aspects of land use type,structure and diversity,which has certain theoretical and practical innovation significance.Furthermore,under the background of global warming and serious air pollution,the results of this study can provide a certain reference for monitoring,regulating,preventing and controlling climate change in Nanchang City and similar cities,as well as formulating reasonable urban planning and building a healthy,suitable and safe living environment. |
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