Quantitative Analysis Of The Effect Of Urbanization On Heat Sink Function

With the acceleration of urbanization,the environmental problems caused by urbanization are becoming more and more serious.Surface urban heat island(UHI)is one of the most significant environmental problems.According to the theory of source and sink in landscape ecology,heat sink landscape has significant mitigation effect on urban thermal environment(UTE),and the degree of heat sink function affected by heat source in different urbanization rate regions is significantly different.Quantitative analysis of the influence of heat sources on heat sinks in different landscape patches can provide some reference for urban planning and mitigation of urban thermal environment.Based on Landsat remote sensing image and GIS technology and the theory of source and sink landscape,this paper takes Xi'an as an example to quantitatively study the effect of heat source on heat sink function in the process of urbanization.The results show that the surface temperature(LST)increases with the increase of urbanization rate(S)and fits quadratic curve fitting.The R~2 of day and night fitting is higher than 0.8312and 0.7950,respectively.The heat sink cooling function calculated by the difference between LSTT and LSTA increases first and then decreases with the increase of S.When S is between 0.6 and 0.7,the heat sink cooling function is the best.The heat sink function can reach 1.2551?in the daytime and 1.0828?at night.The background LST source and LST sink obtained by interception method and pixel statistics method have little difference.The LST sink obtained by interception method is slightly higher than that obtained by pixel statistics method,and the LST source is slightly lower than that obtained by pixel statistics method.The background LST obtained by interception method will ignore the changes of LST in the actual environment.During the study period,the urbanization rate of 85%landscape patches increased from(0.66,1)to(0.74,1),and there were fewer landscape patches with strong cooling function.As a result,the heat capacity of the day and night heat sources showed a significant upward trend,and the theoretical heat capacity of the built-up area showed a consistent variation with the actual heat capacity.In addition,the thermal environment in the built-up area is strongly influenced by the urbanization rate of landscape patches,i.e.the proportion of heat source and heat sink.When the urbanization rate of more landscape patches is in the maximum range of heat sink cooling function,it has a significant effect on the thermal environment mitigation in the built-up area.When the landscape patches with higher urbanization rate increase,the thermal environment deterioration in the built-up area is more obvious.The new idea and quantitative model proposed in this paper can effectively reveal the influence of heat sources on heat sink function.The data errors caused by data accuracy and methods have no significant impact on the results.It can provide reference for follow-up research and has a certain reference value for the management of urban environment.