| The impervious surface is a representative surface cover in the process of urbanization,and the surface temperature is an important indicator for evaluating the urban ecological environment.The impact of impermeable surface temperature is the key to the change of urban ecological environment.Based on the remote sensing image of Changsha,this paper retrieves the surface temperature,extracts the information of the surface cover,and explores the influence mechanism of the impervious surface of the Changsha city and its changing law.The main work content is as follows:(1)Based on the atmospheric correction method,inverting the surface temperature of Changsha City,compared with the weather forecast temperature value,the errors were all less than 1?,indicating that the inversion method is reliable.The inversion results were normalized and divided into low,medium,and high temperature zones.The statistical results showed that the low temperature zone decreases by 17.08%,the medium and high temperature zones increase by 12.91%and 4.16%,respectively.The surface of the study area the temperature as a whole shows a gradual rise.Analyzing its distribution,high-temperature areas were mostly concentrated in dense urban areas.(2)Two methods of remote sensing index(NDISI)and mixed pixel decomposition were used to extract impervious surface.Combined with the highdefinition map,it was found that NDISI has removed other ground surfaces well in the extraction process.The extraction result of the mixed pixel decomposition method was doped with a large amount of bare soil,and the extraction effect of NDISI is better.According to statistics of impervious surface information,the area accounted for an increase of 17.77 percentage points,and the urban area of Changsha showed a trend of continuous expansion.(3)Regression analysis was used to fit the impervious surface and surface temperature data in the study area.The results showed that the goodness of fit of the linear function and exponential function are both above 0.8,and the impervious surface had obvious the warming effect on surface temperature.In order to analyze the phenomenon of "upward warping" in the scatter plot,the data was segmented and then linearly fitted,and the influence mechanism and change law of the two were quantitatively analyzed.The results showed that when ISF is less than 70%,ISF changes by 1% and the average change value of LST was 0.2?;when ISF increased to 70%,the change value of LST was 0.45?,and the range of change doubled.The change of the surface temperature caused by ISF changes had a sudden change. |
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