| Impervious surface is an important product of urbanization,and also a significant feature that distinguishes urban areass from non-urban areas.Impervious surface plays a key role in measuring urban development,and this type of land cover has brought a lot of adverse effects on urban ecological environment.Based on the Landsat series of six phase satellite remote sensing images(1994 ?2019),this paper puts forward the Endmember Selection Optimization Schemes(ESOS)and Post-Processing Models(PPM)on the pixel and sub-pixel scales,from vegetationimpervious surface-soil(V-I-S)model and the linear spectral mixture analysis(LSMA)model.With the unmixing method for mixed pixels,the impervious surface in the Guangdong-Hong Kong-Macao Greater Bay Areasuccessfully has been extracted.Moreover,the characteristics of urban development in the study area are expounded by using the weighted average center method and standard deviation ellipse method in the method of geographic correlation analysis.Combined with MODIS urban surface temperature products since 2000,the variation trend of urban high temperature area is analyzed,the surface temperature at different impervious surface density levels has been counted,and the seasonal difference of correlation between them has been analyzed.At the same time,the geographical positions,the moving distances,and the distance between the geographical weighted average center of impervious surface and urban surface temperature over a long time series are calculated,and the influence of the research scope on the thermal environmental effect of impermeable surface is analyzed.The results show that:(1)In the extraction of the impervious surface on sub-pixel scale,the ESOS based on pixels scale,using the correlation spectrum index(normalized difference vegetation index,normalized construction index,the drought index of bare soil,as well as the hat or cap with tassels transformation after the first and the third component of the normalized results),can quickly and accurately select target like yuan,determine the target "pure" pixels.(2)The PPM can greatly improve the accuracy of the extraction results of impervious surface fraction by LSMA,and improve or even completely solve the problem of impervious surface fraction being overestimated in the lower density impervious surface and underestimated in the impervious surface fraction,namely,the problem of underestimation in the high value and overestimation in the low value.(3)In the long time series,there is a small change in the direction of urban development.Among them,the urbanization level of Guangzhou(central and southern development is given priority),Shenzhen city,Hong Kong Special Administrative Region and Macao Special Administrative Region is relatively high.Zhuhai city,Zhongshan City,Foshan City and Dongguan city have medium urbanization level;Jiangmen,Zhaoqing and Huizhou have a low level of urbanization.(4)The correlation between impervious surface and urban surface temperature has obvious seasonal characteristics.The correlation is stronger in summer and weaker in winter.The greater the impervious surface fraction,the stronger the impervious surface heating capacity per unit area.The higher the temperature is,the stronger the impervious surface heating capacity per unit area is.(5)The results of urban thermal environmental effects of impervious surface will be affected by the study area.The study area is large and the geographical position of impervious surface changes obviously in urban high-temperature area.The study area is small,and the change of the high temperature area area caused by the change of the geographical location of the high-density area of impervious surface is small,which is insufficient to explain the correlation between the two,and other relevant data are needed to assist,such as the urban structure,urban construction materials and urban geographical location... |
PDF Full Text Request