Research On The Influence Of Impervious Surface On Land Surface Temperature Based On Morphological Factors

The expansion of urban construction areas has caused environmental pollution,heat island effect and other problems,which have adversely affected the ecological environment and the overall livability of the city.The severe cold area not only faces the problem of urban heat islands,but also faces the problem of winter cold protection,which make urban thermal environment in severe cold area more complicated.Taking Harbin as an example,this paper aimed to explore the spatial-temporal relationship between land surface temperature and urban impervious surface in severe cold area.It was expected to provide guidance for urban planning and design to improve the urban thermal environment from the perspective of morphology.In this paper,Landsat remote sensing data were used to retrieve the surface temperature in 2007,2011 and 2017.Based on spectral index,the decision tree method was used to classify the lands.The distribution law of urban land cover and surface temperature was analyzed from the perspectives of spatial loops and annual and seasonal changes.In addition,the size,shape complexity,patch density and spatial aggregation of impervious surface were extracted by the grid method.From the aspects of the morphological factors,the relationship between impervious surface and land surface temperature was analyzed.The results showed that there was a strong spatial and temporal correlation between them.Along the urban-rural gradient,it was found that there was a significant positive correlation between mean land surface temperature and impervious surface coverage in winter and summer,and the change of urban surface temperature was more sensitive to the growth of impervious surface.In the highdensity impervious surface area,the cooling effect of vegetation would be delayed;in the low-density area(the third and fourth ring roads),the non-impervious surface could play its cooling role due to the scale effect.In general,the fitting of impervious surface morphological factors and land surface temperature in summer was better than that in winter.The size of impervious surface was linearly positively correlated with the land surface temperature,the spatial aggregation was exponentially positively correlated,the patch density was linearly negatively correlated,and the shape complexity had little effect on the surface temperature in summer.With the artificial interference of district heating and the impact of cold climate,only the spatial aggregation was linearly weakly positively correlated with land surface temperature in winter.According to the percentages of impervious surface,the fourth ring zones of Harbin were divided into four levels for further analysis.The study found that impervious surface had a greater impact on land surface temperature in the highdensity area.For every 10% increased in impervious surface,the surface temperature rose by 1.2°C;for every 0.1 scale of shape complexity,the surface temperature dropped by 1.9°C;for every unit of space aggregation,land surface temperature rose by 0.55°C.Therefore,it was recommended to adopt urban impervious surface with scattered,small-scale and complex edge contours in urban landscapes and planning so as to have a healthier and more comfortable urban living environment.In addition,due to the small solar elevation angle and the less surface heat obtained in the urban high-density construction area,the correlation between morphological factors and surface temperature in winter was opposite to that in summer.