Impacts Of Green And Blue Landscape On Mitigating The Urban Heat Island Effects

39 parks and 45 rivers in central urban area of Shanghai. China were selected along with land surface temperature derived from Landsat ETM+thermal infrared band and landscape pattern metrics calculated by land cover and land use data, were employed to explore the impacts of landscape structures of green and blue and their surrounding landscape patterns on their cooling effects, which were measured by maximum park cool island intensity, maximum cooling distance, and maximum cooling area. These findings were helpful for landscape and urban planning. The results were as following:(1) In spring, no relationship was found between park size and its land surface temperature. In summer, a negative logarithmic relationship existed between park size and its land surface temperature.(2) Most of the parks were cooler than their surroundings. Park size was valuable to assess the park cooling effect. Maximum cooling distance and maximum cooling area were more effective to quantify the park cooling effect. Moreover, in a limited space in urban area, the small parks should be bulit to improve the cooling efficiency of green.(3) Both in spring and summer, surrounding landscape patterns influenced the cooling effect of parks both at class and landscape levels. The man-made urban land use types, especially their proportion and dominance, negatively affected park cooling effect, but enhanced shape complexity could alleviate the adverse impact of urban land use types on cooling effect. However, the surrounding natural and semi-natural landscape types positively impact park cooling effect.(4) No relationship was found between river size and its land surface temperature. In spring and summer, a negative linear relationship existed between river size and its land surface temperature in the urban area. Maximum cool island intensity was more effective to quantify the river cooling effect. River size and width in spring had more stronger effect on maximum cool island intensity than those in summer. Moreover, large size and width of river had large maximum cool island intensity.(5) Most of the rivers were cooler than their surroundings. River size and width are helpful to assess the river cooling effect.(6) Both in spring and summer, surrounding landscape patterns influenced the cooling effect of rivers both at class and landscape levels. Rivers with large size and width within the area with higher shape complexity tend to achieve better cool island intensity. Size and width of rivers had little influences on the cooling distance, but high shape complexity of the surrounding landscape could also promote the extension of cooling distance.