Abstract: Urban green-blue infrastructure (GBI) in blocks plays an important role in adapting to climate change by solving urban thermal environment and improving thermal comfort. Based on high resolution images of Three Hills and Five Gardens Area in Beijing, morphological spatial pattern analysis (MSPA) was used to quantify the pattern of urban GBI. GBI types included branch, bridge, core, edge, islet, loop, and perforation. We analyzed the correlation between GBI’s composition and structure and land surface temperature, and GBI’s thermal mitigation ability and its influencing factors. In Three Hills and Five Gardens Area, the area ratio of GBI was 60.61%, while the correlation between mean surface temperature (T_m) and GBI’s area ratio was significantly negative. The correlation between T_m and ratio of trees was greater than that with water body or grassland. The relevance was higher between T_m and the ratio of core area than with perforation area, edge area, loop area, bridge area and branch area in turn. Thermal mitigation of GBI was significantly affected by its spatial pattern. In the blocks with core area ratio of GBI over 10%, T_m was negatively correlated with the proportion of core area and perforation area, but not with that of tree, grassland, and water. In the blocks with core area ratio of GBI between 1% and 10%, T_m was negatively correlated with trees occupying area, loop area, bridge area and branch area. In the blocks with core area ratio of less than 1%, T_m was negatively correlated with edge area. In addition to taking green space cover types into consideration, the planning and design of GBI in future blocks should be closely combined with the characteristics of GBI layout, which can be implemented by the following measures: enlarging the scale (increasing the width of peripheral edge area around existing GBI patches), enhancing connectivity (connecting existing GBI patches to construct blue-green corridor), optimizing the configuration of activity fields (appropriately increasing activity fields within the core area), in order to form the nature-based thermal mitigation solutions for blocks. The results can enhance the understanding of relationships between GBI pattern and thermal mitigation characteristics in urban blocks, and provide reference for the mitigation of heat island effect and thermal comfort improvement at urban block scale.

Key words: urban green-blue infrastructure, morphological spatial pattern, nature-based solution, urban thermal environment, Three Hills and Five Gardens Area.