Objective The micro-scale environment is a very important human-scale outdoor space unit. Exploring the influence mechanism of micro-scale underlying surface type and pattern on microclimate is the theoretical basis of improving urban thermal environment with the help of landscape design strategies.
Method Through field measurements, differences of daily air temperature (AT) and relative humidity (RH) among seven typical underlying surface types of urban residential green space, and correlations between daily AT and RH and various micro-scale underlying surface patterns as explained by landscape metrics were analyzed.
Result During the four seasons, there were various differences in daily AT and RH among the seven underlying surface types, and the order of seven types varied seasonally. Overall, high canopy-density vegetation and water body type always had prominent cooling and humidifying effects, whereas highest AT and lowest RH were always found in pavement type. Correlations between landscape metrics and daily AT and RH varied by season. Metrics reflecting the dominance and distribution of underlying surface classifications had closer relationships with microclimate level in the micro-scale environment. The proportion and average patch area of underlying surface classifications were the critical pattern characteristics affecting the daily AT and RH. And the fragmentation and aggregation also had certain influence.
Conclusion When designing micro-scale thermal comfort outdoor space, increasing the proportion and patch area of high and moderate canopy-density vegetation, controlling the fragmentation and adopting aggregating layout can significantly reduce AT and increase RH. The impervious pavement with high proportion, large area and concentrated distribution should be avoided to reduce its thermal regulation negative effect.