Investigating the micro-scale thermal effects of natural underlying surfaces on adjacent spaces in a subtropical zone with an optimized method

Abstract

Micro-scale thermal interactions between underlying surfaces and their surrounding air in urban spaces critically influence urban residents' thermal comfort. On the micro-scale, heat can induce substantial changes in the air temperature (Ta) at the pedestrian height. To characterize the spatiotemporal distribution of the Ta for spaces adjacent to the underlying surfaces, an accurate measurement method is essential. This study explored the proper spatial interpolation methods (SIMs) through strategically-arranged measurement points and then assessed the spatiotemporal distribution of Ta in a tiny experimental area. Results showed that the selection of SIMs and interpolation points significantly affected the results for the micro-scale spatial interpolation. The Ta might fluctuate precipitously within extremely short distances between adjacent underlying surfaces, depending on their thermal properties or on the locations of shadows. At the pedestrian height, the Ta readings registered a maximum difference of 1.31 °C for the same areas with and without arbor shading. However, the arbors' cooling extent and location depended on their shading's position, which constantly changed during the day. The shrubs and the lawn under direct sunlight hardly regulated the microclimate, even in the periphery. Additionally, solar radiation and wind speeds influenced the Ta spatial distribution on the micro-scale. Therefore, future micro-scale urban designs should take into consideration the dynamic positioning of arbor shading, given its significant cooling effect.