Impact of synoptic condition on urban microclimate variation: A measurement study in a humid subtropical city during summer season

The urban microclimate is not only predominated by synoptic weather features but also closely related to heterogeneous characteristics of urban morphology. This study conducted an on-site field measurement campaign in Guangzhou, China from July to August 2021 to investigate the urban microclimate variation under typical synoptic conditions according to the Spatial Synoptic Classification (SSC) scheme. The climatic data were collected from eight locations installed in three residential neighborhoods. Cooperating with the statistical test, the results of deviation analysis demonstrate inconsistent urban microclimate variations among different SSC weather types. Under the moist moderate and moist tropical synoptic conditions, the urban microclimate variations between locations are insignificant. According to the results of the correlation analysis, the associations between morphological factors relating to building density and thermal environment are negative at noon but positive in the afternoon and night. The highest correlation coefficient is found between the ground coverage ratio and mean radiant temperature during nighttime under the extreme moist tropical weather types (0.58), but it turns out to be 0.29 at noon. These findings suggest that the application of the SSC benefits understanding reasons for microclimate variation within urban areas and detecting critical urban morphological indicators for achieving better thermal environments.