Spatiotemporal patterns of the impact of surface roughness and morphology on urban heat island

As important determinants of urban thermal environment, surface roughness and morphology have been extensively studied for sustainable urban development. In this study, we quantify the effect of urban roughness and morphology on the surface urban heat island (SUHI) intensity and its spatiotemporal patterns, over seventeen major cities in six urban agglomerations of China. We employ multisource dataset and derive multiple measures, representative of the roughness and horizontal/vertical indicators of urban morphology. The results show that the correlation between the SUHI intensity and urban morphological indices is significantly strengthened with the heat island intensity, manifested by the contrasting Pearson's r in summer (r = 0.59 +/- 0.13) and winter (0.11 +/- 0.35). In general, the impact assessed using different measures of surface morphology is consistent on the SUHI intensity, while the one-dimensional (1D) roughness emerges as an adequate index not inferior to more complex morphological parameters. Our study also shows that the impact of urban morphology varies in different geographic and climatic regions, as well as with different urban management, which highlights the importance of locality and site-specific design in implementing effective urban heat mitigation strategies.