Effects of urban form on sea cooling capacity under the heatwave

Abstract

The sea is considered an important factor for ameliorating urban heat island effects in coastal cities, especially during heatwaves. Nevertheless, the mechanisms for urban form factors and sea cooling are poorly understood. To fill this gap, under the heatwave, coastline urban heat island intensity (CUI) was proposed to evaluate the cooling effect of the sea in Dalian (a coastal city in China), and combined with spatial autoregressive models to explore the impact of urban form factors on CUI. Results were as follows: 1) the sea showed the greatest cooling potential within a distance of 2.5 km, with a maximum cooling range of 9.2 km; 2) land cover factors had the strongest influence on CUI; 3) building average height and sky view factor in the offshore area had a prominent influence on CUI than inland; 4) distance to the coastline had obvious effect on CUI. Urban form affects the cooling capacity of the sea by affecting the surface temperature and the fluidity of the wind, which showed spatial heterogeneity. Above all, mitigation strategies were proposed, such as control of the underlying surface material, and the urban form should be dominated by low-density multistory/high-rise in the offshore.