Assessment of daytime and nighttime surface urban heat islands across local climate zones – A case study in Florianópolis, Brazil

Abstract

Affected air movement, artificial heat production, increased solar absorption and suppressed vegetation cause significant temperature differences between urban and suburban/rural regions, forming Surface Urban Heat Islands (SUHI). Here, we propose a methodological framework combining daytime and nighttime Landsat 8 data with comprehensive statistical evaluation based on the retrieved information. To quantify SUHI, we selected a pair of daytime and nighttime Landsat 8 scenes, calculated the Urban Thermal Field Variance Index and applied a comprehensive statistical approach to assess differences in SUHI behaviour across Local Climate Zones and between day and night, examining its relationships with albedo, elevation, land surface emissivity and vegetation cover. Open urban typologies were characterised by milder day temperatures, especially over open areas with higher buildings, while compact low-rise areas presented the highest SUHI intensity. Higher buildings presented more intense SUHI at night, with milder temperatures over open and low-rise regions. These results confirm the SUHI dynamics and its strong association with the urban structure and the presence of vegetation. The proposed complex methodological framework can be, with minor adjustments, applied to other regions as well, which can improve the comparability among studies on SUHI and promote our understanding of its causes and possible mitigation measures.