Spatial patterns and temporal variations of footprint and intensity of surface urban heat island in 141 China cities

Abstract

l We investigated the spatial patterns and temporal variations of footprint (FP) and intensity of surface urban heat island (SUHI) in 141 China cities. l With the increase of city size, FP showed an increasing trend in medium and small cities, but plateaued in big cities. l SUHI intensity presented spatial and seasonal variations in daytime and nighttime across cities in different climatic zones. l This study is of great help for developing mitigating strategies of SUHI effect in cities with different urbanized levels or climatic background. An improved understanding of urban heat island (UHI) is important in urban ecological and environmental studies. In this study, we investigated footprint (FP) and intensity of surface UHI (SUHI) from 2003 to 2020 in 141 China cities using a Gaussian model and multi-source remote sensing data. Results showed that annual daytime FP in 79% cities was larger than nighttime FP. There were more cities having larger daytime FP than nighttime FP in summer compared to other seasons. With the increase of city size, FP showed an increasing tendency in median or small cities, while plateaued in large cities. We also found that high SUHI intensity occurred in cities with warm climate in daytime but occurred in cities with cold climate in nighttime. Moreover, SUHI intensity in daytime was higher than that of nighttime in all climatic zones in summer, while in other seasons, SUHI intensity in daytime was higher than that of nighttime only in warm climatic zones. Finally, 96% cities showed higher SUHI intensity in daytime than that of nighttime in summer, while proportion of such cities was only 45% in winter. Findings of this study are helpful for mitigating UHI effect in cities with different urbanized levels or climatic background.