An Approach to Characterizing the Spatial Pattern and Scale of Regional Heat Islands Over Urban Agglomerations

Abstract

Great difficulty in characterizing the spatial pattern and scale of regional surface urban heat islands (RSUHIs) over urban agglomerations is mainly attributed to the RSUHI extent exceeding urban boundaries and strong variations in the background climate state and land cover. A new method that successfully addresses these problems by applying the spatial similarity of the land surface temperature (LST) annual cycle in urban agglomerations is proposed to characterize the RSUHI spatial pattern and scale in the Yangtze River Delta of China. This method has good adaptability to complex terrain and climate variations and simultaneously identifies the RSUHI spatial pattern and scale. The RSUHI spatial extent averaged 3.7 × 104 km2 in 2003–2020, which is 1.5–2.0 times the urban extent, and had a fluctuating but increasing tendency. Rapid urbanization and the spatial pattern-shifting LST anomalies were mainly responsible for the fluctuating RSUHI extent during 2003–2020.