Suburban greening and suburbanization changing surface urban heat island intensity in China

There is no clear evidence to date whether suburban greening and suburbanization affect the surface urban heat islands intensity (SUHII). Based on the accurate identification of suburban areas, this study examined the spatiotemporal trends of SUHII in experimental subjects from 201 prefecture-level cities in China. Then, suburban greening and suburbanization were examined for their effects on SHUII. Results showed that the SUHII trend in Chinese cities is generally increasing both annually and seasonally (except in winter). Among cities with suburban greening, especially large and medium-sized cities, 53.7% and 68.7% increased their SUHII annually during daytime and nighttime, respectively. In cities with decreasing levels of suburbanization, especially megacities, the annual SUHII at daytime and nighttime increased significantly by 51.7% and 56.7%, respectively. Sensitivity tests indicated the findings were robust during the daytime, whereas the relationship between suburban greening and SUHII at nighttime was sensitive to the suburban extent. Our study suggests that strengthening urban greening and improving suburbanization levels are important to reduce the urban heat island in cases of suburban greening and suburbanization decreasing.