Measuring the cooling effects of green cover on urban heat island effects using Landsat satellite imagery
Na Ni, Dan Lou, Dandan Xu, Xuhui Ni, Yanqing Liu, Haobin Wang
Abstract
Rapid urbanization has resulted in urban heat island (UHI) effects becoming a global environmental issue. Urban green space (UGS) can effectively alleviate UHI effects; however, how their spatial arrangements and the cooling radiation region effects on UGS are relatively poorly understood. To advance our understanding, we analyzed Landsat imagery from 2010 to 2021 for the world’s first fine classification product of surface cover to quantitatively analyze the cooling radiation range of UGS. We used buffer analysis to measure the impact of the spatial distribution of UGS on UHI effects from normalized difference vegetation index (NDVI) and variance mean ratio (VMR). UGS has its greatest cooling effect in summer, among which evergreen coniferous forests contribute the most to cooling and grasslands contribute the least. The cooling radiation range of UGS on UHI effects is 300 m, and the cooling effect is most effective from 0 to 200 m. The more the UGS is dispersed, the more significant the cooling effect of UGS. Our study demonstrates that the cooling mechanism of UGS on UHI includes radiation range, types and spatial distribution of UGS, and the approach provides a basis for evaluating UHI effects for urban planning.