Multiscale synergistic effects of urban green space morphology on heat-pollution: A case study of Guangdong-Hong Kong-Macao Greater Bay Area, China

Abstract

Urban heat island and air pollution issues caused by ozone (O₃) and particulate matter (PM_2.5) pose serious threats to the public health. The synergistic impact of urban green space (UGS) on both seasonal heat and air pollution (heat-pollution) from a multiscale perspective remains a scientific challenge. Land surface temperature (LST), O₃ and PM_2.5 were used as research variables. Morphological Spatial Pattern Analysis (MSPA) was applied to quantify urban green space morphology (UGSM), and the PLUS model was employed to explore the future spatial patterns of UGS under three scenarios. A multiscale perspective combined with multiscale Geographically Weighted Regression (MGWR) and SHapley Additive exPlanations (SHAP) was used to reveal the complex impacts of UGSM on heat-pollution. The results showed that from 2000 to 2020, the area and aggregation degree in the study area decreased. High values of LST, O₃ and PM_2.5 concentrations were primarily distributed in main urban expansion zones. The impact of UGSM on LST, O₃ and PM_2.5 exhibited spatial heterogeneity and scale effect, and the degree of impact increased with scale. Moreover, the overall contribution of UGSM indicators to LST, O₃ and PM_2.5 varied at different scales. On the whole, UGSM effectively mitigate LST. Seasonal analysis reveals that UGSs most significantly regulate LST in summer. UGSM indicators also exhibit seasonal variability in their effects on O₃ and PM_2.5. UGSM optimization strategies targeting to heat-pollution were proposed. This study provides recommendations for improving UGS planning and mitigating the heat-pollution problem in the Greater Bay Area.