Cooling effects of wetland parks in hot and humid areas based on remote sensing images and local climate zone scheme

Wetland parks, as essential components of urban blue and green landscapes, have long been proven to provide cooling benefits to high-temperature urban spaces. This study aims to clarify the comprehensive cooling effects of wetland parks on the surrounding built-up areas. Ten typical wetland parks in Guangzhou, China, were selected as the research objects, and the local climate zone (LCZ) around these parks was divided considering a radius of 600 m. Land surface temperature (LST) distribution transitions from winter to summer were obtained for a six-month period using a mono-window algorithm retrieved from remote sensing image data from Landsat 8. Cooling factors of wetland park morphological indices and LCZ indicators were calculated using buffer zone analysis and treated as independent variables. Cooling effect indicators, namely cooling distance (PCD), cooling range (PCR) and cooling gradient (PCG), were considered as dependent variables. A quantitative correlation factor analysis was performed to examine the relationship between these variables. The results showed that these factors have varying degrees of influence on the cooling indices. Among them, LCZ characteristic factors, including sky view factor (SVF), permeable surface fraction (PSF), and aspect ratio (AR), have a greater influence on the cooling effects than the wetland park's own characteristics. Based on these results, we attempted to determine quantitative equations illustrating the relationships between the cooling effect indices and the influencing factors to provide theoretical guidance for climate-sensitive urban design near wetland parks.