Quantifying the cool island intensity of urban parks using ASTER and IKONOS data

Urban parks can help mitigate urban heat island (UHI) effects and decrease cooling energy consumption in summer. However, it is unclear how park characteristics affect the formation of a park cool island (PCI). In this study, PCI intensity values for 92 parks in Nagoya, Japan were obtained from ASTER land surface temperature (LST) products and then correlated to detailed and use information derived from high-spatial-resolution IKONOS satellite data. The results indicate that (1) the cooling effect depends on the park size and seasonal radiation condition, and park size is non-linearly correlated to PCI intensity; (2) PCI intensity is mainly determined by the area of tree and shrub inside the park as well as the park shape, and grass has negative impact on PCI formation. The park vegetation and shape index (PVSI) proposed here well predicted PCI intensity of selected parks. These findings can help urban planners to understand PCI formation and design cool parks to counteract UHI effects.