Analysis of cold island effect in city parks from the perspectives of maximum and cumulative values – a case study of Xi'an City

The continuous process of urbanization and climate change has led to severe urban heat island (UHI) effects. Constructing parks with cooling capabilities is considered an effective measure to alleviate UHI effects. However, most studies only quantify the cooling effect from a maximum value perspective, lacking a measure of temperature diffusion in space. This study combines the perspectives of maximum value and accumulation to define a cold island index, quantifying the cooling effect of 40 urban parks in the main urban area of Xi'an city. The results show that, on average, urban parks can reduce the surrounding environment by approximately 2.3℃, with a cooling range of about 127.1ha, which is three times the park area. Different factors drive the measurement of the cooling effect using different cold island indexes, but all indexes are highly correlated with green space area. There are significant differences in the cooling effect among different types of parks, and overall, ecological parks have the best cooling effect. The directional spread of internal cold islands in parks is most related to park shape, while external spread is related to surrounding green spaces. The research results have practical value in the construction of parks with cooling effects and the sustainable development of cities in urban planning processes..