Assessing the Cooling Effect of Four Urban Parks of Different Sizes in a Temperate Continental Climate Zone: Wroclaw (Poland)

Urban parks have been known to form park cooling islands (PCI), which can effectively alleviate the effect of urban heat islands (UHI) in cities. This paper presents results obtained for four different size parks in the city of Wroclaw, which is located in a temperate continental climate. The number of publications for urban areas located in this type of climate and cities is low compared to sites in hot and humid areas. Land surface temperature (LST) maps were developed from Landsat 8 Thermal Infrared Sensor (TIRS) data acquired during three hottest weather periods between 2017 and 2019. Metrics and spatial statistics characterising the four parks selected for the analysis based on their size were calculated. These included: perimeter, area, landscape shape index (LSI) and P-LC (forest area) park metrics, and Park Cooling Area (PCA), Park Cooling Efficiency (PCE), Park Cooling Gradient (PCG), Park Cooling Island (PCI) and Extended Park Cooling Island (PCIe) spatial indexes. The averaged PCIe values ranged from 2.0 to 3.6 degrees C, PCI from 1.9 to 3.6 degrees C, PCG from 0.7 to 2.2 degrees C, PCE from 5.3 to 11.5, and PCA from 78.8 to 691.8 ha depending on the park. The cooling distance varied from 110 m to 925 m depending on park size, forest area and land use type in the park's vicinity. The study provides new insight into urban park cooling effects in a medium sized city located in a temperate continental climate, and the role of parks in regulation of urban temperature to mitigate the UHI effect.