녹지와 비녹지의 도시냉섬효과 비교

Research to reduce urban temperatures and mitigate the Urban Heat Island (UHI) effect has focused primarily on the role of large urban green spaces as cool islands (Oke, 2004;Park et al., 2017). However, the role of small green spaces (SGs) such as street trees and pocket parks has not been fully investigated. The purpose of this research is to assess the mitigating effect of SGs on micro-UHI through a comparative analysis of air temperatures of SGs and non-green spaces (NGs), that include building-shaded spaces (BS) and non-shaded, impervious, paved spaces (PS) completely exposed to sunlight. Six urban blocks were the study site and in a highly developed area, Jongnogu and Junggu, Seoul, 37°34′N 126°58′E, South Korea and also located in the same micro-climatic zone. They had SGs which were vegetation patches presented as distinct areas of tree cover. And they were mapped through aerial images analysis and field survey. The experiment was conducted across six urban blocks in a highly developed area in Seoul, South Korea during daytime in summer. Two researchers at each block simultaneously recorded air temperatures at 1.5 m above the ground level using mobile loggers at one-minute intervals for an hour. Measurements were repeated three times, and 1,296 temperature readings were collected in total and made 174 mean temperature data. ArcGIS was used to perform solar radiation analysis to highlight SGs, BSs, and PSs on a thermal map. The highest air temperatures and the lowest air temperatures of each block were extracted and classified. ANOVA and Kruskal-Wallis H test utilizing SPSS statistics were used to verify the significant differences in mean air temperatures between SGs (TSG), PSs (TPS), and BSs (TBS). As a result, ΔTPS-B (the thermal effect of PSs on a block‘s air temperature) ranged from –1.38 ℃ to 2.28 ℃ with fifty-six points, ΔTBS-B (the thermal effect of BSs on a block’s air temperature) ranged from –2.38 ℃ to 2.38 ℃ with fifty-eight points and ΔTSG-B (the thermal effect of SGs on a block’s air temperature) ranged from –1.98 ℃ to 1.62 ℃ with sixty points. 68% (N = 41) of SGs were a negative number of ΔTSG-B while 50% of BSs shows a negative number. The result means that SGs contribute to reducing microscopic UHI than BSs which have much more shade area than SGs have. The results showed that SGs contributed to significantly reducing TBi up to 2.9 ℃ while BS reduced TBi up to 2.7 ℃. The highest TBi was on a PS. The air temperature difference between SGs and NGs over all the blocks ranged from 0.9 ℃ to 2.9 ℃. The air temperature difference between PS and SG was significant and ranged from 0.2 ℃ to 2.0 ℃, while the difference between BS and SG was significant and ranged from 0.1 ℃ to 1.2 ℃.