## 2 Methods and Materials  
### Methodology  
#### 2.1.1 Study Area and Analysis Targets  
Because this study was performed to analyze HICS effectiveness via actual measurements, it focused on an area in which HICS had been applied. The study area was located in Jangyu Mugye-dong, Gimhae-si, Gyeongsangnam-do, where the Ministry of Environment of the Republic of Korea has implemented a project to prevent heatwaves as a climate change adaptation measure [37]. Trees and vegetation, green roofs, cool pavements, and cool roofs have been established in the region as HICS. Therefore, our selected study area was within a region in which HICS had been applied to a downtown urban area. The HICSs in the study area are set as the analysis targets for this study. The average annual air temperature is 15.1 \({}^{\circ}\)C, and the average temperature in summer is 25.3 \({}^{\circ}\)C. The average annual relative humidity is 62.1%, and the average humidity in the summer is 80.3%. There are 2462.9 h of sunshine per year and 574.5 h in the summer. As of 2022, the average number of clear days per year is 197, and 24 clear days were recorded during the period from June to August, which corresponds to summer ([[https://data.kma.go.kr](https://data.kma.go.kr)]([https://data.kma.go.kr](https://data.kma.go.kr)) (accessed on 31 August 2023)). The total size of the study area was approximately 0.185 km\({}^{2}\) (Figure 2).  
Figure 1: Study workflow.  
HICS effectiveness, in this study, was estimated based on differences in average LSTs between the experimental and control groups. The experimental groups in this study included zones where one of three cooling mechanisms was utilized in HICS. First, they included zones where evapotranspiration occurs from the surfaces of trees, vegetation, and green roofs [3, 6]. Zones where the cooling effect was exerted by evapotranspiration were defined as UGSs. Second, they included zones where overheating was suppressed by the high-albedo materials of cool pavements and roofs, corresponding to GBAM [7, 8, 9]. Zones where the cooling effect was exerted by high-albedo materials were defined as GBAM zones. Third, they included zones that experienced a cooling effect from the shadows formed by trees and vegetation, as well as green roofs, in UGSs [10, 11]. The shaded areas formed by plants were defined as shadow zones in UGSs. Therefore, UGSs, GBAM zones, and shadow zones in UGSs were regarded as the experimental groups in this study (Table 1).  
Figure 2: Study area and heat island cooling strategies (HICS): (**a**) vegetation and trees, (**b**) cool pavement, (**c**) green roof, (**d**) shadow zone provided by shrubs, (**e**) cool roof, and (**f**) shadow zone provided by trees.  
The control groups were zones that were unaffected by HICS. The UGSs and GBAM zones generated a cooling effect by modifying the physical properties of artificial cladding surfaces, which contribute to elevated urban temperatures. Therefore, zones with general artificial cladding that lacked cooling measures were regarded as control groups for the UGSs and GBAM zones; they were referred to as \"built-up zones.\" The control groups for shadow zones in UGSs where the LST is reduced by blocking solar radiation were regarded as unshaded zones in the study area. They had the opposite LST characteristics and were referred to as \"unshaded zones\" (Table 1).