## 4 Discussion  
This study explored the extent to which HICS effectiveness is influenced by various temporal and spatial conditions. Here, temporal conditions refer to different TPs during the daytime and the relative influence of solar radiation according to cloudiness conditions. For spatial conditions, the analysis targets were classified according to SVF to determine changes in cooling effect depending on SD. Under these conditions, this study analyzed the following: first, differences in HICS effectiveness for each level of SD based on the same TPs; second, the range of variation in cooling effects of HICS for each level of SD during the daytime; and third, differences in cooling effects between morning and afternoon TPs for each level of SD. The cooling effects of UGSs were determined as follows. First, analysis of the cooling effects of UGSs by SD at the same TP revealed that cooling effects increased as the SVF approached 1.0, corresponding to a low-SD environment (Table 4). Assessment of meteorological differences showed that cooling effects were stronger when the weather was affected by solar radiation. Cooling effects in the SVF range of 0.0-0.2 were \(-\)0.936 to \(-\)0.312 \({}^{\circ}\)C (less affected by solar radiation) and \(-\)1.678 to \(-\)0.025 \({}^{\circ}\)C (affected by solar radiation), with differences of < 1 \({}^{\circ}\)C. Cooling effects in the SVF range of 0.8-1.0 were \(-\)9.749 to \(-\)3.833 \({}^{\circ}\)C (less affected by solar radiation) and \(-\)13.704 to \(-\)3.887 \({}^{\circ}\)C (affected by solar radiation); the affected by solar radiation conditions produced a cooling effect that was approximately 4 \({}^{\circ}\)C larger than the effect of the less affected by solar radiation conditions. This analysis revealed that strong cooling effects of UGSs can be expected in a low-SD environment when meteorological conditions are affected by solar radiation. Second, analysis of the daily variation in cooling effects of UGSs for each level of SD demonstrated that diurnal variation in the cooling effect increased as the SVF approached 1.0 (Table 4). When meteorological conditions were affected by solar radiation, there was greater diurnal variation in the cooling effect. In the SVF range of 0.0-0.2, which corresponded to a high-SD environment, the diurnal variations in cooling effect were \(-\)0.624 \({}^{\circ}\)C (less affected by solar radiation) and \(-\)1.653 \({}^{\circ}\)C (affected by solar radiation). In the SVF range of 0.8-1.0, corresponding to a low-SD environment, the diurnal variations in cooling effects were \(-\)5.916 \({}^{\circ}\)C (less affected by solar radiation) and \(-\)9.817 \({}^{\circ}\)C (affected by solar radiation). This analysis revealed that diurnal variation in cooling effects was high when meteorological conditions were affected by solar radiation with a low SD. Third, analysis of the difference in cooling effects of UGSs between morning and afternoon indicated similar cooling effects, regardless of SD, when meteorological conditions were less affected by solar radiation. However, when meteorological conditions were affected by solar radiation, the cooling effect was greater in the morning than in the afternoon as the SD increased (Table 4). When meteorological conditions were less affected by solar radiation, the cooling effect was greater in the morning (\(-\)0.469 \({}^{\circ}\)C) and afternoon (\(-\)1.033 \({}^{\circ}\)C) under high-SD conditions. When meteorological conditions were affected by solar radiation, the cooling effects were 0.307 \({}^{\circ}\)C in the SVF ranged from 0.0-0.2 and \(-\)6.716 \({}^{\circ}\)C in the SVF range of 0.8-1.0; the cooling effect tended to be larger in the morning than in the afternoon because morning conditions more closely resembled a low-SD environment (Table 4). The difference in cooling effect between morning and afternoon was greater in a low-SD environment; it was largest when meteorological conditions were affected by solar radiation. The cooling effects of GBAM zones were characterized as follows.