# Recent Spatiotemporal Changes of Subhourly Extreme Rainfall Events in Seoul
## 4 Results
### Spatial Pattern Changes in Extreme Rainfall Events  
To examine the alterations in the spatial distribution of AMP across Seoul, the CVs for the AMP series over selected durations were computed and are depicted in Figure 5. CVs were calculated from the AMP of different stations in the same year. Thus, CVs may be able to indirectly represent the spatial distribution or dispersion of AMPs. This figure reveals that the changes in the CV series for AMP varied depending on the duration considered. For the 15 min duration, the CV series showed a decreasing trend. In contrast, increasing trends were observed for durations of 30, 45, 60, 120, 180, and 240 min, with the 45 min and 60 min durations showing statistically significant trends. Meanwhile, for the 300 min and 360 min durations, the slope estimates were nearly zero, indicating no discernable trends in the CV series for these durations. These findings highlight significant changes in the spatial patterns of extreme rainfall events in Seoul, particularly for subhourly durations. Figure 4: Time series of annual maximum precipitation (AMP) mean for each year at various durations: (**a**) 15 min, (**b**) 30 min, (**c**) 45 min, (**d**) 60 min, (**e**) 120 min, (**f**) 180 min, (**g**) 240 min, (**h**) 300 min, and (**i**) 360 min. The blue linear lines indicate statistically significant increasing and decreasing trends, respectively, detected at the 10% significance level. The black dashed line means linear regression line without statistically significant trend. Additionally, ** and * indicate statistically significant trends at the 5% and 10% significance levels, respectively. Figure 5: _Cont._To comprehensively analyze the changes in the spatial distribution of extreme rainfall, the [PERSON]'s \(I\) time series for AMP was calculated for each duration; these are presented in Figure 6. The findings of the [PERSON]'s \(I\) series aligned with the results of the CV series presented in Figure 5 but were not exactly the same. For all durations considered, the [PERSON]'s \(I\) series exhibited increasing trends. Specifically, these trends were statistically significant at the 5% significance level for the 30 min, 45 min, 60 min, and 120 min durations and at the 10% significance level for the 180 min duration. A high [PERSON]'s \(I\) value reflects strong spatial autocorrelation, indicating that the AMP recorded at different rainfall gauge stations within a given spatial domain occurs under the same rainfall event. As the duration increased, the likelihood of AMP occurring because of rainfall from larger systems, such as typhoons and monsoons, also rose. Consequently, the value of [PERSON]'s \(I\) increased with longer durations, and the probability of statistically significant autocorrelations rose. This trend was evident in the growing number of years with statistically significant [PERSON]'s \(I\) values as the duration lengthened. As shown in Figure 6b, [PERSON]'s \(I\) values were not  
Figure 5: Time series of coefficients of variation (CVs) for annual maximum precipitation at various durations: (**a**) 15 min, (**b**) 30 min, (**c**) 45 min, (**d**) 60 min, (**e**) 120 min, (**f**) 180 min, (**g**) 240 min, (**h**) 300 min, and (**i**) 360 min. The red linear lines indicate statistically significant increasing and decreasing trends, respectively, detected at the 10% significance level. The black dashed line means linear regression line without statistically significant trend. Additionally, ** and * indicate statistically significant trends at the 5% and 10% significance levels, respectively. statistically significant before 2011, but significant autocorrelations were detected in six subsequent years. Similar patterns are evident in Figure 6c,d, particularly in AMP for subhourly durations. Figure 6: Time series of [PERSON]’s \(I\) index from annual maximum precipitation in Seoul for various durations: (**a**) 15 min, (**b**) 30 min, (**c**) 45 min, (**d**) 60 min, (**e**) 120 min, (**f**) 180 min, (**g**) 240 min, (**h**) 300 min, and (**i**) 360 min.