Summary/Abstract
Recent observational and modeling studies highlight the growing global impacts of heavy precipitation. Although daily extremes have been widely studied, short-duration precipitation events that often result in pluvial floods have received less attention. This study analyzes historical changes in hourly precipitation across Japan using observational data and large ensemble simulations with a 20-km resolution. The findings indicate that human activities have increased the likelihood of hourly precipitation exceeding 30 mm/h. Since the 1980s, the influence of anthropogenic factors has grown more pronounced on hourly extremes than on daily events, suggesting that short-term precipitation is more sensitive to global warming. In addition, the area prone to heavy precipitation has expanded northward with each passing decade. These results imply that cumulative anthropogenic influences and associated temperature rise have increasingly altered thermodynamic atmospheric environments conducive to convective precipitation. These results highlight the importance of strengthening disaster preparedness in regions that were previously unexposed to short-term heavy precipitation. Because simulated precipitation relies on a cumulus parameterization scheme, further quantitative assessment using cloud-resolving models is warranted.