Graphical Abstract
Fujita, M., T. Sato, T. J. Yamada, S. Kawazoe, M. Nakano, and K. Ito, 2019: Analyses of extreme precipitation associated with the Kinugawa River flood in September 2015 using a large ensemble downscaling experiment. J. Meteor. Soc. Japan, 97, 387-401.
Special Edition on Tropical Cyclones in 2015–2016
https://doi.org/10.2151/jmsj.2019-022
Graphical Abstract with highlights
Plain Language Summary: We investigated extremely heavy precipitation that occurred around the Kinugawa River, Japan, in September 2015, and the probability of extreme precipitation occurrence, using data from a large ensemble forecast of more than 1,000 members that were dynamically downscaled to 1.6 km horizontal grid spacing. This extreme precipitation event occurred under specific conditions: two coexisting typhoons at close proximity that produced a high atmospheric instability, and water vapor transported from the Pacific Ocean.
Highlights:
- The observed event was statistically rare among simulated cases and the 3-day accumulated precipitation around Nikko was equivalent to the 95th percentile among all simulated ensemble members (1029 members).
- This extreme precipitation event occurred under specific conditions: two coexisting typhoons at close proximity that produced a high atmospheric instability, and water vapor transported from the Pacific Ocean.
- The large-ensemble downscaled data used hence enabled us to evaluate the occurrence probability of a torrential rainfall event that was rarely observed, which may contribute to updating a disaster-mitigating plan for possible similar disasters in future.