Future changes in typhoons and storm surges along the Pacific coast in Japan: proposal of an empirical pseudo-global-warming downscaling

In this study, dynamical pseudo-global-warming downscaling (d-PGWD) was performed with a high-resolution typhoon model for 49 typhoons that made landfall in Japan between 2000 and 2017. It was revealed that the averaged typhoon intensity under future climatic conditions tends to increase at both the peak and landfall times as a result of global warming (averaged central pressures of -45.7 and -5.5 hPa at peak and landfall, respectively). Furthermore, detailed analyses of the time of landfall revealed significant differences in the degree of future changes in typhoon intensity based on both the elapsed time from the genesis to landfall (T-l) and the radius of maximum wind speed (R-ml) at the time of landfall. Considering the relationships of T-l and R-ml between present and future climates, statistical formulas for future changes in the central pressure and R-ml were derived as an empirical PGWD (e-PGWD) method. The validity of this method was confirmed via comparison with d-PGWD results. It is expected that disaster prevention and mitigation measures for future typhoons and coastal disasters in individual regions and ports can be developed by revising storm surge hazard maps using the proposed e-PGWD approach.

Automated summary

In this study, the authors used a high-resolution typhoon model to simulate and analyze 49 typhoons that made landfall in Japan between 2000 and 2017. The study revealed an increasing trend in typhoon intensity under future climatic conditions, both at peak and landfall times. Furthermore, the degree of change in typhoon intensity was found to be influenced by the elapsed time from genesis to landfall and the radius of maximum wind speed at landfall. By establishing statistical formulas, future changes in central pressure and radius of maximum wind speed can be predicted, providing guidance for disaster prevention and mitigation measures in coastal regions and ports.