1:45 PM - 2:00 PM
[AAS06-01] Study for the creation of stochastic typhoon events in future climate
There is concern that climate change may lead to more severe typhoon disasters. Ministry of the Environment (2023)*1 conducted simulations about the impact of similar typhoons under global warming conditions for Typhoon Hagibis and Jebi. Simulation results indicated that both cases increased the risk of river flooding, wind damage, and storm surge.
Severe natural disasters are one of the factors that cause casualty insurance companies to increase insurance claim payments. If typhoon disasters tend to become more severe due to climate change, insurance claims payments are expected to increase in the future. Risk management based on quantitative assessment is required to provide insurance services sustainably.
One of the methods to quantitatively visualize the risk and uncertainty of wind disasters among typhoon disasters is using a risk assessment model (Catastrophe model; CAT model) with the stochastic typhoon event set. The stochastic typhoon event set collects many hypothetical events that are statistically modeled based on past observation data and randomly simulated on a computer. It is possible to assess wind disaster risk quantitatively using this event set.
Stochastic typhoon event sets are usually created for the present climate, and few cases are created for future climate (e.g., Umeda et al. (2019)*2). In this study, we extracted typhoons from the database for Policy Decision making for Future climate change (d4PDF) and surveyed differences between present and future climate (+2°C and +4°C scenario). Instead of using the published TC (Tropical Cyclone) track data based on d4PDF, we extracted TC tracks from d4PDF by ourselves because the methodologies for TC extraction should be the same as the existing stochastic typhoon event set. Also, we have created future TC track data corresponding to +2°C scenario, which is not included in the published dataset.
In the future climate, the number of typhoon events will decrease. However, the main occurrence area of typhoons tends to shift northward. Furthermore, cluster analysis for typhoon tracks in the future climate reveals that the number of typhoons moving westward through the Philippine Sea tends to decrease compared to the present climate. On the other hand, the number of typhoons moving northward over the southeastern part of Japan’s offshore tend to increase. We attempt to create stochastic typhoon events in the future climate based on the results of these analyses.
*1: Ministry of the Environment: Typhoons are increasing in strength - What risks are we facing? -2023, 2023. (In Japanese)
*2: Umeda, J., Nakajo, S., and Mori, M.; Development of Global Stochastic Tropical Cyclone Model by using large ensemble GCM simulation data(d4PDF), J.JSCE, Ser.B2, Coastal Engineering, Vol. 75, No. 2, pp. I_1195-I_1200, 2019. (In Japanese)
Severe natural disasters are one of the factors that cause casualty insurance companies to increase insurance claim payments. If typhoon disasters tend to become more severe due to climate change, insurance claims payments are expected to increase in the future. Risk management based on quantitative assessment is required to provide insurance services sustainably.
One of the methods to quantitatively visualize the risk and uncertainty of wind disasters among typhoon disasters is using a risk assessment model (Catastrophe model; CAT model) with the stochastic typhoon event set. The stochastic typhoon event set collects many hypothetical events that are statistically modeled based on past observation data and randomly simulated on a computer. It is possible to assess wind disaster risk quantitatively using this event set.
Stochastic typhoon event sets are usually created for the present climate, and few cases are created for future climate (e.g., Umeda et al. (2019)*2). In this study, we extracted typhoons from the database for Policy Decision making for Future climate change (d4PDF) and surveyed differences between present and future climate (+2°C and +4°C scenario). Instead of using the published TC (Tropical Cyclone) track data based on d4PDF, we extracted TC tracks from d4PDF by ourselves because the methodologies for TC extraction should be the same as the existing stochastic typhoon event set. Also, we have created future TC track data corresponding to +2°C scenario, which is not included in the published dataset.
In the future climate, the number of typhoon events will decrease. However, the main occurrence area of typhoons tends to shift northward. Furthermore, cluster analysis for typhoon tracks in the future climate reveals that the number of typhoons moving westward through the Philippine Sea tends to decrease compared to the present climate. On the other hand, the number of typhoons moving northward over the southeastern part of Japan’s offshore tend to increase. We attempt to create stochastic typhoon events in the future climate based on the results of these analyses.
*1: Ministry of the Environment: Typhoons are increasing in strength - What risks are we facing? -2023, 2023. (In Japanese)
*2: Umeda, J., Nakajo, S., and Mori, M.; Development of Global Stochastic Tropical Cyclone Model by using large ensemble GCM simulation data(d4PDF), J.JSCE, Ser.B2, Coastal Engineering, Vol. 75, No. 2, pp. I_1195-I_1200, 2019. (In Japanese)