Date of Award
Doctor of Philosophy (PhD)
Typhoons are among the most common and dangerous natural hazards that affect the coastal regions and islands in Asia. The typhoon activity is expected to increase in the future due to climate change. In this study, a stochastic typhoon simulation framework has been developed to simulate the typhoon tracks. An improved typhoon track simulation model is implemented which can be used to generate long-term typhoon database for Asia consisting of typhoon tracks with parameters including latitude, longitude, translational speed, heading direction, central pressure, radius of maximum winds and Holland B parameter simulated at 6h time interval. A new regression equation is introduced for modeling the radius of maximum winds (RMW) and Holland B parameter. Central pressure decay model is developed individually for mainland Asia, Japan, Philippines and Taiwan. The simulation model is used to generate long-term typhoon track database for Asia. The track database is validated by comparing the statistics of various typhoon parameters of the simulation model with past typhoon historical records. Typhoon database generated using the simulation model is validated with historical typhoon records by comparing the key parameters of simulated storms with historical observations at selected locations in the coast of China, Japan, Philippines, Taiwan and Korea. Good agreement is observed between simulated and historical tracks. The track database is used to produce a long-term typhoon wind-hazard database which can be used to generate wind hazard curves. The wind speeds calculated are validated using historical wind speed data provided by wind stations from various sources. The wind database is developed for coastal regions of Japan, China, Vietnam, Philippines and Taiwan and the database can be used for estimating the wind speeds at several return periods, allocating wind loads in design of structures and also assessing the insurance loss to prepare the funds required to mitigate the typhoon wind damage in coastal areas.
Impact of global warming on typhoon activity is analyzed in this study. Sea surface temperature is one of the major factors in intensifying the storms. Sea surface temperature projections under multiple climate change scenarios based on global climate models (GCM) in The United Nations Inter Governmental Panel (IPCC) 5th assessment report are considered in this study. The sea surface temperature projection by three Representative Concentrated Pathways (RCP) of greenhouse gas emissions by the end of this century are incorporated in the typhoon simulation model. Scientific observations show latitude band of tropical cyclones is likely to shift poleward due to global warming. Sea surface temperature and poleward shift of storm genesis are two scenarios of climate change analyzed in this study. Twelve different climate change scenarios which consider the effect of poleward shift and RCPs are analyzed to understand the impact of these scenarios on typhoon activity in Asia. Typhoon databases are generated using the twelve climate change scenarios in 2100 and compared with the typhoon activity under current climate. Changes in annual approach rates of typhoons under multiple climate change scenarios are calculated. Wind speeds are calculated using each climate change scenario for multiple locations in the coast of Asia. Changes in the wind speeds for different return periods are analyzed for each climate change scenario by comparing with windspeeds of current climate condition. To investigate the influence of environmental variables on genesis activity, a genesis index regression equation is considered with sea surface temperature, relative humidity, wind shear and absolute vorticity as variables. Coefficients are fitted for environmental variables to estimate storm genesis rate. Environmental variables from RCP2.6, RCP4.5 and RCP8.5 in year 2100 are substituted in the genesis index equation to estimate the change in storm frequency under three RCP scenarios. Track databases are generated using the genesis index and sea surface temperatures of three RCP scenarios. Wind speeds are calculated for selected locations in the coast of Asia to estimate the impact of climate change in occurence rate and wind hazard in these locations.
Polamuri, Sri Harshitha, "Projections of Typhoon Wind Speeds for Estimating the Future Typhoon Wind Hazard Due to Climate Change in the Asia Pacific Basin" (2019). All Dissertations. 2530.