| The western North Pacific(WNP)basin is the highest prone area of tropical cyclones(TCs)globally.China,located on the west coast of the WNP,is one of the countries most seriously affected by typhoons in the world.As the strong wind,rainstorm,storm surge,and flood cause serious damage to the typhoon passage areas,it is necessary to quantify the risk of typhoon disasters for wind-resistant design,regional disaster prevention planning,insurance and reinsurance industries.However,when and where typhoons will happen have great uncertainty,and their track,intensity,and coverage cannot be accurately predicted beforehand.Therefore,the typhoon hazards and risk analysis should be based on the probability theory.In addition,more and more studies show that typhoon activities are affected by climate change.How to incorporate the effect of climate change in the typhoon hazard analysis is also an important issue to cope with the global warming.To promote scientific decision-making for wind disaster mitigation,and to enhance the capability of human being to cope with typhoons,the typhoon hazard analysis method is systematically investigated based on the latest developments in atmospheric dynamics,climate change,and hazard analysis theory for natural perils.Thus an atmospherical physics-based synthetic TC model is developed.Furthermore,a typhoon hazard analysis method considering the influence of the global climate warming and the El Ni?o-Southern Oscillation is also developed.It is then applied to the typhoon hazard assessment for the coastal areas of China and East Asia.The researches in this dissertation are expected to provide a theoretical basis and application tool for the disaster-resistant design of major engineering infrastructures,disaster risk management and prevention of the typhoon-affected regions.The main contents are as follows:(1)To model the TCs in the WNP basin where typhoons originate and affect the East Asia coastal areas,a statistical dynamics-full track synthetic TC model is developed based on the relationship between TCs and atmospheric environmental variables.The model inherits the idea of traditional empirical full track model in synthesizing TCs and is improved in the genesis,track,and intensity simulation of TCs.The improvements put the new model on a more solid meteorological basis.Compared with the historical TC events and their statistical characteristics,the results show that the model is adequate to simulate the TC activities in the WNP.(2)The statistical dynamics-full track synthetic TC model is combined with the global climate models to further develop the typhoon hazard analysis method in climate change scenarios.The model is used for simulating the TC activities in the WNP basin under RCP8.5 warming climate.Quantitatively assessments of the impact of warming climate on the genesis,track,and intensity of TCs are made,and it shows that the warming climate will lead to an increase in the number of TCs genesis,and an overall eastward shift of tracks in the WNP basin.This results in an increase of passing rates in the middle of the WNP and a decrease in the southwest part of the WNP.The future frequency of the weaker and moderate typhoons will decrease slightly,while that of the super intense typhoons will increase significantly.(3)A large number of TCs in the WNP basin is simulated by using the method developed in this study to assess the typhoon hazards in the coastal areas of China and East Asia.The TC passing rates and extreme wind speeds in different return periods in 10 major cities along the southeast coast of China are obtained,and the extreme wind speed maps of this area are drawn.Considering the global warming,a quantitative evaluation of the impact of climate warming on the typhoon hazards in East Asia is made by projecting to the last 30 years of this century(2071~2100).It shows that the extreme wind speeds of 50-year and 100-year return periods in the coastal areas of East Asia will increase at the end of this century.The eastern and northern coastal areas of China are the regions most affected by climate warming.(4)The statistical dynamics-full track synthetic model is used to simulate the TC activities in the WNP basin under the three phases of El Ni?o-Southern Oscillation.It is found that the genesis positions and tracks gradually shift to the northwest from El Ni?o year to Neutral year,and further to La Ni?a year.By quantitatively assessing the difference of TC passing rates and extreme wind speeds in the coastal areas of China under the three phases,it shows that the passing rate and extreme wind speed in the La Ni?a year are higher than those in the El Ni?o year.In addition,the disturbance of El Ni?o-Southern Oscillation increases the uncertainty of interannual typhoon hazards,but has little effect on that of multi-decadal typhoon hazards. |
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