The effects of wave-induced radiation stress on storm surge were simulated during Typhoon Saomai using a wave-current coupled model based on ROMS （Regional Ocean Modeling System） ocean model and SWAN （Simulating Wa...The effects of wave-induced radiation stress on storm surge were simulated during Typhoon Saomai using a wave-current coupled model based on ROMS （Regional Ocean Modeling System） ocean model and SWAN （Simulating Waves Nearshore） wave model. The results show that radiation stress can cause both set-up and set-down in the storm surge. Wave-induced set-up near the coast can be explained by decreasing significant wave heights as the waves propagate shoreward in an approximately uniform direction; wave-induced set-down far from the coast can be explained by the waves propagating in an approximately uniform direction with increasing significant wave heights. The shoreward radiation stress is the essential reason for the wave-induced set-up along the coast. The occurrence of set-down can be also explained by the divergence of the radiation stress. The maximum wave-induced set-up occurs on the right side of the Typhoon path, whereas the maximum wave induced set-down occurs on the left side.展开更多
Recent studies have shown that surface fluxes and exchange coefficients are particularly important to models attempting to simulate the evolution and maintenance of hurricanes or typhoons.By using an advanced research...Recent studies have shown that surface fluxes and exchange coefficients are particularly important to models attempting to simulate the evolution and maintenance of hurricanes or typhoons.By using an advanced research version of the Weather Research and Forecasting(ARW)modeling system,this work aims to study the impact of modified exchange coefficient on the intensity and structures of typhoon Saomai(2006)over the western North Pacific.Numerical experiments with the modified and unmodified exchange coefficients are used to investigate the intensity and structure of the storm,especially the structures of the boundary layer within the storm.Results show that,compared to the unmodified experiment,the simulated typhoon in the modified experiment has a bigger deepening rate after 30-h and is the same as the observation in the last 12-h.The roughness is leveled off when wind speed is greater than 30 m/s.The momentum exchange coefficient(CD)and enthalpy exchange coefficient(CK)are leveled off too,and CD is decreased more than CK when wind speed is greater than 30 m/s.More sensible heat flux and less latent heat flux are produced.In the lower level,the modified experiment has slightly stronger outflow,stronger vertical gradient of equivalent potential temperature and substantially higher maximum tangential winds than the unmodified experiment has.The modified experiment generates larger wind speed and water vapor tendencies and transports more air of high equivalent potential temperature to the eyewall in the boundary layer.It induces more and strong convection in the eyewall,thereby leading to a stronger storm.展开更多
Northwestern Pacific is the only ocean which has the most typhoon formation. The study of typhoon has far reaching significance today. Typhoon can relieve drought and make temperature drop substantially. Even we were ...Northwestern Pacific is the only ocean which has the most typhoon formation. The study of typhoon has far reaching significance today. Typhoon can relieve drought and make temperature drop substantially. Even we were suffering continuous high temperature in summer, the temperature would decrease immediately accompanied with typhoon. By using MODIS and weather station data to calculate the vegetation index, we analyze the drought characteristics of Shanghai during Saomai period, so that we can show the changes from the two aspects of the vegetation growth and the surface temperature. On the other hand, through the relative humidity data of Typhoon Saomai, we can find that the vegetation index and the relative humidity have been increased significantly. Typhoon rain also has its beneficial agricultural production side. It can lift the drought or ease the drought. It also provides abundant water resources for the growth of crops. In addition, the typhoon for the adjustment of the Earth’s heat, is contributed to maintain heat balance. Therefore, the typhoon to bring the changes in hydrothermal environment on the objective assessment of its impact and timely use of typhoon resources are of great significance.展开更多
Tropical cyclone,a high energy destructive meteorological system with heavy rainfall and gale triggered massive landslides and windstorms,poses a significant threat to coastal areas.In this paper we have developed a T...Tropical cyclone,a high energy destructive meteorological system with heavy rainfall and gale triggered massive landslides and windstorms,poses a significant threat to coastal areas.In this paper we have developed a Tropical Cyclone Potential Impact Index （TCPI） based on the air mass trajectories,disaster information,intensity,duration,and frequency of tropical cyclones.We analyzed the spatial pattern and interannual variation of the TCPI over the period 1949-2009,and taking the Super Typhoon Saomai as an example have examined the relationship between the TCPI and direct economic losses,total rainfall,and maximum wind speed.The results reveal that China＇s TCPI appears to be a weak decreasing trend over the period,which is not significant overall,but significant in some periods.Over the past 20 years,the TCPI decreased in the southern China coastal provinces of Hainan,Guangdong and Guangxi,while it increased in the southeastern coastal provinces of Zhejiang,Fujian and Taiwan.The highest values of TCPI are mainly observed in Taiwan,Hainan,the coastal areas of Guangdong and Fujian and Zhejiang＇s southern coast.The TCPI has a good correlation （P=0.01） with direct economic loss,rainfall,and maximum wind speed.展开更多
基金supported by the Special Funding of Marine Science StudyState Ocean Administration under contract No.20090513-2+2 种基金the National Natural Science Foundation of China under contract No.40976008Innovation Project from the Chinese Academy of Sciences under contract No.KZCX2-EW-209the Key program of Knowledge Innovation Project of Chinese Academyof Sciences under contract No.KZCX1-YW-12
文摘The effects of wave-induced radiation stress on storm surge were simulated during Typhoon Saomai using a wave-current coupled model based on ROMS （Regional Ocean Modeling System） ocean model and SWAN （Simulating Waves Nearshore） wave model. The results show that radiation stress can cause both set-up and set-down in the storm surge. Wave-induced set-up near the coast can be explained by decreasing significant wave heights as the waves propagate shoreward in an approximately uniform direction; wave-induced set-down far from the coast can be explained by the waves propagating in an approximately uniform direction with increasing significant wave heights. The shoreward radiation stress is the essential reason for the wave-induced set-up along the coast. The occurrence of set-down can be also explained by the divergence of the radiation stress. The maximum wave-induced set-up occurs on the right side of the Typhoon path, whereas the maximum wave induced set-down occurs on the left side.
基金National Natural Science Foundation of China(40730948,40830958,41105035, 40921160382)National Grand Fundamental Research 973 Program of China(2009CB421502)social commonweal research program(GYHY201006007)
文摘Recent studies have shown that surface fluxes and exchange coefficients are particularly important to models attempting to simulate the evolution and maintenance of hurricanes or typhoons.By using an advanced research version of the Weather Research and Forecasting(ARW)modeling system,this work aims to study the impact of modified exchange coefficient on the intensity and structures of typhoon Saomai(2006)over the western North Pacific.Numerical experiments with the modified and unmodified exchange coefficients are used to investigate the intensity and structure of the storm,especially the structures of the boundary layer within the storm.Results show that,compared to the unmodified experiment,the simulated typhoon in the modified experiment has a bigger deepening rate after 30-h and is the same as the observation in the last 12-h.The roughness is leveled off when wind speed is greater than 30 m/s.The momentum exchange coefficient(CD)and enthalpy exchange coefficient(CK)are leveled off too,and CD is decreased more than CK when wind speed is greater than 30 m/s.More sensible heat flux and less latent heat flux are produced.In the lower level,the modified experiment has slightly stronger outflow,stronger vertical gradient of equivalent potential temperature and substantially higher maximum tangential winds than the unmodified experiment has.The modified experiment generates larger wind speed and water vapor tendencies and transports more air of high equivalent potential temperature to the eyewall in the boundary layer.It induces more and strong convection in the eyewall,thereby leading to a stronger storm.
文摘Northwestern Pacific is the only ocean which has the most typhoon formation. The study of typhoon has far reaching significance today. Typhoon can relieve drought and make temperature drop substantially. Even we were suffering continuous high temperature in summer, the temperature would decrease immediately accompanied with typhoon. By using MODIS and weather station data to calculate the vegetation index, we analyze the drought characteristics of Shanghai during Saomai period, so that we can show the changes from the two aspects of the vegetation growth and the surface temperature. On the other hand, through the relative humidity data of Typhoon Saomai, we can find that the vegetation index and the relative humidity have been increased significantly. Typhoon rain also has its beneficial agricultural production side. It can lift the drought or ease the drought. It also provides abundant water resources for the growth of crops. In addition, the typhoon for the adjustment of the Earth’s heat, is contributed to maintain heat balance. Therefore, the typhoon to bring the changes in hydrothermal environment on the objective assessment of its impact and timely use of typhoon resources are of great significance.
基金National Science & Technology Pillar Program during the 11th Five-Year Plan Period,No.2007BAC29B05No.2008BAK50B02
文摘Tropical cyclone,a high energy destructive meteorological system with heavy rainfall and gale triggered massive landslides and windstorms,poses a significant threat to coastal areas.In this paper we have developed a Tropical Cyclone Potential Impact Index （TCPI） based on the air mass trajectories,disaster information,intensity,duration,and frequency of tropical cyclones.We analyzed the spatial pattern and interannual variation of the TCPI over the period 1949-2009,and taking the Super Typhoon Saomai as an example have examined the relationship between the TCPI and direct economic losses,total rainfall,and maximum wind speed.The results reveal that China＇s TCPI appears to be a weak decreasing trend over the period,which is not significant overall,but significant in some periods.Over the past 20 years,the TCPI decreased in the southern China coastal provinces of Hainan,Guangdong and Guangxi,while it increased in the southeastern coastal provinces of Zhejiang,Fujian and Taiwan.The highest values of TCPI are mainly observed in Taiwan,Hainan,the coastal areas of Guangdong and Fujian and Zhejiang＇s southern coast.The TCPI has a good correlation （P=0.01） with direct economic loss,rainfall,and maximum wind speed.
