Abstract Dike failure and marine losses are quite prominent in Laizhou Bay during the period of cold wave storm surges because of its open coastline to the north and fiat topography. In order to evaluate the intensity...Abstract Dike failure and marine losses are quite prominent in Laizhou Bay during the period of cold wave storm surges because of its open coastline to the north and fiat topography. In order to evaluate the intensity of c01d wave storm surge, the hindcast of ma- rine elements induced by cold waves in Laizhou Bay from 1985 to 2004 is conducted using a cold wave storm surge-wave coupled model and the joint return period of extreme water level, concomitant wave height, and concomitant wind speed are calculated. A new criterion of cold wave storm surge intensity based on such studies is developed. Considering the frequency of cold wave, this paper introduces a Poisson trivariate compound reconstruction model to calculate the joint return period, which is closer to the reality. By using the newly defined cold wave storm surge intensity, the ＇cold wave grade＇ in meteorology can better describe the severity of cold wave storm surges and the warning level is well corresponding to different intensities of cold wave storm surges. Therefore, it provides a proper guidance to marine hydrological analysis, disaster prevention and marine structure design in Laizhou Bay.展开更多
A crucial issue in evolution of severe storm, such as typhoon and even singlesupercell, is to diagnose and predict the sudden intensifying in storm. This paper describes anattempt to investigate the influence and effe...A crucial issue in evolution of severe storm, such as typhoon and even singlesupercell, is to diagnose and predict the sudden intensifying in storm. This paper describes anattempt to investigate the influence and effect of ambient moisture in the development of storm. Itwas mainly through a dynamic way to detect the helical enhancement by ambient moisture. It was foundthat the correlation between the ambient moistness and the intensity of rotating convective cellscan be well analyzed by helicity dynamics. The correlation between environmental streamwisevorticity (i. e. helicity) and vertical velocity (storm updraft or downdraft) is a powerfulindicator to catch favorable or unfavorable conditions for storm evolution. For this purpose, athree-dimensional non-hydrostatic storm-scale model, Advanced Regional Prediction System CARPS) wasemployed in order to numerically simulate a well-documented case of Del City supercell storm indifferent kinds of environmental moistness. Moreover, such different kinds of ambient moistenvironment and the resultant different morphologies and evolutions in the storm clearlydemonstrated that the abundant moistness in the environment that the storm embedded significantlystrengthens tbe storm intensity. In fact, the storm is embedded in much moist environment andtherefore larger instability propagates faster than the one in the drier air. It further producesstronger low-level mesocyclone with a much longer lifetime. The stronger convection and twist in theupdraft indicates that helical enhancement effect by moisture lead to stronger tornadic activity insevere storm.展开更多
The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the ef...The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the effects of the solar wind dynamic pressure and the quiet time ring current.However,all previous studies treated the correction coefficient as an averaged parameter for storms of different intensity.In this paper,based on the Burton's equations and employing two independent methods,we will show a positive correlation between pressure-correction coefficient b and the intensity of the storms.We divided our storm database(872 storms in total) into three categories according to the intensity of storms.In order to improve the accuracy of calculating,we also used the higher-resolution SYM-H index data instead of Dst index to compute the corrected Dst index during different storms.Furthermore,we are able to provide corrected magnetic storm index with high-time resolution(-1 min).展开更多
基金partially supported by the National Natural Science Foundation of China (Nos.51279186,51479183)the National Key Research and Development Program (Nos.2016YFC0303401,2016YFC0802301)
文摘Abstract Dike failure and marine losses are quite prominent in Laizhou Bay during the period of cold wave storm surges because of its open coastline to the north and fiat topography. In order to evaluate the intensity of c01d wave storm surge, the hindcast of ma- rine elements induced by cold waves in Laizhou Bay from 1985 to 2004 is conducted using a cold wave storm surge-wave coupled model and the joint return period of extreme water level, concomitant wave height, and concomitant wind speed are calculated. A new criterion of cold wave storm surge intensity based on such studies is developed. Considering the frequency of cold wave, this paper introduces a Poisson trivariate compound reconstruction model to calculate the joint return period, which is closer to the reality. By using the newly defined cold wave storm surge intensity, the ＇cold wave grade＇ in meteorology can better describe the severity of cold wave storm surges and the warning level is well corresponding to different intensities of cold wave storm surges. Therefore, it provides a proper guidance to marine hydrological analysis, disaster prevention and marine structure design in Laizhou Bay.
文摘A crucial issue in evolution of severe storm, such as typhoon and even singlesupercell, is to diagnose and predict the sudden intensifying in storm. This paper describes anattempt to investigate the influence and effect of ambient moisture in the development of storm. Itwas mainly through a dynamic way to detect the helical enhancement by ambient moisture. It was foundthat the correlation between the ambient moistness and the intensity of rotating convective cellscan be well analyzed by helicity dynamics. The correlation between environmental streamwisevorticity (i. e. helicity) and vertical velocity (storm updraft or downdraft) is a powerfulindicator to catch favorable or unfavorable conditions for storm evolution. For this purpose, athree-dimensional non-hydrostatic storm-scale model, Advanced Regional Prediction System CARPS) wasemployed in order to numerically simulate a well-documented case of Del City supercell storm indifferent kinds of environmental moistness. Moreover, such different kinds of ambient moistenvironment and the resultant different morphologies and evolutions in the storm clearlydemonstrated that the abundant moistness in the environment that the storm embedded significantlystrengthens tbe storm intensity. In fact, the storm is embedded in much moist environment andtherefore larger instability propagates faster than the one in the drier air. It further producesstronger low-level mesocyclone with a much longer lifetime. The stronger convection and twist in theupdraft indicates that helical enhancement effect by moisture lead to stronger tornadic activity insevere storm.
基金supported by the Key Project of the National Natural Science Foundation of China (Grant No 40831061)
文摘The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the effects of the solar wind dynamic pressure and the quiet time ring current.However,all previous studies treated the correction coefficient as an averaged parameter for storms of different intensity.In this paper,based on the Burton's equations and employing two independent methods,we will show a positive correlation between pressure-correction coefficient b and the intensity of the storms.We divided our storm database(872 storms in total) into three categories according to the intensity of storms.In order to improve the accuracy of calculating,we also used the higher-resolution SYM-H index data instead of Dst index to compute the corrected Dst index during different storms.Furthermore,we are able to provide corrected magnetic storm index with high-time resolution(-1 min).
