In this paper, using Holland's method, the effect of the horizontal structure of tropical cyclones on their motion is investigated. The 'characteristic radius', r0 characterized as the horizontal structure...In this paper, using Holland's method, the effect of the horizontal structure of tropical cyclones on their motion is investigated. The 'characteristic radius', r0 characterized as the horizontal structure of a tropical cyclone,in which m and p are the parameters of the vortex, has been found by the author. And then it has been shown that there is but one 'characteristic radius' for each cyclone with horizontal structure. Two direct analytic solutions for the uniform and non-uniform basic flows in steady situations are presented with rc Results show that the change in the horizontal structure of the tropical cyclone itself will have obvious effect on the cyclone motion, on both its direction and speed. Therefore it must be considered in the research on the tropical cyclone motion.展开更多
A barotropic prirnitive equation model is used to simulate the tropical cyclone motion.Tropical cyclone movements under different environmental flow backgrounds were examined and sensitivity of tropical cyclone tracks...A barotropic prirnitive equation model is used to simulate the tropical cyclone motion.Tropical cyclone movements under different environmental flow backgrounds were examined and sensitivity of tropical cyclone tracks were discussed.Conclusions of practical significance have been obtained in this paper.展开更多
The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between ...The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between the ventilation flow vector and the motion vector of the tropical cyclone is inves- tigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropi- cal cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventila- tion flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.展开更多
Impacts of small-scale vortices on typhoon or tropical cyclone（TC） tracks in a system of three components （an idealized subtropical high ridge,a TC,and small-scale vortices） were examined numerically using a barot...Impacts of small-scale vortices on typhoon or tropical cyclone（TC） tracks in a system of three components （an idealized subtropical high ridge,a TC,and small-scale vortices） were examined numerically using a barotropic primitive equation model and idealized initial fields.Two small-scale vorticity fields were generated stochastically,where the number of initial small-scale vortices is 100.In the two fields,the number, size,structure as well as the total kinetic energy of the small-scale vortices were all the same,but their center coordinates were randomly distributed.Two experiments,named EXA and EXB,with the integration time of 56 h,were performed. Comparison of the integration outputs from the two experiments indicates that various small-scale vorticity fields involved could produce both various horizontal winds in the TC outer area and various intensities of the environmental steering for TC.The values of the environmental flow speed along the east-west direction are 7.8,8.2,and 8.7 m s^（-1） in EXA and 8.3,9.5,and 9.7 m s^（-1） in EXB at t = 24,36,and 48 h,respectively. The values along the south-north direction are 0.9,1.8,and 2.5 m s^（-1） in EXA and 2.3,2.3,and 5.9 m s^（-1） in EXB,respectively.The various intensities of the environmental steering could lead to various TC center positions.For example,the difference between the coordinates of TC centers in EXA and EXB reaches 120 km at t = 48 h,which is about 56%of the prediction error of TC tracks in the northwestern Pacific region derived from eight operational models. Dynamics of the interplays between a subtropical high ridge and a TC in previous works has shown that when the TC was located equatorwards of the subtropical ridge,the relationship between the propagation of TC and the local absolute vorticity gradient was characterized by points scattered around their mean values.After introducing the stochastic vorticity field into the model,the interplays among the subtropical high ridge,the TC,and small-scale vortices might make this relationship more complex,that is,besides the scattered points,there also exists a high correlation between the propagation of TC and the local absolute vorticity gradient.展开更多
文摘In this paper, using Holland's method, the effect of the horizontal structure of tropical cyclones on their motion is investigated. The 'characteristic radius', r0 characterized as the horizontal structure of a tropical cyclone,in which m and p are the parameters of the vortex, has been found by the author. And then it has been shown that there is but one 'characteristic radius' for each cyclone with horizontal structure. Two direct analytic solutions for the uniform and non-uniform basic flows in steady situations are presented with rc Results show that the change in the horizontal structure of the tropical cyclone itself will have obvious effect on the cyclone motion, on both its direction and speed. Therefore it must be considered in the research on the tropical cyclone motion.
文摘A barotropic prirnitive equation model is used to simulate the tropical cyclone motion.Tropical cyclone movements under different environmental flow backgrounds were examined and sensitivity of tropical cyclone tracks were discussed.Conclusions of practical significance have been obtained in this paper.
基金This work is supported by the 8th Five-Year Project of Key Item Research of China under Grant 85-906-07-02-04.
文摘The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model. The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components. The relation between the ventilation flow vector and the motion vector of the tropical cyclone is inves- tigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropi- cal cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventila- tion flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.
基金Supported by the National Natural Science Foundation of China under Grant Nos.40775038,40975036,and 40875031
文摘Impacts of small-scale vortices on typhoon or tropical cyclone（TC） tracks in a system of three components （an idealized subtropical high ridge,a TC,and small-scale vortices） were examined numerically using a barotropic primitive equation model and idealized initial fields.Two small-scale vorticity fields were generated stochastically,where the number of initial small-scale vortices is 100.In the two fields,the number, size,structure as well as the total kinetic energy of the small-scale vortices were all the same,but their center coordinates were randomly distributed.Two experiments,named EXA and EXB,with the integration time of 56 h,were performed. Comparison of the integration outputs from the two experiments indicates that various small-scale vorticity fields involved could produce both various horizontal winds in the TC outer area and various intensities of the environmental steering for TC.The values of the environmental flow speed along the east-west direction are 7.8,8.2,and 8.7 m s^（-1） in EXA and 8.3,9.5,and 9.7 m s^（-1） in EXB at t = 24,36,and 48 h,respectively. The values along the south-north direction are 0.9,1.8,and 2.5 m s^（-1） in EXA and 2.3,2.3,and 5.9 m s^（-1） in EXB,respectively.The various intensities of the environmental steering could lead to various TC center positions.For example,the difference between the coordinates of TC centers in EXA and EXB reaches 120 km at t = 48 h,which is about 56%of the prediction error of TC tracks in the northwestern Pacific region derived from eight operational models. Dynamics of the interplays between a subtropical high ridge and a TC in previous works has shown that when the TC was located equatorwards of the subtropical ridge,the relationship between the propagation of TC and the local absolute vorticity gradient was characterized by points scattered around their mean values.After introducing the stochastic vorticity field into the model,the interplays among the subtropical high ridge,the TC,and small-scale vortices might make this relationship more complex,that is,besides the scattered points,there also exists a high correlation between the propagation of TC and the local absolute vorticity gradient.
