| Several significant studies on Tropical Cyclone(TC) home and abroad has been reviewed comprehensively, including the researches on track variety and mesoscale convective systerm of TC.Typhoon Fengshen was poorly forecasted throughout its lifetime with all of the forecasts predicting that Fengshen would track to the northwest. Instead of this Fengshen tracked towards the west and traveled through the South China Sea after creating havoc in the Philippines, then hits on China.The satellite blackbody equivalent temperature data is used to investigate the possible mechanism leading to the great error in process of track prediction. The result shows that the existence of the mesoscale convective system (MCS) may account for the situation. By using non-hydrostatic WRF model, the typhoon Fengshen is simulated in high-resolution for better understanding the impact of the MCS produced in the west and southwest of the typhoon. In this paper, the simulation is double nesting with the highest resolution of 6km and integrated 78 hours. Comparing the simulated and observed typhoon maximum wind speed and sea level pressure, we find that they are almost the same trend and that path and the mesoscale simulation is well.In order to study the influence of mesoscale system to typhoon, this article introduces Wang and Zhang PV-co potential vorticity inversion method. This method based on the nonlinear balance in the improvement of latent heat, joined a dry friction and the vertical movement caused by dynamic process can diagnosis and inversion mesoscale system. PV-co piecewise Potential vorticity inversion diagnostic are applied to quantitatively diagnose the simulated data of typhoon Fengshen 1000 UTC 20 June. In this study, the individual contributions of latent heating, frictional, and dry dynamical processes to the FSCs of a hurricane vortex are separated in order to examine the contribution to the qusi-balance flow. It is shown that the latent heating FSC accounts for the most of the forced secondary circulations. The friction FSC is almost confined in the boundary layer (PBL) in the eye. In contrast, the dry dynamical forcing is determined by vertical shear and system-relative flow can account for proportion of vertical motion on typhoon core. It is found that the vertical wind shear tend to produce a counter shear vertical circulation in the typhoon core region. The shear FSC reduce one side of typhoon vertical motion and intense the opposite side, thus it accounts for the development of the circulation asymmetries. An idea mesoscale convective system superposed on the typhoon mean flow is constructed to examine the influence of various vertical shear and system relative flow. The result shows that the shear FSC is almost linearly related to the magnitude of environmental vertical shear with little changes in the circulation. The shear FSC may account for the persistence of the mesoscale system for the analysis shows that the FSC can intensify the disturbance aloft on the mesoscale system.The motion of a tropical cyclone is controlled by several major physical processes. PV-ωpiecewise Potential vorticity inversion diagnostic are applied to quantitatively evaluate the impact of the MCS to hurricane movement and to assess the influence to the hurricane's structure,results shows that the contribution of MSC to the steering flow can reach to 10%. Investigation of the effect of the MCS is also study by considering the non-existence of MCS as an initial-value problem. The non-existence of MCS simulation shows that the hurricane move to the right side of typhoon compared the unchanged simulation using WRF model output.
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