Meteorological Observatory of Hainan

Haikou, China

Meteorological Observatory of Hainan

Haikou, China

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Wang Y.,Nanjing University of Information Science and Technology | Ding Z.,Nanjing University of Information Science and Technology | Li X.,Meteorological Observatory of Hainan
Journal of Natural Disasters | Year: 2014

GFS analytical data obtained by NCEP, satellite cloud image data and real-time observation data about the strength and path of tropical cyclone Morakot (2009) were applied to make a dynamic analysis of the evolution characteristics of structure and track before and after its landing on Taiwan Island. The results show that, first, it is possible for the lower levels of tropical cyclone and low value area of inertial stability on the outer side of the center of tangential wind to form radial wind to accelerate the radial flow, which will exert an influence on the structure distribution of tropical cyclone. Second, the ventilation flow and vortex center at the high and low levels caused by β effect will be of great significance in forecasting the path of tropical cyclone. Third, the structural evolution that the latitudinal of tropical cyclone stretched in the longitudinal direction and shrink in the zonal direction before and after landing will have effects on the speed of movement. Fourth, another important factor affecting the evolution of strength and structure of tropical cyclone is that the magnitude of the low-level convergence center and positive vorticity advection center should be equal. Last, the first and second modes of geopotential height anomaly field at500 hPa decomposed by EOF could disclose well the evolution of environment field of tropical cycloid.


Wang Y.,Nanjing University of Information Science and Technology | Ding Z.-Y.,Nanjing University of Information Science and Technology | Li X.,Meteorological Observatory of Hainan | Wang Q.,Yancheng Meteorological Observatory
Journal of Tropical Meteorology | Year: 2010

By using WRF mesoscale model, this paper carries out a numerical simulation and diagnostic analysis of the structural characteristics of the asymmetric spiral rain bands around the landing of Typhoon Haitang during the period of July 19 to 20, 2005. The result indicated that the two rainbands associated with the precipitation centre was mainly located northeast of the typhoon centre. The movement and intensity of the southern rainband corresponded well with the 850-hPa positive vorticity band from 0200 to 1800 UTC July 19, 2005. Under the effect of cyclonic circulation, the positive vorticity band at 850 hPa connected with a southern rain band, leading to the intensification of rainfall in the southern centre of the precipitation. The southward rainband gradually moved toward and then merges with the northward one, strengthening the rainfall in the northern centre of the precipitation. Besides, the relationship between the heavy rainfall and the divergence field of vertical shear wind in the high altitude is analyzed. Finally, the relationship is revealed between the development of the vertical component of convective vorticity vector and the rainfall near the two centres of precipitation in the low altitude.


Wang Y.,Nanjing University of Information Science and Technology | Ding Z.-Y.,Nanjing University of Information Science and Technology | Li X.,Meteorological Observatory of Hainan | Shen X.-Y.,Nanjing University of Information Science and Technology | Fan Y.,Nanjing University of Information Science and Technology
Journal of Tropical Meteorology | Year: 2014

NCEP GFS (Global Forecast System) analytical data (available 4 times per day), satellite cloud image data and real-time observations of path and intensity of Typhoon Morakot are employed to investigate the variation of synoptic dynamics in its intensity and structure before and after the landing. This study intends to offer some hints for the forecast of intensity and structure of typhoons. Results show that in the tangential direction, the averaged asymmetry amplitude of wind on the radius of a large-value center of the low-level wind can be used as an important parameter for diagnosing the intensity of typhoons. Besides, the maximum of the upper dry potential vorticity in Morakot's center tends to extend downward along the intensive gradient of tangential wind situated on the inner side of a large-value center of the low-level tangential wind. Additionally, the radial advection of the tangential wind determines the variation of tangential wind in conjunction with the vertical transmission of the tangential wind, the inertial centrifugal force and the Coriolis force. These four items are dominant in the motion equation of tangential wind based on a cylindrical coordinate without the effects of friction and turbulence. Moreover, the low-level convergence center of the typhoon has a tendency of shifting and developing along the intensive gradient of the tangential wind in the tangential direction.

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