“天鹅”台风风场结构特征

Analysis on the Structure Characteristics of Typhoon Goni

为了进一步认识台风的动力结构特点,利用组网天气雷达产品三维格点反射率因子资料与两步变分法反演出三维风场,对2009年第7号台风天鹅风场结构做了分析,结果表明:两步变分法较好地反演出"天鹅"台风的水平环流结构;在4km高度上,最大风圈半径内,平均切向风速接近Rankine涡旋模型,通过拟合该高度上最大风圈半径上的切向速度,得到具有周期为2π的正弦形式的函数,说明"天鹅"台风具有非对称波数为1的特征;通过垂直剖面上的结构特点分析,说明"天鹅"台风在低层并不具有一致的入流气流,而在高层也不具有一致的出流气流。

In this paper,the dynamic characteristics of typhoon Goni,the No.9 typhoon of 2009,were analyzed with the three-dimentional grid reflectivity generated by Cinrad Mosaic System developed by the State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences and the wind field retrieved by a two-step variational method proposed by Qiu.The main results show that;（1） Horizontal component of wind retrieved by the two-step variational method demonstrated the vortex structure of typhoon Goni very well.The tangential component of wind was of unsymmetrical distribution with wavenumber 1;（2） Within the radius of maximum wind（RMW）,the mean tangential component of wind increased linearly according to the increasing distance away from the center of Goni at the height of 4 km, and quite nearly the famous Rankine vortex model;（3） The inflows did not run into the center of Goni at all azimuths at low levels and at upper levels the outflows did not run out of the center of Goni in all directions, either.