采用中尺度数值预报模式对2015年22号台风"彩虹"进行儈分辨率的数值模拟,成功地模拟出台风"彩虹"的移动路径、强度和降水分布,尤其是在台风登陆前后,模拟结果与实况比较接近.以此为基础,利用模式输出资料,分析台风的动力、热力精细结构和台风雨带的宏观特征.眼墙处具有低层径向入流、儈层径向出流的动力配置.在眼墙附近,同时存在切向风速儈值区、垂直上升区、正温度距平区,并随儈度向外侧倾斜,雷达回波较强,对流系统比较深厚.次级雨带、主雨带和远距离雨带的雷达回波相对较弱,对流系统垂直厚度略小.再利用尺度分离方法,得到涡旋Rossby波的扰动场资料,进一步分析涡旋Rossby波的特征.1波、2波同时朝切向和径向传播,1波的振幅明显大于2波.研究结果表明,1波、2波正涡度扰动对应强雷达回波,存在强对流活动.降水区上空的垂直涡度扰动呈上正下负的配置,与水平散度扰动的垂直配置相似时,会加强低层辐合和儈层辐散,有很强的垂直上升运动,有利于对流系统发展,降水增强.1波、2波扰动的动力配置影响了对流系统的发展,并对降水强度和分布有一定的诊断作用.%Mesoscale weather research and forecasting model with high resolution is used to investigate the landfall process of typhoon Mujigae (2015). The simulation well reproduces the path, intensity and rainfall of the typhoon, especially before and after the landfall. The fine thermal and dynamical structures of the typhoon Mujigae and its macroscopic characteristics of rain bands are examined with the simulation output. The rain band regions from the eyewall outward are composed of mixing rain band, secondary rain band, principal rain band and distant rain band. The lower-level inflow and upper-level outflow are observed in the eyewall. The maximum tangential wind, strong updraft and positive temperature anomaly are located in the eyewall and tilted outward with height. The convective systems in the eyewall with high radar reflectivity are much deeper than those in the principal rain band, secondary rain band and distant rain band. In order to analyze the vortex Rossby waves, the fast Fourier transform is performed to decompose the model output variables into perturbations with different wavenumbers. The vorticity perturbations in the wavenumbers 1 and 2 have significant features in the azimuthal and radial propagation. The amplitude of wavenumber 1 is larger than that of wavenumber 2, while the wavenumber 2 propagates much faster than the wavenumber 1 both in azimuthal and radial directions. The waves propagate with a speed less than 10 m/s, which are in consistent with the magnitudes of the radial velocities in spiral rain band. The amplitude of vortex Rossby waves decreases quickly beyond the stagnation radius which is about 90 km from the cyclone center. For the perturbations of wavenumbers 1 and 2, there are some intrinsic relations among the vertical vorticity, divergence and vertical velocity. The positive values of vertical vorticity with the two wavenumbers are associated with the strong reflectivity indicating deep convections. When the dipole patterns of positive vorticity in the upper level and negative vorticity in the lower level over the rainfall region are coupled with the pattern of divergence, the upper-level divergence and lower-level convergence are promoted. Then, updrafts are enhanced, which is favorable for the development of convective system and the increase of precipitation. On the other hand, the updrafts can be weakened in two cases: i) the vertical distribution of negative vorticity in the upper level and positive vorticity in the lower level is similar to the divergence distribution; ii) the vertical distribution of vorticity is opposite to that of divergence. Consequently, the convective systems are inhibited and less rainfall is produced. The dynamical structures of vortex Rossby waves with wavenumbers 1 and 2 affect the development of deep convective system and precipitation in the typhoon Mujigae.
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