9406号台风与中纬度系统相互作用的中尺度特征

MESOSCALE CHARACTERISTICS OF THE INTERACTION BETWEEN TC TIM(9406) AND MID- LATITUDE CIRCULATION

利用非静力中尺度模式MM5,对9406号台风从1994年7月11日12时（世界时,下同）到12日12时之间的24h降水进行了模拟,采用滤波分析方法对模式结果进行了尺度分离。中尺度场的分析表明:台风与中纬度系统的相互作用非常显著地表现在中尺度系统的活动上;高低空中尺度散度场的分布对中低纬系统相互作用所产生的降水具有一定的指示意义;台风及西风槽强度的改变将直接导致中尺度系统强度的变化,从而造成降水强度的不同。另外,还从能量学角度对不同尺度系统的能量变化进行了分析。结果表明,中尺度场的能量变化极值区与中低纬度系统的强度变化密切相关,且与降水的变化有较好的对应关系。

With PSU/NCAR nonhydrostatic mesoscale model MM5, the 24 h rainfall during 12 UTC 11-12 UTC 12 July 1994 caused by Typhoon Tim (9406) is simulated in this paper. Scale discreting is performed on the results with filtering scheme. Analyses on the mesoscale fields show that the interaction between typhoon and westerly trough is apparently manifested by mesoscale activities. The distribution of divergence fields at lower and upper levels can have a kind of indication meaning for the rainfall caused by the interaction between mid and low latitude circulations. Furthermore, intensity changes of westerly trough would directly lead to intensity changes of mesoscale systems and thus lead to different rainfall. Besides, energy change features of different motion scales are also investigated from energetics point of view. The result shows that the maximum and minimum value areas of energy change on mesoscale fields are closely related to the intensity changes of mid and low latitude systems, and have rather good correlation with precipitation changes.