2006年超强台风“桑美”强度突变的动能特征分析

ANALYSIS OF KINETIC ENERGY FEATURE OF ABRUPT INTENSITY CHANGE OF SUPER TYPHOON SAOMAI(0608)

应用NCEP/NCAR再分析资料,对2006年超强台风"桑美"(Saomai)强度突变过程的动能特征进行分析,结果表明:"桑美"突然增强时刻其低层总动能和旋转风动能突然增加,辐散风动能也有所增加,总动能的增加主要是由旋转风动能增加所引起的;其高层总动能和旋转风动能突然减小,而辐散风动能突然增加,高层动能下传是导致"桑美"突然增强的重要原因;"桑美"突然增强时刻高层辐散风动能向旋转风动能的转换达到最大,低层辐散风与旋转风相互作用动能项达到最大;"桑美"突然减弱时刻的高低层能量变化趋势与突然增强时刻相反,并存在着低层动能的上传;"桑美"强度突变时对总动能(K)、旋转风动能(KR)、辐散风动能(KD)变化的响应时间为6～18 h。

An energy diagnostic analysis is applied in the abrupt intensity change stage of super typhoon Saomai（0608）, especially concerning the kinetic energy feature. The results show that the total kinetic energy and therotationalkinetic energy（KR） in the lower troposphere increase suddenly during the rapid intensification（R/） stage of the typhoon. Meanwhile, these two kinds of energy in the upper levels significantly decrease while the divergent kinetic energy（Ko） rises. The downward transport of the upper tropospheric kinetic energy is a major cause of the RI phenomenon. The conversion of the KR and Ko reaches the maximum in the RI stage, kinetic energy for the interaction of divergent wind with rotational wind stays high in the R1 stage. Each kinetic energy distribution trend of the whole layer is out-of-phase in a rapid weakening（RW） stage, with an upward transport of the lower tropospheric kinetic energy. There may be a 6 h to 18 h response time for the total kinetic energy and its three components to reach their max. or rain. when the RI or RW occurs.