非对称型强飓风中的准平衡流特征分析Ⅱ:波动结构  

The diagnoses of quasi-balanced flows in asymmetric intense hurricane.Part Ⅱ:Wave structure

作　　者：钟玮[1] 陆汉城[1] 张大林[2] 

机构地区：[1]解放军理工大学气象学院,南京211101 [2]马里兰大学大气和海洋科学系,美国马里兰州20742

出　　处：《地球物理学报》2010年第11期2551-2563,共13页Chinese Journal of Geophysics

基　　金：国家重点基础研究发展规划项目(2009CB421500);国家青年科学基金项目(40905022);国家自然科学基金重点项目(40830958)资助

摘　　要：利用非对称波分量分解和小波分析的方法,对准平衡动力模型下非对称强飓风内中尺度波动的空间结构和时间序列特征进行分析.结果表明,平衡流场中1波扰动占主要地位且具有涡旋Rossby波的典型结构特征,准平衡流各波数下扰动的空间分布反映了中尺度波动的混合性质;模式大气和准平衡垂直运动的全局功率谱中,超过信度检验的强波动信号中不仅包含分别表征重力波和涡旋Rossby波的高频和低频波动信号,还存在表征具有物理性质不可分特性的混合涡旋Rossby-重力波的中频波动.混合波的出现建立了不同频段波动之间的能量交换通道,其信号的变化对飓风系统的强弱变化具有一定的指示作用.非平衡垂直运动的波动强信号则主要集中在高频和低频区域,反映了在飓风强度变化情况下,与高频重力波有关的快波调整过程所引起的垂直扰动的振荡和传播.强垂直风切变对飓风内中尺度波动的切向和径向传播具有重要影响,当环境垂直风切变很强时,准平衡1波扰动在径向和切向方向上均呈"驻波"形态,随着环境垂直风切变的减弱,1波扰动以混合波波速逆基本气流传播.In this paper, the spatial structure and time series of mesoscale wave under the quasi- balanced model in an asymmetrical intense hurricane are investigated by using the method of asymmetric wave decomposition and wavelet analysis. The results show that the wavenumber （WN）-I component of balanced flows predominated and manifest the typical feature of vortex Rossby waves （VRWs）, while the spatial distribution of every components reflect the mixed feature of mesoscale waves. The results from wavelet analysis indicate that the strong wave signals of simulated and quasi-balanced vertical velocity, which exceed the significance levels, contain the high-frequency waves of inertial-gravity waves （IGWs）, the low-frequency waves of VRWs, and the middle-frequency waves of mesoseale mixed vortex Rossby-gravity waves （VRGWs）. These mixed wave signals establish the path for exchanging the energy among different wavebands. The appearance and disappearance of mixed VRGWs signals are related to the violence development and weakening of TC. The strong wave signals of unbalanced vertical velocity concentrate in the two regions with high and low frequency, reflecting that the forming and propagation of unbalanced vertical perturbation is the adjustment process relating to the high frequency gravity waves, which is influenced by the intensity change of TC. Environmental vertical wind shear plays an important role in the propagation of waves. When the shear is strong, the WN-1 component in quasi-balanced flows appears to be ＇standing waves＇ both in tangential and radial direction. However, with the decreasing of vertical shear, the WN-1 component propagates contrary to the basic flows at the phase speed of mixed waves.

关 键 词：中尺度波动 准平衡流 PV-ω反演 

分 类 号：P433[天文地球—大气科学及气象学]