扰动动能的气候特征及其与平均风场的关系

THE CLIMATOLOGICAL CHARACTERISTICS OF THE PERTURBATION KINETIC ENERGY AND ITS RELATION WITH THE MEAN WINDS

本文应用美国NMC全球客观分析格点资料分析了全球扰动动能(PKE)的气候特征,结果表明,纬向平均的PKE分布与纬向平均的u风分量分布有密切的关系。PKE的最大值与西风的最大值相对应,而最小值则与东风的最大值相对应。PKE随经度也有明显的变化。在中纬度,PKE的高值区位于西风急流中心或其下游,而PKE的低值区则位于急流中心的上游。在热带,PKE的高值区位于西风区或弱东风区,PKE的低值区则位于强东风带。中纬度地区,对流层上层PKE随经度的变化与对流层下层是同位相的。而在热带地区,上下层PKE随经度的变化则是反位相的。 本文还对PKE的产生机制进行了探讨。指出中纬度PKE主要与斜压扰动相联系,而热带地区PKE的来源则与中纬度波动向热带的传播及热带内部波动的纬向传播有关。

In this paper the global distribution of the perturbation kinetic energy (PKE)is analysed using the NMC grid point data set. It is found that zonally averaged PKE is closely linked with the clima-tological mean value of U wind component. The PKE also has strong longitudinal variation. In middle latitudes the high value of PKE locates in the core area of westerly jet or its downstream area, while the low value of PKE lies in the upstream area of the westerly jet. In the tropics the high PKE is in the westerlies or the weak easterlies and the low PKE is in the strong easterlies. The PKE of upper troposphere in-middle latitudes is in phase with the PKE of low troposphere, but they' are out of phase in the topics. The generation mechanism of the PKE is also discussed in this paper.