| 摘要: |
| 本文利用线性化的能量方程和交叉谱方法分别研究了准两周振荡和准40天振荡的能量来源及其转换过程。发现:在热带对流层中,对于低频振荡过程来说,来自中高纬度的侧向强迫作用和水汽凝结的加热作用是非常重要的,为扰动的产生和维持提供了重要能源。而正、斜压不稳定作用对扰动发展的作用是极小的。并且指出,在东亚热带对流层上部,准两周振荡通过与平均气流的相互作用为基本气流提供许多能量,对于维持这里的高空东风急流有重要作用。准40天振荡向平流层输送能量,对平流层平均环流的演变可能有重要贡献。 |
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| AN ENERGETIC STUDY OF LOW FREQUENCY OSCILLATIONS IN THE TROPICAL TROPOSPHERE |
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Wu Peili1, Luo Huibang2
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1.Air Force Institue of Meteorology;2.Department of Atmospheric Science, Zhongshan University
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| Abstract: |
| Based on the data of April to June of 1981, the energetic processes of 14-day and 40-day oscillations were examined respectively. Eddy kinetic energy for both oscillations is generated mainly by meridional convergence of wave energy flux and conversion from eddy available potential energy, while the eddy available potential energy is generated by heating of condensation, suggesting possible excitation of the oscillations by lateral forcing due to midlatitude disturbances and sho-wing the importance of CISK in the maintenance of oscillation’s. The estimates show that the barotropic and baroclinic instabilities are less important, but the quasibiweekly oscillation can provide energy for the mean zonal flow in the upper troposphere of east Asia to maintain the upper level jet stream. On the other hand, a large amount or vertical wave energy flux from troposphere to stratosphere may be related to the existence of the 40-day oscillation. |
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