下垫面热状况对热带大气低频振荡影响的研究

本文利用一包含湿过程的简单热带大气滤波模式,通过引入辐合反馈机制和下垫面的蒸发效应对凝结潜热释放的贡献的物理过程,研究了下垫面热状况对热带大气季节内尺度低频振荡的作用过程。结果表明:下垫面性质特别是暖洋面的存在主要是减小低频振荡东传相速度和增大振幅,其中 Kelvin-Rossby 相互作用模在调制相速度和振幅的变化中起重要作用,因此,下垫面热状况是形成观测到的热带大气低频振荡局地特征的主要条件。

A STUDY OF INFLUENCE OF LOWER BOUNDARY THERMAL CONDITION ON LOW-FREQ UENCY OSCILLATION IN THE TROPICS

A simple moist and filtered model for the tropical atmosphere was con- structed,incorporated with a convergence feedback mechanism and a physical process of evaporation from the lower boundary contributed to the latent release due to condensation. By the model the dynamical processes of influences of lower boundary thermal conditions on low-frequency oscillation in the tropics were studied.The results represented by both the analytic solution and the numerical simulation indicate that the warm ocean can slow down the propagation of the low-frequency oscillation and also intensify the amplitudes. Therefore,the thermally non-uniform lower boundary is a necessary condition for for- mation of the observed local features of the low-frequency oscillation over the ocean in the tropics.