正压大气有利发展扰动型与遥相关型的建立

Preferred Perturbations of Growth in the Barotropic Atmosphere and Dynamics of Teleconnection

本文讨论了夏季纬向不对称气候平均流下通过正压大气内部动力过程建立遥相关型的问题。首先详细描述和讨论了有利发展扰动型的概念及其计算方法。作为对比，对正规模不稳定进行了分析。结果表明，正规模的不稳定增长率很小，难以用于解释遥相关型的发展。而有利发展扰动型的计算分析表明，最有利发展的那些扰动型的振幅增长率同实际大气遥相关型的增长率相一致，并且这些有利发展扰动型都将演变为同实际大气相一致的遥相关型结构．从而提出了，至少部分实际大气遥相关型可以不依赖于异常外源强迫，而仅依赖于大气内部的正压过程即能量转换过程而建立起来。

The goal of this study is to determine whether the generation of teleconnection patterns can resultsolely from the internal barotropic processes of the zonally varying climatoloical flow in the northern summer. The results of analysis of normal modes indicate that the growth rate of unstable normal modes is insufficient to explain the generation of realistic teleconnection patterns. Then, a concept of preferred Perturbation of growth is introduCed. An approach to find the prefeed perturbances of growth is described in detail. The results of calculations show that the amplification rate of the leading preferred perturbations of growth is consistent with that of realistic teleconnection patterns. Moreover,they evolve into the structure of realistic teleconnection patterns. The preferred perturbation of growth possesses highly localized spatial structures with the wavetrain appearance, most of them are localized to the south of regions of the jet cores. It is suggested that at least some of teleconnection patterns can form as a consequence of internal barotiopic processes of the zonally asymmetrical basic state , but de pend on the preferred perturbations of growth, which have larger growth rate than that of unstable normal modes.