Stability of Zonally Varying Basic Flows and the Inter- actions Between Planetary and Synoptic Waves

通过大气环流的动力数值模式来延长有用预报的周期，是正在进行和正在提出的大尺度动力气象学研究的一个迅速增长的群体的目标。最近，在提高短期（0-5天）和中期（5-10天）数值预报的准确性和实用性方面取得了成功，这激发了人们对开发能够在较长（10天至季节性）范围内展示预报技能的模型相关问题的强烈兴趣。一条研究路线涉及一系列观测到的大气流动现象，这些现象具有广泛范围内的特征变化周期，通常是半球/全球空间尺度（特别是中纬度“阻塞”、遥相关模式和急流及其相关风暴路径区域的纬向指数周期）。PI建议在一套简单的理论模型中研究导致相似特征开始和进化的过程，这些模型在他们之前的研究中表现出类似的行为。在这样简单的模型中理解这些过程将有助于指导解释目前用于实验动态扩展范围预测的更复杂的准操作模型的解中的预测误差，并逐步消除这些误差的来源。

Extension of the period of useful forecasts by dynamical- numerical models of the atmospheric circulation is the goal of a rapidly growing body of ongoing and proposed research in large scale dynamic meteorology. Recent success in improving the accuracy and utility of short (0-5 day)-, and medium (5-10 day)-range numer- ical forecasts has stimulated intensified interest in the problems associated with developing models that can exhibit forecast skill in the extended (10 day to seasonal)-range and beyond. One line of research concerns the set of observed atmospheric flow phenomena with characteristic periods of variation in the extended range, and generally of hemispheric/global spatial scale (in particular, mid- latitude "blocking", teleconnection patterns, and zonal index cycles of the jet-stream and its associated storm-track regions). The PI's propose to study the processes leading to the onset and evolution of similar features in a suite of simple theoretical models which have exhibited similar behavior in their prior research. Understanding these processes in such simple models will help to guide the interpretation of forecast errors in the solu- tions of the more complex quasi-operational models now being used in experimental dynamical extended-range forecasts, and the step- wise elimination of the sources of these errors.