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

通过大气环流的动力-数值模式延长有用的预报期是正在进行的和拟议的大规模动态气象学研究中迅速增长的目标。最近在提高短程(0-5天)和中程(5-10天)数值预报的准确性和实用性方面取得的成功，激发了人们对发展能够在扩展(10天到季节性)范围及更远的范围内展示预报技能的模式相关问题的强烈兴趣。一项研究涉及一组观测到的大气流动现象，这些现象具有扩展范围和一般半球/全球空间尺度的特征变化周期(特别是中纬度“阻塞”、遥相关模式和急流及其相关风暴轨迹区域的纬向指数循环)。PI‘s建议在一套简单的理论模型中研究导致相似特征的开始和演化的过程，这些模型在他们之前的研究中表现出类似的行为。在这样简单的模式中理解这些过程，将有助于指导对目前用于实验动力扩展预报的更复杂的准业务模式的解的预报误差的解释，以及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.