Persistent Flow Anomalies, Blocking and Variations in Synoptic-Scale Eddy Activity. Theoretical and Diagnostic Studies

这项研究的主要目的是更好地了解决定大规模流动异常(如堵塞)演变的机制。第二个主要目标是确定大尺度流量异常如何影响天气尺度涡旋(并受其影响)。为了实现这些目标，将采用多种方法相结合的方法来研究天气尺度涡旋活动的变化，以及各种动力和物理过程在大尺度流量异常演变的不同阶段中的作用。拟议研究的具体目标包括：应用天气学和诊断学方法分析和比较NCAR社区气候模式低频变率的数值模拟与相应的观测结果，特别强调评估持续异常和阻塞的结构和生命周期模式模拟的充分性。还将利用诊断分析来研究在大尺度流型演变的不同阶段(即发展阶段、成熟阶段和崩溃阶段)大尺度流动异常与天气尺度涡旋活动变化之间的关系(在模式和观测中)。此外，还将扩展现有的阻塞分析和理论模型，特别集中于Malguzzi和Malanotte-Rizzoli(1984)以及Haines和Matt(1987)的相干结构模型。这些模型将被用来进一步研究各种动力和物理过程在异常大尺度流型的开始、持续和破裂中所起的作用。这项工作将增强我们作出季节性预报的能力。

The primary goal of this research is to obtain an improved understanding of the mechanisms that determine the evolution of large-scale flow anomalies such as blocking. A second major goal is to determine how the large-scale flow anomalies may influence (and be influenced by) synoptic-scale eddies. In order to achieve these goals, a combination of approaches will be employed to study the variations in synoptic-scale eddy activity and the roles of various dynamical and physical processes during different stages in the evolution of the large-scale flow anomalies. Specific objectives of the proposed studies include: applying synoptic and diagnostic approaches to analyze and compare numerical simulations of low-frequency variability in the NCAR Community Climate Model with corresponding observational results, with particular emphasis given to assessing the adequacy of model simulation of the structures and life cycles of persistent anomalies and blocking. Diagnostic analyses will also be employed to examine the relationships (in both the model and observations) between the large-scale flow anomalies and changes in synoptic-scale eddy activity at various stages in the evolution of the large-scale flow patterns (i.e., during the development, mature and breakdown stages). In addition, extensions to current analytical and theoretical models of blocking will be developed, concentrating particularly on the coherent structure models of Malguzzi and Malanotte-Rizzoli (1984) and Haines and Marshall (1987). These models will be employed to further examine the roles played by various dynamical and physical processes in the initiation, persistence and breakdown of the anomalous large-scale flow patterns. This work will enhance our capability to make seasonal forecasts.