Stability of Atmospheric Shear Flows and Eddy Characteristics

Mahrt教授将利用非线性稳定性分析技术（能量-卡西米尔方法）重新研究分层流中剪切不稳定性的发展和湍流的产生。初步研究表明，临界理查德森数一般大于0.25，但取决于平均流型的曲率。虽然这种稳定性分析比以前的分析更一般，但在确定结果之前必须检查一些技术要点。最有趣的是这种方法和埃克曼不稳定性预测的差异。这些分析结果将与在平坦地形稳定条件下（丹麦里索）收集的前所未有的大量高质量塔台数据样本进行比较，并将在随后的几次气象现场实验中应用于边界以上收集的快速响应飞机数据。目的是评估湍流发展与平均风廓线和潜在温度之间的关系。//

Professor Mahrt will reexamine the development of shear- instability and generation of turbulence in stratified flow by employing nonlinear stability analysis techniques (energy-Casimir approach). Preliminary work indicates that the critical Richardson number is generally larger than 0.25 but depends on the curvature of mean flow profile. While this stability analysis is more general than previous analyses, a number of technical points must be examined before results can be developed with confidence. Most interesting are differences predicted by this approach and those of Ekman instability. These analytical results will be compared to an unprecedented large sample of high-quality tower data collected in stable conditions over flat terrain (Riso, Denmark) and will also be applied to fast response aircraft data collected above the boundary later in several meteorological field experiments. The objective is to assess the relationship between turbulence development and the mean profile of wind and potential temperature.//