Predictability and Maintenance of Variance in Atmospheric Flows

小行星9623539 该奖项继续支持旨在发展大气流动一般稳定性理论以及中纬度急流等强剪切流中湍流动力学理论的研究。 主要研究者将使用理论模型和模拟分析与大气环流模型（GCM）的组合来追求这些目标。 该项目包括两个主要目标。 第一个奖项建立在上一个奖项完成的理论工作基础上。 其目的是确定的方差和通量保持的随机强迫的GCM与现实的纬向变化的射流结构，并比较这些方差和通量的GCM的长时间积分的统计手段。 将使用NCAR社区气候模型（CCM 2）的一个版本。 希望这项研究将有助于阐明在特定区域产生风暴局部化的动力学以及风暴路径对变化的敏感性。 该项目将与NCAR科学家合作完成。 第二个研究重点是对湍流模式系统和大气环流模式中的基本算子及其稳定性进行更理论化和更广泛的研究。 如果时间允许，还将增加一个专题。 本研究将研究时间相关流的稳定性-特别是，时间平均流的扰动的瞬态增长和出现的第一个李雅普诺夫模式和非正态性的作用，在支持短时间误差增长和渐近李雅普诺夫模式之间的关系。 ***

9623539 Farrell The award continues support for research aimed at developing a general stability theory for atmospheric flows as well as a theory for the dynamics of turbulence in strongly sheared flows such as the midlatitude jet. The principal investigator will pursue these goals using a combination of theoretical models and analysis of simulations with a general circulation model (GCM). The project involves two major thrusts. The first builds on theoretical work completed under the last award. The aim is to determine the variance and fluxes maintained by stochastic forcing of a GCM with realistic zonally varying jet structure and to compare these variances and fluxes with those obtained from the statistical means of a long time integration of the GCM. A version of NCAR's Community Climate Model (CCM2) will be used. It is hoped that this study will shed light on the dynamics responsible for producing localization of storms in particular regions and the sensitivity of storm tracks to alteration. The project will be done in collaboration with an NCAR scientist. The second research focus involves a more theoretically focused and generalized study of the underlying operator in turbulent model systems and GCMs and its stability properties. An additional topic will be undertaken if time permits. This study will examine the stability of time dependent flows - specifically, the relationship between transient growth of perturbations to the time mean flow and the emergence of the first Lyapunov mode and the role of non-normality in supporting both the short time error growth and the asymptotic Lyapunov modes. ***