Internal Generation of Low and Ultra-Low Frequency Variability in the Atmosphere

这个项目将研究大气内部在月、季和年的时间尺度上产生变化的动力学机制。重点将放在定位和理解低频率和释放大气可用能量的较短时间尺度之间的反馈。这些研究将在简单的两层原始方程模式和现有的NCAR社区气候模式的长期运行的背景下进行。拟议的工作包括以下具体研究：1)研究两级模式中的“指数循环”，以确定其动力学及其对定常涡旋的影响。2)研究两层模式中内部变率和外部(热带加热)变率之间的相互作用；3)对CCM的扩展模拟进行诊断分析，以确定在两层模式中产生低频变率的动力机制模型在更真实的模型中是相关的。4)分析了CCM中Rossby波源的低频变率及其与低频特征天气强迫的相互作用。5)研究两层模式在行星空间尺度上发现的季节间和长时间尺度变化的动力学。这项研究之所以重要，是因为它寻求改善对人类活动具有重要意义的时间尺度上造成气候变化的过程的理解。

This project will study the dynamical mechanisms by which the atmosphere can internally generate variability on timescales of months, seasons, and years. The focus will be on locating and understanding the feedbacks between the low frequencies and the shorter timescales at which the available energy of the atmosphere is released. These investigations will be carried out in the context of simple two-level primitive equation model and existing long runs of the NCAR Community Climate Model. The proposed work comprises the following specific studies: 1) Studies of the "index cycle in the two-level model to determine its dynamics and its effects on stationary eddies. 2) Studies of the interactions between internal variability and externally generated (by tropical heating) variability in the two-level model 3) Diagnostic analyses of extended simulations of the CCM to see if the dynamical mechanisms that generate low-frequency variability in the two-level model are relevant in a more realistic model. 4) Analysis of the low-frequency variability of the Rossby wave source in the CCM and its interaction with synoptic forcign of low-frequency features. 5) Studies of the dynamics of the inter-seasonal and longer timescale variability that is found at planetary spatial scales in the two-level model. This research is important because its seeks to improve understanding of the processes responsible for climate variations on time scales of great importance to human activities.