The Role of Unbalanced Motion in the Upper Troposphere and Stratosphere

对流层上部和平流层不平衡运动的作用

• 批准号: 9903514
• 负责人: Timothy Dunkerton
• 金额: $ 23.83万
• 依托单位: NorthWest Research Associates, Incorporated
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9903514&HistoricalAwards=false
• 关键词: Role; Unbalanced; Motion; Upper; Troposphere

9903514Dunkerton, NWRA"The Role of Unbalanced Motion in the Upper Troposphere and Stratosphere" The unbalanced component of motion - consisting of gravity waves, inertial instabilities and forced circulations - is essential to the evolution of large-scale balanced flow in the atmosphere. The principal investigator and colleagues will examine several aspects of unbalanced dynamics relevant to the tropical troposphere, stratosphere, and mesosphere as well as the extratropical upper troposphere and stratosphere in an attempt to understand how these unbalanced motions are produced. The PI will examine:(1) the stability of the near-equatorial Rossby-wave critical layer to unbalanced flow instabilities, including inertial and divergent barotropic instability. Local instabilities occur as planetary Rossby waves from midlatitudes draw anomalous potential vorticity (PV) into the winter hemisphere while setting up a reversed meridional gradient of PV. The structure and growth rate of local instabilities will be explored for realistic distributions of potential vorticity.(2) the role of gravity waves in the quasi-biennial and semiannual oscillations. The PI will use a new parameterization for gravity wave induced force for this study, and a diagnostic measure of gravity wave momentum flux in mean vertical shear will be extended to equatorially trapped modes. (3) the effect of body forces on the Hadley circulations. (4) the excitation of inertia-gravity waves (IGWs) in an idealized baroclinic lifecycle using a numerical model in which type of baroclinic instability is varied over a wider range of lifecycles. (5) the nature of observed shallow disturbances near the jetstream. Observations from the Middle and Upper Atmosphere (MU) radar and Japanese rawinsonde observations of velocity layers will be analyzed in a collaborative study with Dr. Kaoru Sato of Kyoto University. (6) the role of inertia-gravity waves in transport near the tropopause. This also will be done in collaboration with Dr. Sato and will use simulations from a high-resolution general circulation model.

运动的不平衡成分--由重力波、惯性不稳定和强迫环流组成--对大气中大尺度平衡流动的演变至关重要。首席研究员及其同事将研究与热带对流层、平流层和中间层以及温带上层对流层和平流层有关的不平衡动力学的几个方面，试图了解这些不平衡运动是如何产生的。PI将检验：(1)近赤道Rossby波临界层对不平衡流动不稳定的稳定性，包括惯性和辐散正压不稳定。局地不稳定是由于来自中纬度的行星Rossby波将反常位涡(PV)吸引到冬半球，同时建立了反转的经向位涡梯度。对于位涡的真实分布，我们将探索局地不稳定的结构和增长速率。(2)重力波在准两年和半年振荡中的作用。在本研究中，PI将使用一种新的重力波诱发力的参数，并将平均垂直切变中的重力波动量通量的诊断量度推广到赤道俘获模式。(3)体力对Hadley环流的影响。(4)利用斜压不稳定类型在较宽的生命周期范围内变化的数值模式，在理想的斜压生命周期中激发惯性重力波。(5)在急流附近观测到的浅层扰动的性质。来自中高层大气(MU)雷达的观测和日本测速探空仪对速度层的观测将在与京都大学佐藤佳博士的合作研究中进行分析。(6)惯性重力波在对流层顶附近输送中的作用。这也将与佐藤博士合作完成，并将使用高分辨率大气环流模型的模拟。