The Role of Unbalanced Motion in the Upper Troposphere and Stratosphere

dunkerton， NWRA“对流层上层和平流层中不平衡运动的作用”运动的不平衡成分——由重力波、惯性不稳定性和强迫环流组成——对大气中大规模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、中间层以及温带对流层上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将研究：(1)近赤道罗斯比波临界层对不平衡流动不稳定性的稳定性，包括惯性和发散正压不稳定性。来自中纬度的行星罗斯比波将异常位涡（PV）带入冬季半球，同时建立了一个反向的PV经向梯度，从而导致局地不稳定。为了得到真实的位涡分布，我们将探讨局部不稳定性的结构和增长速度。(2)重力波在准两年和半年振荡中的作用。在本研究中，PI将采用一种新的重力波诱导力参数化方法，并将平均垂直切变中重力波动量通量的诊断方法扩展到赤道捕获模式。(3)机体力对哈德利环流的影响。(4)利用斜压不稳定性在较宽的生命周期范围内变化的数值模型，研究理想斜压生命周期中惯性-重力波的激发。(5)观测到的急流附近浅层扰动的性质。在与京都大学Kaoru Sato博士的合作研究中，将分析中高层大气（MU）雷达和日本雷达对速度层的观测结果。(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，并将使用高分辨率一般循环模型的模拟。

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.