CEDAR Postdoc: Numerical Modeling of Mesospheric Bores, Nonlinear Ducted Waves, and Interpretation of Observations in the Middle Atmosphere

该项目是根据2009年美国复苏和再投资法案（公法111-5）资助的。这些波特征发生在中层上层和下层热层，并被确定为一个水平范围大（约500公里）的尖锐波锋，随后是一列波峰。中间层孔是在1993年首次观测到的。从那时起，有许多额外的观察，但详细的了解有限。该项目将定量评估中间层孔的动态和特征，包括支持它们的环境、产生它们的强迫以及它们对大气的影响。这项工作有两个主要组成部分：(1)扩展目前已经开发的数值模式，使其包括更复杂的强迫和典型的中间层和低层热层环境；(2)模式观测的气辉数据，其中激光雷达和雷达同步测量描述了热环境和风环境。对于任务1，提出的模型扩展将模拟更真实的钻孔背景条件以及各种类型的钻孔结构对这些条件的响应。第二个任务将使用气辉、雷达和激光雷达观测来提供有关大气背景热结构和钻孔如何通过它传播的信息。数值研究将提高对钻孔动力学的定量理解，并确定如何扩展或修正现有理论以应用于实际环境。对观测的应用还将定义观测如何最好地量化钻孔动力学以及相关的导管现象。该项目的更广泛影响涉及更好地理解和量化中间层和低层热层的能量和动量输送和沉积，这将影响平均流量和全球环流模式。提高对中间层孔非线性动力学的理解也与其他类似的动态现象有关，无论是在低层大气中还是在各种工程应用中。该项目将支持一名新研究员完成博士学位后的第一次研究工作。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)This project focuses on modeling studies of mesospheric bores. These wave features occur in the upper mesosphere and lower thermosphere and are identified as a sharp wave front with a large horizontal extent (on the order of 500 km) followed by a train of wave crests. Mesospheric bores were first observed in 1993. Since then, there have been many additional observations but limited detailed understanding. This project will quantitatively assess the dynamics and characteristics of mesospheric bores, including the environments that support them, the forcings that give rise to them, and their impacts on the atmosphere. The effort has two main components: (1) extend a current numerical model already developed to encompass more complicated forcings and environments typical of the mesosphere and lower thermosphere; (2) model observed airglow data for which concurrent lidar and radar measurements describe the thermal and wind environments. For task 1, the proposed model extensions will simulate more realistic background conditions for the bores along with the responses of various types of bore structures to these conditions. The second task will use airglow, radar, and lidar observations to provide information on the background thermal structure of the atmosphere and on how bores propagate through it. The numerical studies will improve quantitative understanding of bore dynamics and determine how the existing theories might be expanded or amended to apply in realistic environments. Applications to observations will also define how observations can best quantify the bore dynamics as well as related ducting phenomena. The broader impacts of the project concern the implications for better understanding and quantification of energy and momentum transport and deposition in the mesosphere and lower thermosphere, which impacts the mean flow and global circulation models. An improved understanding of the nonlinear dynamics of mesospheric bores is also relevant to other dynamically similar phenomena, both in the lower atmosphere and in various engineering applications. The project will support a new researcher in his first research effort after completion of the Ph.D.