Collaborative Research: CEDAR--Life Cycle of the Quasi Two-Day Wave in the Southern Hemisphere

大气区域耦合、能量和动力学(Cedar)计划是一个基础广泛的、社区指导的高层大气研究计划，旨在了解从低层大气向上到大气电离上层的大气区域的行为。该方案的主要主题之一是测量大气波活动从低层大气向与低电离层重叠的中间层和低热层的转移。与这种波耦合有关的一个重要的动力学现象称为准两天波(QTDW)，它是一种在中层大气风和温度中可见的大尺度波结构，在空间范围超过数千公里的南半球区域内尤为明显。这种结构的寿命在一到两周之间变化，其快速增长、进化和衰变的轮廓尚不清楚。该奖项的研究将利用美国宇航局两颗卫星的同时数据，以高时间分辨率跟踪该结构的空间进程。该数据库的10年范围将使这一现象能够在每年和太阳活动最高和最低两个时期进行相互比较。这项研究将通过一个理论原始方程模型的应用来确定什么可能是产生这种波结构的主要激发源。将对两名可能的候选人进行调查。一个(斜压不稳定)是由平流层急流的极地边缘提供能量的动力不稳定机制的发展。另一种(惯性不稳定)是地理赤道附近由于科里奥利力非常弱而激发的不稳定过程。这一奖项的更广泛影响是提高了我们对基本MLT动态的整体理解。建议的活动将直接涉及大气高度区之间的耦合问题，以及QTDW波现象学和纬向平均环流之间可能的能量反馈。QTDW结构将从发电区到110公里区域进行全面调查。我们将研究平流层顶和中层顶边界上的动量和能量交换。这项研究将包括2002年至今的十年观测，这将使人们能够研究对比年份，例如平流层变暖的可能影响。

The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) program, a broad-based, community-guided, upper atmospheric research program, is aimed at understanding the behavior of atmospheric regions from the lower atmosphere upward through the ionized upper layers of the atmosphere. One of the major themes of this program is the measurement of the transfer of atmospheric wave activity from the lower atmosphere into the mesosphere and lower thermosphere, which overlaps the lower ionosphere. An important dynamical phenomenon associated with this wave coupling is called the quasi two-day wave (QTDW), which is a large-scale wave structure seen in the middle atmosphere winds and temperatures that is particularly pronounced within the southern hemisphere region with a spatial extent over many thousands of km. The lifetime of this structure varies between one and two weeks with a rapid growth, evolution, and decay profile that is not understood. The research of this award would utilize simultaneous data from two NASA satellites to follow the spatial progression of this structure with high temporal resolution. The 10 years extent of the database will allow this phenomenon to be intercompared from year to year and for the two periods of solar maximum and solar minimum. This research would determine through the application of a theoretical primitive equation model what might be the predominant excitation source generating this wave structure. Two possible candidates would be investigated. One (baroclinic instability) is the development of a dynamical instability mechanism energized by the poleward edge of the stratospheric jet stream. The other (inertial instability) is an instability process energized near the geographic equator as a result of the very weak magnitude of the Coriolis force. The broader impact of this award is the improvement of our overall understanding of fundamental MLT dynamics. A graduate student would receive half-time support.The proposed activity will directly address questions regarding the coupling between atmospheric height regions, and possible energetics feedbacks between the QTDW wave phenomenology and the zonal mean circulation. The QTDW structure will be holistically investigated from the generation region into the 110 km region. Momentum and energy exchange across the stratopause and mesopause boundaries will be examined. The study will encompass a decade of observations, 2002-present, which will allow study of contrasting years, e.g., the possible influence of stratospheric warmings.