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

合作研究：CEDAR——南半球准两天波的生命周期

• 批准号: 1552255
• 负责人: David Ortland
• 金额: $ 7.49万
• 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: 2016
• 资助国家: 美国
• 起止时间: 2016-03-15 至 2019-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1552255&HistoricalAwards=false
• 关键词: Collaborative; Research; CEDAR; Life; Cycle

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.

大气区域耦合、能量学和动力学（CEDAR）计划是一个基础广泛、社区指导的高层大气研究计划，旨在了解从低层大气向上通过电离层上层大气的大气区域行为。该方案的主要主题之一是测量大气波活动从低层大气层向中间层和低热层的转移，后者与低电离层重叠。与这种波耦合相关的一个重要动力学现象称为准两日波（QTDW），这是在中层大气风和温度中看到的大尺度波结构，在南半球区域特别明显，空间范围超过数千公里。这种结构的寿命在一到两周之间变化，具有尚不清楚的快速生长，进化和衰变曲线。该奖项的研究将利用来自美国航天局两颗卫星的同步数据，以高时间分辨率跟踪该结构的空间发展。该数据库的10年范围将使这种现象能够每年进行相互比较，并在太阳活动最大和最小两个时期进行比较。 这项研究将通过应用理论原始方程模型来确定产生这种波浪结构的主要激发源。两名可能的候选人将接受调查。一种（斜压不稳定）是平流层急流极向边缘激发的动力不稳定机制的发展。另一种（惯性不稳定性）是由于科里奥利力非常微弱而在地理赤道附近激发的不稳定过程。 这个奖项的更广泛的影响是我们对基本MLT动态的整体理解的提高。研究生将获得半时间的支持。拟议的活动将直接解决有关大气高度区域之间的耦合问题，以及QTDW波现象和纬向平均环流之间可能的能量反馈。将从生成区域到110 km区域对QTDW结构进行整体研究。我们将研究平流层顶和中层顶边界的动量和能量交换。这项研究将包括2002年至今的十年观察，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。