Mesosphere and Lower Thermosphere Dynamics Studies Employing the Southern Argentina Agile MEteor Radar (SAAMER), Correlative Measurements, and Modeling

利用阿根廷南部敏捷流星雷达 (SAAMER) 进行中层和低层热层动力学研究、相关测量和建模

• 批准号: 2131350
• 负责人: David Fritts
• 金额: $ 76.8万
• 依托单位: GLOBAL ATMOSPHERIC TECHNOLOGIES AND SCIENCES, INC.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2131350&HistoricalAwards=false
• 关键词: Mesosphere; Lower; Thermosphere; Dynamics; Studies

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). This award supports the continued operations of a suite of instruments including the SAAMER meteor radar at the southern tip of South America known as Terra del Fuego. The award will support the continued study of large- and small-scale dynamics that play many roles in the mesosphere and lower thermosphere (MLT). Tides and planetary waves (PWs) account for the major variability on larger horizontal and vertical scales because they propagate largely without strong attenuation from sources in the troposphere and stratosphere into the MLT and above. These have been studied using MLT radar, lidar, and satellite measurements for many years, and they account for the major large-scale variability of the MLT. Smaller-scale gravity waves (GWs) arise from multiple sources modulated by tropospheric weather, especially mountain waves (MWs), convective GWs, inertia-GWs, and secondary GW (SGW) generation where GWs from other sources attain large amplitudes. Most of these dynamics have been studied extensively, both observationally and via modeling, but the smaller scales, and their large range of dynamics, interactions, and instabilities have prevented a quantitative understanding of their dynamics and influences to date. The importance of these large- and small-scale dynamics derives from their major influences in the MLT and extending to lower and higher altitudes. Observations and analyses of large- and small-scale dynamics play central roles in identifying and understanding the diverse processes that determine the structure and variability of the atmosphere. Such efforts are especially needed in the MLT, where the dynamics are driven by energy and momentum fluxes due to GW propagation from sources at lower altitudes that vary strongly with tropospheric weather. MLT responses are often strongly nonlinear due to large GW amplitude increases leading to instabilities, turbulence, and forcing of mean and large-scale wave motions that are poorly understood at present. Analyses of observations by Aura MLS and MLT radars will quantify key PW and tidal dynamics. Observational guidance of GW responses at TdF and NAVGEM re-analyses would aid the detailed modeling addressing MW and more general GW dynamics, instabilities, forcing, and responses in the MLT. A Univ. of Colorado (CU) graduate student would receive training in state-of-the-art GW, KHI, and geophysical turbulence modeling and supercomputing. The collection, formatting, and provision of global MLT radar data for NAVGEM data assimilation would also be a significant benefit for the CEDAR community. The major larger-scale forcing and smaller-scale forcing and variability of the MLT is driven by GWs that account for the major vertical fluxes of horizontal momentum driving MLT dynamics where GW breaking and dissipation cause energy and momentum deposition. These lead to local flow accelerations, mixing, feedbacks on the larger-scale dynamics contributing to GW breaking, and induced residual circulations having impacts at lower altitudes. All these dynamics have been assessed to varying degrees in previous observational and/or modeling studies. The new award would study different processes that include the following: 1)effects of GW/tidal interactions on tidal amplitudes & phases and GWs at higher altitudes, 2) influences of intermittency in GW breaking, energy & momentum deposition, and mixing, 3) influences of large-scale Kelvin-Helmholtz instabilities (KHI) in GW & tidal shears, 4) sources and effects of GW “self-acceleration” dynamics, for which there is significant modeling & observational support, but the implications of which are largely unknown, and 5) influences on MLT structure and variability by transient PWs arising at lower altitudes. Initial conditions for these models would be provided by NAVGEM re-analyses extending to 140 km based on global MLT radar winds supporting the NAVGEM data assimilation efforts coordinated by GATS personnel.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。该奖项支持一套仪器的持续运行，包括位于南美洲南端的SAAMER流星雷达，称为Terra del Fuego。该奖项将支持继续研究在中间层和低热层（MLT）中发挥许多作用的大尺度和小尺度动力学。潮汐和行星波（PW）占较大的水平和垂直尺度上的主要变化，因为它们传播很大程度上没有强烈的衰减，从对流层和平流层的源到MLT及以上。这些已经使用MLT雷达，激光雷达和卫星测量进行了多年的研究，它们解释了MLT的主要大尺度变化。小尺度重力波（GWs）产生于受对流层天气调制的多个源，特别是山波（MW）、对流GWs、惯性GWs和次级GWs（SGW）生成，其中来自其他源的GWs获得大振幅。这些动力学中的大多数已经被广泛研究，无论是观测还是通过建模，但是较小的尺度，以及它们的大范围动力学，相互作用和不稳定性，阻碍了对它们的动力学和影响的定量理解。这些大尺度和小尺度动力学的重要性来自于它们在MLT中的主要影响，并延伸到较低和较高的海拔。对大、小尺度动态的观测和分析在确定和了解决定大气结构和变化的各种过程方面发挥着核心作用。在MLT中尤其需要这样的努力，其中动力学是由能量和动量通量驱动的，这是由于GW从较低高度的源传播而引起的，这些源随对流层天气变化很大。MLT响应往往是强烈的非线性，由于大GW振幅增加导致不稳定性，湍流，并迫使平均和大尺度的波动，目前知之甚少。Aura MLS和MLT雷达的观测分析将量化关键的PW和潮汐动力学。在TdF和NAVGEM再分析时GW响应的观测指导将有助于详细建模，解决MW和更一般的GW动态，不稳定性，强迫和MLT中的响应。一名科罗拉多大学（CU）的研究生将接受最先进的GW、KHI和地球物理湍流建模和超级计算方面的培训。为NAVGEM数据同化收集、格式化和提供全球MLT雷达数据也将给CEDAR界带来重大好处。MLT的主要大尺度强迫和小尺度强迫和变率是由GW驱动的，GW占水平动量驱动MLT动力学的主要垂直通量，GW断裂和耗散导致能量和动量沉积。这些导致当地的流动加速，混合，反馈的大尺度动力学的GW打破，并在较低的高度产生影响的剩余环流。所有这些动力学在以前的观察和/或建模研究中进行了不同程度的评估。新的奖项将研究不同的过程，包括以下内容：1）GW/潮汐相互作用对潮汐振幅相位和更高高度的GW的影响，2）GW断裂，能量动量沉积和混合中的不稳定性的影响，3）大规模开尔文-亥姆霍兹不稳定性（KHI）在GW潮汐剪切中的影响，4）GW“自加速”动力学的来源和影响，对此有重要的模拟观测支持，但其含义在很大程度上是未知的，以及5）在较低高度产生的瞬态PWs对MLT结构和可变性的影响。这些模型的初始条件将由NAVGEM再分析提供，该分析基于全球MLT雷达风，延伸至140 km，支持GATS人员协调的NAVGEM数据同化工作。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。