CEDAR: Observational and Modeling Studies of Thermosphere-Ionosphere Metal (TIMt) Layers over Boulder

随着数以吨计的宇宙尘埃每天落在地球上，金属原子和离子通过流星烧蚀并溅射到高层大气中释放出来，形成了大约75-105公里的永久金属层，人们已经知道这一层已有近一个世纪的历史。2011年在南极洲进行的激光雷达观测揭示了热层-电离层金属(TIMt)层的存在。2021年在博尔德上空的激光雷达观测中首次报道了钠种(Tina)中有规律地出现TIMt层，那里的Tina层几乎每晚都会在黎明之前和黄昏后出现。这个项目将使用模拟和观测来研究Boulder TIMt层，这将为研究空间-大气相互作用区的基本过程打开一扇新的大门。该项目将显著提高我们对金属离子和原子、等离子体-中性耦合以及中纬度热层潮汐的理解。这些认识的提高将有助于推进空间气象研究。该奖项将支持参与该项目的研究生和本科生。该团队将开展推广活动，如制作YouTube视频和为K-12组织科学实地考察，以激励科学领域的年轻一代。该项目将使用观测和建模方法来解决以下关键科学问题：1)黎明前经常出现在博尔德等中纬度地区的Tina层的形成机制是什么？中性风、电离层电场、重力、扩散、流星烧蚀和化学作用在TIMT的形成和演化中起什么作用？2)TIMT层如何被用来帮助描述/验证由CTMT和ICON(电离层连接探测器)提供的100-200公里热层间隙区域的潮汐风？3)在中纬度离子传输中，哪种传输起主要作用--区域传输还是全球传输？等离子体不稳定性是否通过影响电场来影响TIMT层？取自南极洲TIFE模型的区域TIMT模型将被修改用于北部中纬度地区，以研究Boulder Tina层以及离子传输。该团队将对激光雷达数据进行深入分析，并敲定初步观测结果。他们将把黎明前的天娜相位、体积混合比及其变化与各种模型或测量(例如CTMT、ICON、HWM、由ICON驱动的TIEGCM和SD-WACCM-X+DART)提供的中性风(潮汐风和平均风)的变化进行比较，与由模型或测量(例如TIEGCM、Millstone Hill测量)提供的北中纬度电场的变化进行比较，并与流星输入通量(MIF)的变化进行比较，以帮助解释观测结果。比较结果将指导项目后期驱动TIMT模型的输入参数的选择。根据该项目开发的一个新的区域TIMT模型将有助于量化对各种因素对个人贡献的理解。它将成为在激光雷达观测不断增加的世界中进行研究的强大工具。从该项目中获得的区域垂直输送和化学方面的新知识将有助于未来大气环流模式的发展。该团队还将开展几项重要的外展和多元化活动：招募和培训一名女本科生、YouTube视频、科学实地考察和新闻发布会。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With tons of cosmic dust falling on Earth every day, metal atoms and ions are released via meteor ablation and sputtering into the upper atmosphere, forming permanent metal layers (~75–105 km) that have been known for nearly a century. Recent lidar observations in Antarctica in 2011 have revealed the existence of thermosphere-ionosphere metal (TIMt) layers. Regular occurrence of TIMt layers in Na species (TINa) was reported for the first time from lidar observations in 2021 over Boulder, where TINa layers occur before dawn and after dusk nearly every night. This project will use modeling and observations to investigate Boulder TIMt layers that open a new door to study the fundamental processes in the space-atmosphere interaction region. The project will significantly enhance our understanding of metallic ions and atoms, plasma-neutral coupling, and thermospheric tides at mid-latitudes. The enhanced understandings will help advance space weather research. This award will support graduate and undergraduate students involved in this project. The team will conduct outreach activities such as making YouTube videos and organizing science field trips for K-12 to inspire the younger generation in science.This project will use observations and modeling approach to address the following key science questions:1) What are the formation mechanisms for the pre-dawn TINa layers with regular occurrence over midlatitudes like Boulder? What roles do neutral winds, ionospheric electric fields, gravity, diffusion, meteor ablation, and chemistry play in the TIMt formation and evolution?2) How can TIMt layers be used to help delineate/validate tidal winds, provided by CTMT and ICON (Ionospheric Connection Explorer), in the thermospheric gap region of 100-200 km?3) Which transport plays the major role in ion transport at midlatitudes—regional or global transport? Does plasma instability affect TIMt layers via impacting electric fields?A regional TIMt model, adopted from an Antarctica TIFe model, will be modified for the northern midlatitudes to study the Boulder TINa layers as well as ion transport. The team will carry out in-depth analyses of lidar data and finalize the preliminary observational results. They will compare the pre-dawn TINa phases, volume mixing ratios, and their variations with those of neutral winds (tidal winds and mean winds) provided by various models or measurements (e.g., CTMT, ICON, HWM, TIEGCM-driven by ICON, and SD-WACCM-X + DART), with those of electric fields at northern midlatitudes provided by models or measurements (e.g., TIEGCM, Millstone Hill measurements), and with those of meteor input flux (MIF), to help interpret the observations. The comparison results will guide the selection of input parameters to drive the TIMt model in later years of the project. A new regional TIMt model developed from this project will be instrumental in quantifying the understanding of individual contributions from various factors. It will become a powerful tool for studies in a world of ever-increasing lidar observations. The new knowledge gained from this project about the regional & vertical transport and chemistry will assist the future development of general circulation models. The team will also conduct several major outreach and diversity activities: Recruit and train one female undergraduate student, YouTube videos, science field trips, and press releases.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.