Collaborative Research: CEDAR--A Novel Technique for Estimating Oxygen Density in the Mid-Latitude Thermosphere

合作研究：CEDAR——一种估算中纬度热层氧密度的新技术

• 批准号: 0836489
• 负责人: Lara Waldrop
• 金额: $ 16.75万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0836489&HistoricalAwards=false
• 关键词: Collaborative; Research; CEDAR; Novel; Technique

This project aims to develop an accurate technique for determining the atomic oxygen density in the mid-latitude thermosphere by combining modern instrumentation with state of the art modeling. The method will combine optical and radar measurements to constrain a forward model of a key thermospheric O-atom emission, the twilight airglow at 8446 A, and in turn use the constrained model to develop an [O] estimation scheme suitable for application at other mid-latitude locations. The 8446 A emission has long been considered an ideal candidate for [O] remote sensing owing to its relatively simple emission model, and the project will acquire an unprecedented set of 8446 A spectral data under various observational conditions at two distinct mid-latitude facilities: Millstone Hill (MH) Observatory in Massachusetts and Arecibo Observatory (AO) in Puerto Rico. Additional parameters derived from nested incoherent scatter radar, Fabry-Perot interferometer, and photometer measurements will not only serve as additional forward model constraints, but also help assess the validity of current model assumptions, specifically with regard to the role of secondary sources of 8446 A production. Together with a thorough quantification of model parameter dependencies, the constrained forward model will be used to develop a novel inverse-theoretical technique to estimate thermospheric [O] from measured 8446 A brightness at mid-latitudes. Quantification of neutral atomic oxygen, the dominant constituent in the Earth's thermosphere between 200 - 600 km, is important for several reasons. In this region, its resonant charge exchange with O+, the principle ion in the F-region ionosphere, plays a vital role in both the momentum and energy exchange between the thermosphere and ionosphere. Similarly, its charge exchange with H+ has long been recognized as an important influence on ion transport between the ionosphere and plasmasphere. Owing to this strong chemical coupling, the accuracy of many fundamental aeronomical calculations -- such as the derivation of transport coefficients, neutral wind speeds, energy deposition rates, chemical reaction rates, or photochemical emission brightnesses -- hinges on accurate specification of [O]. Thus, current uncertainties in thermospheric composition and density limit the understanding of the coupled thermosphere-ionosphere system, both with regard to its climatological variability as well as its response to impulsive forcing from above and below. The development of a new, ground-based capability of measuring thermospheric [O] will benefit both of these central priorities of the NSF CEDAR program. One graduate student will be trained in this Aeronomy-related area with support from the project. The student will gain familiarity with acquisition and analysis of ISR spectra as well as that of optical SHS, FPI, and photometer data. Available internal funds for undergraduate research support, together with the strong involvement of AO in the Research Experiences for Undergraduates (REU) program, presents another opportunity to introduce undergraduate students to aeronomy as well.

该项目旨在开发一种准确的技术，用于通过将现代仪器与最先进的建模结合使用，以确定中纬度热层中的原子氧密度。该方法将结合光学测量和雷达测量，以约束关键热层O-ATOM发射的正向模型，在8446 A处的暮光气球，然后使用约束模型开发适用于其他中纬度位置应用的[O]估计方案。由于其相对简单的发射模型，8446 A排放长期以来一直被认为是[O]遥感的理想候选者，并且该项目将在两个不同的中间层次设施下在各种观测设施下获得前所未有的8446 A频谱数据：MASSACHUSETTS和ARECIBO和ARECIBO PARTORITATION（MH）观察山（MH）观测（MH）观察（MH）。源自嵌套不连贯的散点雷达，Fabry-Perot干涉仪和光度计测量值的其他参数不仅将作为额外的前向模型约束，而且还有助于评估当前模型假设的有效性，特别是关于8446 A生产的次级来源的作用。加上模型参数依赖性的彻底量化，受约束的正向模型将用于开发一种新型的逆理论技术，以估算从测量的8446 A中的亮度估算热层[O]。中性原子氧的定量，即200-600 km之间地球热圈中的主要成分，这对于多种原因很重要。在该区域，其与O+的共振电荷交换（F区域层中的原理离子）在热层和电离层之间的动量和能量交换中起着至关重要的作用。同样，它与H+的电荷交换长期以来一直被认为是对电离层和等离子间之间离子转运的重要影响。由于这种强大的化学耦合，许多基本的空气计算的准确性 - 例如传输系数的推导，中性风速，能量沉积速率，化学反应速率或光化学发射亮度 - 在[O]的准确规范上取决于[O]。因此，在热圈组成和密度中的当前不确定性限制了对热层 - 离子层系统的理解，这既取决于其气候变异性，又是其对冲动强迫的响应。开发一种新的，基于地面的测量热层[O]的能力将使NSF Cedar计划的这两个中心优先级受益。一名研究生将在该项目的支持下在该航空相关地区接受培训。学生将熟悉ISR光谱的采集和分析以及光学SHS，FPI和光度计数据的熟悉。可用的内部资金用于本科研究支持，以及AO在本科生（REU）计划的研究经验中的强烈参与，还有另一个机会将本科生介绍给航空通道。