Estimation of Thermospheric Oxygen Density and Temperature From Combined Optical and Radar Measurements

中性原子氧（O）是地球高层大气中的一个关键物种，在200-700 km之间的热层组成中占主导地位。航天器在低地球轨道运行、了解热层和电离层之间的耦合以及描述大气层对空间天气或气候变化等驱动因素的动态响应，都需要了解其密度[O]。本计画系发展一种新的技术，以非相干散射雷达（ISR）资料及符合的光学辐射观测资料为基础，来估算[O]。新技术将提供550-850公里高度范围内的O密度和温度估计值。它基于O和H+而不是O和O+耦合的[O]估计，从而避免了与过去困扰传统地基技术的O+-O碰撞截面中的不确定性相关的困难。这是可能的新的非相干散射多离子拟合技术最近在阿雷西博开发的顶侧电离层。这项技术将应用于阿雷西博天文台近20年的光学和雷达数据，以编制中纬度[O]和热层温度变化的气候学。有助于提高阿雷西博光学探测器灵敏度和双波束雷达能力的新测量将用于将中性密度反演的高度范围向下扩展到较低的高度。这将允许一个独立的，大大改善了所谓的“伯恩赛德因子”，F，O+-O碰撞频率的理论和经验估计之间的差异的措施估计。在热层化学中，对这一因素的现有估计存在很大差异，这是一个长期存在的难题。该项目的更广泛影响包括这种新技术对广泛的其他大气研究的有用性。此外，该项目还包括为学生提供研究机会，并将有助于促进一名年轻、成功的女科学家的独立研究事业。

Neutral atomic oxygen, O, is a key species in Earth's upper atmosphere, where it dominates thermospheric composition between ~200-700 km. Knowledge of its density, [O], is required for spacecraft operations in low earth orbit, for understanding the coupling between the thermosphere and ionosphere, and for characterizing the dynamic atmospheric response to drivers such as space weather or climate change. This project is to develop a new technique for [O] estimation based on Incoherent Scatter Radar (ISR) data and coincident optical emission observations. The new technique will provide both O density and temperature estimates over the altitude range 550-850 km. It bases the [O] estimation on O and H+ rather than O and O+ coupling, thereby avoiding the difficulties associated with uncertainties in the O+-O collisional cross section that have plagued traditional ground-based techniques in the past. This is made possible by new incoherent scatter multi-ion fitting techniques recently developed at Arecibo for the topside ionosphere. The technique will be applied to nearly 20 years of optical and radar data available from the Arecibo observatory to compile a climatology of mid-latitude [O] and temperature variations for the thermosphere. New measurements facilitating improvements in optical detector sensitivity and dual-beam radar capability at Arecibo will be used to extend the altitude range of the neutral density inversions down to lower altitudes. This will allow for an independent, much improved estimation of the so-called "Burnside factor", F, a measure of the discrepancy between theoretical and empirical estimates for the O+-O collision frequency. The large discrepancies in existing estimates of this factor constitute a long-standing puzzle in thermosphere chemistry. Broader impacts of this project include the usefulness of this new technique for a wide range of other atmospheric studies. In addition, the project includes research opportunities for students and would help further the independent research career of a young, successful female scientist.