SGER: A Search for a Hot Oxygen Corona Using High Spectral Resolution OII 732 nm Measurements

该项目评估了非热O和O+原子群体普遍存在于高层大气和上层电离层的命题。这种“热氧”群体在文献中是通过从可见光和紫外线暮光气辉发射中得出的[O]和[O+]尺度高度，以及通过测量O+732.0纳米光谱特征的热线宽度来识别的。该项目的目的是通过比较光学和雷达测量结果，实现对中纬度O+温度的直接评估。这些任务包括：(1)从2003年5月在阿雷西博天文台进行的高光谱分辨率732.0 nm测量中推导出O+温度，(2)利用阿雷西博非相干散射雷达技术获取一组新的732.0 nm数据，以同时测量O+温度，以及(3)回顾以前的7320 nm线形数据。对2003年5月的数据的初步分析，要求对混合双线光谱特征进行处理，根据轮廓宽度，没有显示出显著的热O+群体。然而，新的天文数据表明，双星分裂比以前的研究确定的要大得多，因此有必要对混合双星的温度进行新的分析。这项研究涉及2003年初秋利用阿雷西博天文台的集群式仪器进行的一次观测活动，以同时测量黄昏期间大气层外732.0 nm发射、大气层外630.0 nm发射和高空656.3 nm发射的多普勒轮廓。在这项实验中，将在天顶和海拔75度之间同时获得O+温度的ISR测量。因此，观测将使用三个法布里-珀罗涉仪(FPI)、两个光度计、一个全天成像仪和非相干散射雷达(ISR)。结果应提供四项独立的温度测量：一项来自F2电离层峰值下方(来自OI 630.0 nm剖面)，两项来自电离层顶部阴影终止点附近(来自HI 656.3 nm和OII 732.0 nm剖面)，以及一项来自ISR技术。这项研究广泛地影响了其他实验和分析技术对高层大气和上层电离层组成的研究。由雷达技术得出的顶部离子成分目前取决于顶部可以忽略不计的热O的假设。这一重要性反过来又影响到空间天气对顶部可靠的H+成分的需求，目前最好是由雷达技术提供。

This project evaluates the proposition that a population of non-thermal O and O+ atoms commonly exists in the upper atmosphere and topside ionosphere. This "hot oxygen" population is identified in the literature by scale heights of [O] and [O+] derived from visible and ultraviolet twilight airglow emissions, and by measuring the thermal line width of the O+ 732.0 nanometer spectral feature. The aim of the project is to achieve a direct evaluation of the O+ temperature at mid-latitude by comparing optical and radar measurements. The tasks include: (1) Derivation of O+ temperature from high spectral resolution 732.0 nm measurements made at the Arecibo Observatory in May, 2003, (2) Acquisition of a new set of 732.0 nm data indexed to simultaneous measurements of O+ temperature using the Arecibo Incoherent Scatter Radar (ISR) technique, and (3) A review of previous 7320 nm line profile data. Preliminary analysis of the May 2003 data, demanding treatment of a mixed doublet spectral feature, do not indicate a significant population of hot O+ based on the profile widths. However, new astronomical data suggest that the doublet splitting is significantly larger than earlier research has determined, and a new analysis of temperature derived from the mixed doublet is necessary. The study involves an observational campaign in the early fall of 2003 using clustered instrumentation at the Arecibo Observatory to simultaneously measure the Doppler profiles of the OII 732.0 nm emission, the OI 630.0 nm emission, and the HI 656.3 nm emission during twilight periods. Simultaneous ISR measurements of the O+ temperature will be obtained between the zenith and 75 degrees elevation during this experiment. The observations will thus employ three Fabry-Perot interferometers (FPI), two photometers, an all sky imager, and the incoherent scatter radar (ISR). The results shall provide four independent measures of temperature: one from just below the F2 ionospheric peak (from the OI 630.0 nm profiles), two from near the shadow terminator in the topside ionosphere (from the HI 656.3 nm and OII 732.0 nm profiles), and one from the ISR technique. This research broadly impacts upper atmospheric and topside ionospheric composition research by other experimental and analytical techniques. The topside ion composition, derived from radar techniques, currently depends upon the assumption of negligible hot O in the topside. The significance in turn impacts the space weather need for reliable H+ composition in the topside, which are currently best supplied by radar techniques.