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

该项目评估了在上层大气和上层电离层中普遍存在非热O和O+原子的命题。这种“热氧”种群在文献中通过由可见光和紫外线微光气辉发射得出的[O]和[O+]的尺度高度，以及通过测量O+ 732.0纳米光谱特征的热谱线宽度来确定。该项目的目的是通过比较光学和雷达测量，实现对中纬度O+温度的直接评估。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O+温度；(2)利用阿雷西博非相干散射雷达（ISR）技术获取一组新的732.0 nm数据，与O+温度同时测量相关联；(3)回顾以前的7320 nm线剖面数据。对2003年5月数据的初步分析，要求对混合双重光谱特征进行处理，根据剖面宽度，没有显示出热O+的显著种群。然而，新的天文数据表明，双重子分裂比早期研究确定的要大得多，因此有必要对混合双重子的温度进行新的分析。这项研究包括2003年初秋在阿雷西博天文台的一次观测活动，使用集群仪器同时测量黄昏期间OI 732.0 nm发射，OI 630.0 nm发射和HI 656.3 nm发射的多普勒谱。同时ISR测量O+温度之间的天顶和75度的高度在这个实验中获得。因此，观测将使用三个法布里-珀罗干涉仪（FPI），两个光度计，一个全天成像仪和非相干散射雷达（ISR）。结果将提供四个独立的温度测量：一个来自F2电离层峰值以下（来自OI 630.0 nm剖面），两个来自上层电离层阴影终结者附近（来自HI 656.3 nm和OI 732.0 nm剖面），一个来自ISR技术。这项研究广泛影响了其他实验和分析技术对上层大气和上层电离层成分的研究。由雷达技术得出的上层甲板离子组成目前依赖于假设上层甲板的热氧可以忽略不计。这一意义反过来又影响了空间天气对上层可靠H+组成的需求，目前最好的是由雷达技术提供。

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.