Thermospheric Composition and Solar EUV Flux from the Global-scale Observations of the Limb and Disk (GOLD) mission | CU Experts

Observations of far-ultraviolet (FUV) dayglow by the Global-scale; Observations of Limb and Disk (GOLD); mission provide a new opportunity to monitor relative composition; changes in the upper atmosphere as well as; solar extreme ultraviolet (EUV) variability. Relative composition; changes are measured through ΣO/N,; which is the column density ratio of atomic oxygen to molecular; nitrogen, while Q provides; a measure of the solar EUV energy flux below 45 nm into the upper; atmosphere. This; spectral range provides the ionizing radiation which ultimately results; in FUV airglow emission; produced by photodissociation and photoelectron impact. The quantities; ΣO/N and; Q are derived from GOLD FUV observations through lookup tables that are; constructed using a first-principles photoelectron; transport model. The two FUV emission features used are O I 135.6 nm and; N Lyman-Birge-Hopfield; (LBH) bands as functions of solar zenith angle. We present an overview; of the theoretical basis for the; algorithms and practical considerations for application to GOLD data.; The effect on derived products; from uncertainties in electron impact cross sections, off-nadir viewing,; and instrument artifacts are; reviewed. We also discuss GOLD Level 1C DAY and Level 2 ON2 and QEUV; data products and present; representative samples of each.

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