DOI: 10.1002/2017JA024790
Scopus记录号: 2-s2.0-85047531004
论文题名: Evidence for Radiative Recombination of O+ Ions as a Significant Source of O 844.6 nm Emission Excitation
作者: Waldrop L. ; Kerr R.B. ; Huang Y.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 4 起始页码: 3078
结束页码: 3086
语种: 英语
英文关键词: airglow photochemistry
; radiative recombination
英文摘要: Photoelectron (PE) impact on ground-state O(3P) atoms is well known as a major source of twilight 844.6 nm emission in the midlatitude thermosphere. Knowledge of the PE flux can be used to infer thermospheric oxygen density, [O], from photometric measurements of 844.6 nm airglow, provided that PE impact is the dominant process generating the observed emission. During several spring observational campaigns at Arecibo Observatory, however, we have observed significant 844.6 nm emission throughout the night, which is unlikely to arise from PE impact excitation which requires solar illumination of either the local or geomagnetically conjugate thermosphere. Here we show that radiative recombination (RR) of O+ ions is likely responsible for the observed nighttime emission, based on model predictions of electron and O+ ion density and temperature by the Incoherent Scatter Radar Ionosphere Model. The calculated emission brightness produced by O + RR exhibits good agreement with the airglow data, in that both decay approximately monotonically throughout the night at similar rates. We conclude that the conventional assumption of a pure PE impact source is most likely to be invalid during dusk twilight, when RR-generated emission is most significant. Estimation of [O] from measurements of 844.6 nm emission demands isolation of the PE impact source via coincident estimation of the RR source, and the effective cross section for RR-generated emission is found here to be consistent with optically thin conditions. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114123
Appears in Collections: 气候减缓与适应
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作者单位: Department of Electrical and Computer Engineering, University of Illinois at Urbana–Champaign, Urbana, IL, United States; Computational Physics, Inc., Chelmsford, MA, United States
Recommended Citation:
Waldrop L.,Kerr R.B.,Huang Y.. Evidence for Radiative Recombination of O+ Ions as a Significant Source of O 844.6 nm Emission Excitation[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(4)