The Earth's ultraviolet airglow contains fundamental diagnostic information about the state of its upper atmosphere and ionosphere. Our understanding of the excitation and emission processes which are responsible for the airglow has undergone dramatic evolution from the earliest days of space research through the past several years during which a wealth of new information has been published from high-resolution spectroscopy and imaging experiments. This review of the field begins with an overview of the phenomenology: how the Earth looks in the ultraviolet. Next the basic processes leading to excitation of atomic and molecular energy states are discussed. These concepts are developed from first principles and applied to selected examples of day and night airglow; a detailed review of radiation transport theory is included. This is followed by a comprehensive examination of the current status of knowledge of individual emission features seen in the airglow, in which atomic physics issues as well as relevant atmospheric observations of major and minor neutral and ionic constituents are addressed. The use of airglow features as remote sensing observables is then examined for the purpose of selecting those species most useful as diagnostics of the state of the thermosphere and ionosphere. Imaging of the plasmasphere and magnetosphere is also briefly considered. A summary of upcoming UV remote sensing missions is provided.

Ultraviolet spectroscopy and remote sensing of the upper atmosphere

Simultaneous measurements of disk-viewing OI 135.6 nm and N{sub 2} Lyman-Birge-Hopfield (LBH) dayglow can be used to monitor the solar EUV flux Q{sub EUV} and the column abundance of thermospheric O relative to N{sub 2} (O/N{sub 2}). The authors report on a study that quantifies the relationships between these emissions and the above parameters. Emission is considered from 134.5 to 139.0 nm (designated 135.6 nm) and from 155.0 to 170.0 nm (designated as LBH) at a resolution of 3.6 nm. The intervals and resolution were chosen for analysis of satellite dayglow data to be reported in the companion paper by Evans et al. The first interval is dominated by OI 135.6 nm with minor contributions from LBH 135.4 and 138.3 nm. The second interval contains only LBH. An important finding is that 135.6/LBH is essentially independent of the solar EUV spectrum from low to high activity based on using the Hinteregger formulation for characterizing spectral changes with solar activity. Given this behavior in 135.6/LBH one can then unambiguously interpret changes in this ratio in terms of changes in O/N{sub 2}. Model results show that the relationship between O/N{sub 2} and 135.6/LBH is essentially independent of model atmosphere. Given either 135.6/LBHmore » or O/N{sub 2}, Q{sub EUV} can then be obtained directly from the absolute intensity of either 135.6 nm or LBH.« less

Satellite remote sensing of thermospheric O/N2 and solar EUV: 1. Theory

The analytic characterizations of electron impact cross sections for important atmospheric gases (namely, O2, N2, O, CO, CO2, and He) are updated. With these cross sections it is simple to communicate massive quantities of experimental and theoretical results. In addition, these forms are convenient for applications in energy degradation calculations, including a new approach described in a companion paper.

Electron impact on atmospheric gases, I. Updated cross sections

Optical excitation function measurements for electron-atom and electron-ion collisions are reviewed. Sources of experimental error are discussed and, for cases in which adequate documentation is provided, publications are reviewed for accuracy of experimental method. The effects of polarization of the emitted radiation and methods of normalization are considered. The reliability of specific reported data is discussed based on these considerations, on the results of consistency checks, and, where possible, on comparison with other measurements. Data sources for 50 atoms and 20 atomic ions are identified. Comparative plots are presented for cases in which enough data are available: H, $\mathrm{He}(n^{1}S, n^{1}P, n^{1}D, 4^{3}S, 3^{3}P)$, ${\mathrm{He}}^{+}$, Ne, ${\mathrm{Ne}}^{+}$, Ar, ${\mathrm{Ar}}^{+}$, Xe, Li, Na, K, Mg, ${\mathrm{Mg}}^{+}$, Ca, Sr, ${\mathrm{Sr}}^{+}$, Cu, ${\mathrm{Zn}}^{+}$, Cd, Hg, and Mn.

Measurements of electron impact optical excitation functions

Revised cross-section values for the excitation of three O I resonance transitions at 1304, 1027, and 989 A, by electron impact on atomic oxygen are presented from threshold to 300 eV. These results are smaller than the excitation cross sections used in some airglow models by a factor of about 2.8. The revised values are in good agreement with recent quantum-scattering calculations. The downward revision is required by new laboratory studies in which the direct and dissociative cross sections for 1304 A excitation were normalized with small probable error to the O and O2 ionization cross sections. The results also reflect new advances in VUV optical calibration techniques. A number of outstanding airglow problems are simplified by these revisions.

Electron impact excitation of atomic oxygen: Revised cross sections

The conditions of electron-impact excitation in flowing oxygen downstream from a discharge are reinterpreted. It is shown that total oxygen mass flow is not conserved as the discharge is turned on and off, even though the inlet flow rate remains constant. The total amount of gas is diminished when the discharge is turned on, apparently due to collection of atomic oxygen by the system walls. A revised total cross section is reported for the excitation of 1304-A radiation.

Electron‐impact excitation of the 3S0 and 5S0 states of atomic oxygen

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

E. C. Zipf

Author Tools

Chat about Author

Papers

Electron‐impact excitation of the 3S0 and 5S0 states of atomic oxygen