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Recent observations of the OI 8446 A emission over Millstone HillEvening twilight spectra of the OI 8446 A emission were obtained during May and June of 1993 using a single-etalon, pressure scanning, Fabry-Perot interferometer located in the Millstone Hill Optical Facility. The goals of this work are to positively identify the 8446 A emission in the twilight airglow and to determine the intensity decay as a function of solar depression angle. Also, a study of the relative triplet line strengths is performed in hopes of establishing the importance of the primary excitation mechanisms (photoelectron impact or Bowen fluorescence) during the twilight period. Although absent in most of the data, a distinct auroral influence is also found to contribute considerably, on occasion, to the emission over Millstone Hill. The ratio of the combined 8446.26 A and 8446.38 A intensities to the 8446.76 A intensity varies as 0.13 +/- 0.03 per degree of solar depression angle, indicating that secondary excitation mechanisms are becoming increasingly important as evening twilight progresses. Bowen fluorescence is not found to be the primary excitation mechanism at any time during twilight, contributing just a few Rayleighs at most. These observations are an important first step toward a better characterization of highly variable thermospheric oxygen concentrations through ground-based measurements of the OI 8446 A emission.
Document ID
19950035282
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lancaster, R. S.
(Boston University Boston, MA, United States)
Kerr, R. B.
(Boston University Boston, MA, United States)
Ng, K.
(Boston University Boston, MA, United States)
Noto, J.
(Boston University Boston, MA, United States)
Franco, M.
(Boston University Boston, MA, United States)
Solomon, Stanley C.
(University of Colorado, Boulder, CO United States)
Date Acquired
August 16, 2013
Publication Date
May 1, 1994
Publication Information
Publication: Geophysical Research Letters
Volume: 21
Issue: 9
ISSN: 0094-8276
Subject Category
Geophysics
Report/Patent Number
ISSN: 0094-8276
Accession Number
95A66881
Funding Number(s)
CONTRACT_GRANT: NSF ATM-91-57121
CONTRACT_GRANT: NAGW-2116
CONTRACT_GRANT: NSF ATM-91-02314
Distribution Limits
Public
Copyright
Other

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