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Detailed Reference Information |
Slanger, T.G., Cosby, P.C. and Huestis, D.L. (2003). Ground-based observation of high-altitude, high-temperature emission in the O2 atmospheric band nightglow. Journal of Geophysical Research 108: doi: 10.1029/2003JA009885. issn: 0148-0227. |
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O2(b1Σg+ - X3Σg-) atmospheric band emission, when viewed from the ground outside the auroral zone, is considered to originate in the 90--100 km altitude region, from O-atom recombination. However, the v = 0,1 levels of the b1Σg+ state can also be generated through an energy transfer process, when O(1D) collides with O2. In the absence of specific altitude information, as in ground-based measurements, the two sources can still be distinguished because of different characteristic temperatures. We have analyzed sky spectra from the Keck I and II telescopes on Mauna Kea, contrasting solar minimum and maximum conditions and variations with time of night. Utilizing the O2(b-X) 1-1 band, we find that in averaged solar minimum conditions, ~75% of the emission comes from an altitude corresponding to 200 K, while ~25% has a temperature near 700 K and therefore originates at high altitude. The fraction of high-temperature emission is often considerably greater early in the evening. At solar maximum, the high altitude component can be dramatically enhanced in the early evening; emission in the 1-1 band reaches intensitities of 100--150 R, with a rotational temperature near 1000 K. We also observe high-J b-X 0-0 band lines penetrating the Fraunhofer A-band region, the normal absorption becoming emission. Emission intensites deduced from such observations indicate that the ionospheric 0-0 band is at least as intense as the 1-1 band, as expected. |
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Abstract |
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Keywords
Atmospheric Composition and Structure, Airglow and aurora, Ionosphere, Equatorial ionosphere, Ionosphere, Ion chemistry and composition, Atmospheric Composition and Structure, Chemical kinetic and photochemical properties, Atmospheric Composition and Structure, Ion chemistry of the atmosphere (2419, 2427) |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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