OBSERVATIONS OF TWILIGHT AND SUNLIT AURORA
- 1 October 1962
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Physics
- Vol. 40 (10), 1370-1384
- https://doi.org/10.1139/p62-144
Abstract
The 3914-Å band of [Formula: see text] has been observed in the zenith at twilight by a photoelectric spectrometer; simultaneous measurements of the 5577-Å line were made as a check on auroral activity. A small twilight enhancement was probably observed in the absence of aurora in 1960, but it could not be detected in 1961. After subtraction of this background, the auroral measurements showed [Formula: see text] densities of about 1000 ions/cm3 at 160 km, with a sharp decrease at lower altitudes; some displays, presumably located near 100 km, showed no twilight effect at all. It is suggested that [Formula: see text] ions are rapidly removed in the 100-km region by either charge–exchange or ion–atom interchange reactions which convert them into NO+ or some other ion. The ions in the twilight airglow are therefore probably located at 550 to 620 km, being produced there by solar extreme ultraviolet. However, this process requires a much higher N2 concentration at such heights than is normally supposed. This may be produced at times of high solar activity, and especially during magnetic storms.Keywords
This publication has 9 references indexed in Scilit:
- Electron-Ion Recombination Coefficients in Nitrogen and in OxygenPhysical Review Letters, 1961
- Preliminary data on solar extreme ultraviolet radiation in the upper atmosphereJournal of Geophysical Research, 1961
- A comparative study of absolute zenith intensities of [O I] 5577Journal of Geophysical Research, 1960
- Measurements of the mean lifetime of the metastable 1S-state of the oxygen atom in the upper atmosphere during auroral displaysJournal of Atmospheric and Terrestrial Physics, 1955
- The auroral E-layer ionization and the auroral luminosityJournal of Atmospheric and Terrestrial Physics, 1955
- The effect of rayleigh scattering and ground reflection upon the determination of the height of the night airglowJournal of Atmospheric and Terrestrial Physics, 1954
- The emission of the negative system of nitrogen from the upper atmosphere and the significance of the twilight flash in the theory of the ionosphereProceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1949
- The Light of the Night SkyReviews of Modern Physics, 1942
- Spectrographic Studies of the Planets. George Darwin Lecture, delivered by Dr. V. M. Slipher, Assoc.R.A.S., on 1933 May 12Monthly Notices of the Royal Astronomical Society, 1933