MAINTENANCE OF TROPICAL NIGHT-TIME F LAYER

OBSERVATIONS of the oxygen red lines in the night airglow have been in progress at the Haleakala Observatory of the Institute for Astronomy, University of Hawaii, since 1961. It is generally acknowledged that most of this emission arises from the dissociative recombination of O+2 in the F layer of the ionosphere1. Recently we have been using simultaneous observations of the ionospheric electron content made with the Faraday rotation technique to determine the proportionality constant connecting the electron loss and quantum emission rates. In a previous paper2 we estimated that about fifteen photons in the 6300/6364 forbidden doublet of atomic oxygen are produced for every 100 electrons that recombine in the night-time ionosphere. Later observations, made in the winter of 1966, show that this efficiency can vary by as much as a factor of 2 above and below this value. © 1968 Nature Publishing Group.