Observations of the Lithium Lines in the Twilight Airglow in the Northern Hemisphere

Abstract

THE recently published discovery of the lithium resonance line in the twilight airglow by Delannoy and Weill¹ and further observations of the emission by Gadsden and Salmon² have led to a discussion as to the origin of the lithium atoms in the upper atmosphere. Barbier, Delannoy and Weill³ have considered the possibility of marine and meteoric origins for the lithium and have favoured the latter hypothesis because the derived abundance ratio lithium/sodium agreed better with the ratio for the meteoric material. Donahue⁴ has suggested that the lack of linearity in the relation between sodium brightness and abundance could make ambiguous any conclusions based on the lithium/sodium brightness ratio alone. A third possibility suggested by the U.S.A. International Geophysical Year Committee⁵, and supported further by Barber⁶, is that the lithium originates from ‘hydrogen’ bomb tests at high altitude ; it is suggested, in particular, that the high-altitude Johnston Island test of August 1, 1958, was responsible for the lithium emissions reported by Gadsden and Salmon from Antarctica and New Zealand. In view of the uncertainty of present knowledge of the behaviour of the lithium emission, an observation from a station in the northern hemisphere should be of interest.