Rocket measurements of the sodium dayglow

Abstract

Sodium dayglow photometers were flown on Aerobee rockets on the mornings of April 7 and June 19, 1964. Good profiles of the emission were obtained for comparison with twilight measurements. In June, the twilight and daytime abundances were the same; the vertical distributions agreed fairly well. In April, the daytime abundance was greater by a factor of about 1.45; the heights were again nearly the same. The top of the day layer had the remarkably small scale height of 3 km. Photochemical theory, including the recent version by Blamont and Donahue, predicts a topside scale height of 7 or 8 km and a considerable lowering of the daytime layer. It is suggested that a new factor must be introduced, consisting of an equilibrium between sodium atoms and a distribution of dust particles. Under some conditions, atoms may evaporate from these particles in the daytime and return to them at night. Another photometer on the June flight was unable to detect any lithium emission. The upper limit thus set to the lithium abundance is consistent with the low part of the range observed in twilight.