Experimental evidence for photochemical control of the atmospheric sodium layer

On May 31, 1992, a rocket payload equipped with 10 airglow photometers was launched from the Alcântara Launch Center in northern Brazil. The payload measured sodium, hydroxyl, atomic, and molecular oxygen airglow emissions, and a sodium lidar, operating at the launch site, provided simultaneous vertical profiles of atmospheric sodium density. The airglow profiles, in conjunction with the sodium density distribution, are used to derive vertical profiles for atomic oxygen, ozone and hydrogen in the 80 to 100 km region. These profiles are then used as inputs to a photochemical model for the sodium layer. Good agreement is achieved between the modeled and experimental profiles of sodium and Na D line airglow, and the results indicate that the branching ratio for the production of Na( 2 P) in the reaction NaO + O → Na( 2 P, 2 S) + O 2 must be between 0.05 and 0.20.