Formation characteristics of sporadic Na layers observed simultaneously by lidar and airglow instruments during ALOHA‐90

Sporadic Na (Na_s) layers were observed by the airborne lidar during ALOHA‐90 on the 22, 25 and 27 March flight missions. Perturbations in the O₂ and OH nighttime airglow emission intensities and temperatures were also observed by instruments on the aircraft and at Haleakala Crater (20.8°N, 156.2°W) during these events. The most striking correlation between the airglow and lidar measurements occurred during the northbound flight leg of the 25 March mission. When the Na_s layer formed at 90.7 km, while the Electra aircraft was between 750 and 500 km south of Haleakala, the O₂ temperatures near 95 km above the Electra and Haleakala increased by approximately 45 K. The data for this night suggest a connection between Na_s and a large‐scale wave, and suggest that the wave is tidal in nature. The data also suggest that some Na_s layers can form very quickly over large geographic areas. Fast chemical processes are required to generate the large amounts of atomic Na involved in some of these events.