CONCURRENT OBSERVATIONS OF AURORAL ACTIVITY AND A LARGE SPORADIC SODIUM LAYER EVENT DURING ANLC-93

Prominent sporadic sodium (Na-s) layers, apparently associated with intense auroral activity, were observed during the 1993 Arctic Noctilucent Cloud Campaign (ANLC-93) with an airborne sodium lidar on the August 6 flight near 51 degrees N latitude. The peak density of the Na-s layer reached 74,500 cm(-3). The zonal extent of the Na-s layers exceeded 1600 km. Strong auroral emissions were recorded with an all-sky imager on the aircraft. A Michelson Interferometer was used to measure the intensity of OH nightglow between 85-90 km. OH rotational temperature exhibited no obvious correlation with the Na-s layer peak density near 94 km. The data Suggest a connection between the Na-s layers and auroral electron precipitations. The data also support the conjecture that dust and smoke particles may play a crucial role in the Na-s layer formation.