Concurrent observations of auroral activity and a large sporadic sodium layer event during ANLC‐93

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Abstract
Prominent sporadic sodium (Nas) 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°N latitude. The peak density of the Nas layer reached 74,500 cm−3. The zonal extent of the Nas 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 Nas layer peak density near 94 km. The data suggest a connection between the Nas layers and auroral electron precipitations. The data also support the conjecture that dust and smoke particles may play a crucial role in the Nas layer formation.