Theoretical and experimental studies of the atmospheric sodium layer

Atmospheric atomic sodium was observed over Urbana using a laser radar system tuned to 589 nm. Wavelike structures in the sodium layer was observed with typical wavelengths of 3-15 km and downward phase velocities of 1-3 m s superscript-1. On one occasion there was evidence for the presence of a standing wave in the layer. During two successive evenings the bottomside of the layer was observed to undulate with a period of about 2 1/2 hours. In agreement with worldwide measurements the layer was observed to broaden through the night. A meteor ablation-cluster ion theory of sodium was developed and found to be in good agreement with existing atmospheric observations as well as laboratory measurements of rate constants. Sodium is removed from the mesosphere in the form of higher order cluster ions which eventually undergo sedimentation to the lower atmosphere.