COMPREHENSIVE MODEL FOR THE ATMOSPHERIC SODIUM LAYER

We present a steady state model of the midlatitude nighttime sodium la yer which is comprehensive in the sense that it includes deposition of the metal, diffusion, and kinetics as well as the seasonal variations in the atmosphere. The model is used to compute seasonal variations i n the layer parameters and the sodium nightglow. The behavior of the m odel reproduces well the observed behavior of the layer. We find that the main contributor to the seasonal variation is the temperature depe ndence of the reaction recycling atomic sodium from NaHCO3. Seasonal v ariations in the atmospheric minor species including ozone are seconda ry effects at best. The relative contributions of all factors are comp ared.