A CHEMICAL-DYNAMICAL MODEL OF WAVE-DRIVEN SODIUM FLUCTUATIONS

A comprehensive chemical-dynamical model is used to investigate the interaction of gravity waves with twenty minor species involved in the atomic sodium chemistry in the mesopause region. We find that chemistry becomes important on the underside of the sodium layer, primarily below 85 km altitude, where the relative importance of chemistry in wave-driven sodium fluctuations increases with increasing wave period and increasing horizontal wavelength. We also find that for altitudes below 80 km an adequate determination of the effects of chemistry in these fluctuations requires the inclusion of several reactions related to ozone chemistry. However, the atomic Na density is too low this region to be routinely observed by current sodium lidars. Importantly, we find that above 85 km altitude sodium can be treated as a passive tracer of gravity wave motions.