A CHEMICAL-DYNAMICAL MODEL OF WAVE-DRIVEN SODIUM FLUCTUATIONS

A comprehensive chemical-dynamical model is used to investigate the in teraction of gravity waves with twenty minor species involved in the a tomic sodium chemistry in the mesopause region. We find that chemistry becomes important on the underside of the sodium layer, primarily bel ow 85 km altitude, where the relative importance of chemistry in wave- driven sodium fluctuations increases with increasing wave period and i ncreasing 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 oz one chemistry. However, the atomic Na density is too low this region t o be routinely observed by current sodium lidars. Importantly, we find that above 85 km altitude sodium can be treated as a passive tracer o f gravity wave motions.