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Abstract

The influence of a monochromatic atmospheric gravity wave of fixed
amplitude on the mean vertical distribution of mesospheric minor species
is studied using a dynamical-photochemical gravity wave model. The
fluctuations of winds, temperature, and species concentrations produced
by the wave are calculated by a coupled linear gravity wave model. The
effects of the wave on the mean mixing ratio of 19 key chemically active
species is derived from a coupled system of continuity equations which
accounts for full nonlinear photochemistry in a vertical column. This
study focuses on the impact that gravity wave induced nonlinearities in
the chemical reaction rates has on the chemical species distribution.
The effects of gravity wave induced chemical transport and background
diffusion are also calculated. Calculations indicate that the impacts of
gravity waves on the vertical distribution (mean concentration) of
atmospheric minor constituents are largest in the mesopause region,
especially during nighttime. A comparison of the three effects indicates
that for short lifetime chemical species such as O-3 and OH, the
tendency due to chemical reaction perturbations induced by gravity waves
is much greater than that due to transport and diffusion. The altitude
range over which these nonlinearities is important is narrowly confined
to the chemically active region near the mesopause.