OZONE AS A TRACER OF TURBULENCE INDUCED BY BREAKING GRAVITY-WAVES ON MARS

A link is established between the vertical structure of the eddy diffusion coefficient and the shape of the ozone profile in the middle atmosphere of Mars. By using a 2-D model of the effect of internal gravity waves on the general circulation pattern (Theodore et al., Icarus 105, 512, 1993a), the eddy diffusion coefficient K is calculated as a function of altitude in solstitial conditions for various latitudes covering polar, mid-latitude and equatorial regions. The vertical profile of K is mainly characterized by a steep increase with altitude above a typical level of almost-equal-to 40 km, in the region of the atmosphere where breaking waves are expected to release their energy. By using a 1-D steady state photochemical model (Blamont and Chassefiere, Icarus 104, 324, 1993), which is proven to provide a realistic diurnal profile of ozone, it is shown that the enhanced vertical transport in the breaking region results in the formation of a thin ozone layer whose contrast is well correlated with the altitude of the breaking level. This correlation is quantitatively analyzed and discussed in view of future observations of ozone by solar and stellar occultation from the Mars 94 spacecraft (SPICAM experiment).