Proceedings with Extended Abstracts (single PDF file) - Radio ...

The main recently assumed mechanism of penetration of stratospheric ozone into thetroposphere is its transport by the general atmospheric circulation from equatorial latitudesand descending of the air in the middle latitudes [Holton, 1990]. The mean downward ozoneflux due to the circulation transport is estimated to be about F ~ 7×10 14 м -2 s -1 [Ebel et al.,1993], while the estimations of tropospheric ozone require the fluxes of stratospheric ozone ofthe order of (4-8)×10 14 м -2 s -1 [e.g. Crutzen, 1988]. Comparison of these values with theestimations of the ozone diffusion flux obtained above show the comparability of thesevalues. Therefore, the turbulence generation by gravity waves near the tropopause mayproduce substantial transport of ozone from the stratosphere to the troposphere.One can estimate the time scale characteristic for the transport into the troposphere of allstratospheric ozone (in the absence of its sources): τ ~ N/F, where N is the total ozone contentin the atmospheric column above considered altitude. Described above estimations of Ktogether with the model of vertical ozone distribution [Zuev and Komarov, 1986] lead to thevalues of τ ~ 0,3 – 3 day -1 . These values show that the changes of IGW intensity andturbulence near the tropopause may relatively fast lead to the changes of stratospheric ozoneconcentration and to a shift in the photochemical equilibrium. Therefore, local enhancementsof IGW intensity and turbulence at tropospheric altitudes over mountains due to theirorographic excitation may lead to the changes in total ozone over mountain regions. This mayexplain observed TO anomalies over mountain regions [Kazimirovsky and Matafonov, 1998].3. ConclusionA numerical simulation was used to verify the hypothesis about the influence of sharpchange of vertical temperature gradient at the tropopause on the increase of the amplitudes ofIGWs propagating upwards from the troposphere. Estimations of vertical ozone flux from thestratosphere to the troposphere are comparable with usually supposed ozone downwardtransport with the general atmospheric circulation.Acknowlegement. This study was partly supported by the Russian Basic ResearchFoundation and by the International Science and Technology Center.References.Crutzen, P. J., Tropospheric ozone: An overview, In I.S.A Isaken (ed.), TroposphericOzone, D. Reidel Publ. Company, Dordrecht, 3-32, 1988.Ebel, A., H. Elbern, and A. Oberreuter, Stratosphere-troposphere air mass exchange andcross-tropopause fluxes of ozone. In Coupling processes in the lower and middle atmosphere,eds. Thrane, ER. V. et al., Kluner, Dortrecht, pp. 49-65, 1993.Fukao, S., M. D. Yamanaka, N. Ao, W. K. Hocking, T. Sato, M. Yamamoto, T. Nakamura,T. Tsuda, and S. Kato, Seasonal variability of vertical eddy diffusivity in the middleatmosphere, 1. Tree-year observations by the middle and upper atmosphere radar, J. Geophys.Res., 99, 18,973-18,987, 1994.Gavrilov N. M., Parameterization of momentum and energy depositions from gravitywaves generated by tropospheric hydrodynamic sources. Ann. Geophys.,15, 1570-1580, 1997.Gavrilov N. M., Yudin V.A. Model for Coefficients of Turbulence and Effective PrandtlNumber Produced by Breaking Gravity Waves in the upper Atmosphere, J. Geophys. Res.,97, 7619 -7624, 1992.Holton, J. R., On the global exchange of mass between the stratoshere and troposphere, J.Atmos. Sci., 47, 392–395, 1990.Kazimirovsky, E. S., and G. K. Matafonov, Continental scale and orographic structures inthe global distribution of the total ozone, J. Atmos. Solar-Terr. Phys., 60, 993-996, 1998.Zuev, V. E., and V. S. Komarov, Statistical models of temperature and gas components ofthe atmosphere, Hydrometeoizdat Press, Leningrad, 1986.237